Vol_24_CoffeeAgron by jizhen1947


									 Review of Kenyan
Agricultural Research

       Vol. 24
 Coffee Agronomy

     A M Mailu
Preface v
Acknowledgements              vii
Notes   viii
Agronomy    9

         Introduction                           9
         Coffee management                      9
         Nutrition                             11
         Intercropping                         21
         Seeds and seedlings development       24

Processing and Quality   25
         Pulping                               25
         Grading                               25
         Fermentation                          25
         Drying                                26
         Storage                               27
         Quality                               27
         Effluents                             28

Economics of Coffee Production 29
         Estates sector                        29
         Smallholder sector                    29
         Marketing policies                    30

   These reviews have been produced as part of the Kenya Agricultural Research
Database Project which was funded by the Netherlands government over the years 1992
to 1996. The aim of the project was to document all investigations and research related
to agriculture in Kenya undertaken since the end of the last century, especially those
items which had not been published. The computerised database now contains around
40,000 records, most of which contain abstracts or summaries, full bibliographic details,
and information about where the documents can be found. We are conscious however,
that many items have not yet been included, especially the earlier material and many
consultancy reports produced by foreign and international donor, development, and
research organisations. Specialists who read the reviews may be aware of important
topics which have been omitted by the reviewer. If this is the case, we would ask that
both the reviewer and KARI‟s Library and Information Services be informed so that the
topic can be included in future revisions. Constant up-date will be required as new
research information becomes available with the National Agricultural Research System
in Kenya.
   The central database (KARD) is available in the Library and Information Services
unit at the Headquarters of the Kenya Agricultural Research Institute. Copies are also
held on computers in the libraries at the KARI research centres in Muguga, Embu,
Katumani, Mtwapa, Kitale, Njoro and Homa Bay. There are also extra copies available
at the National Agricultural Research Laboratories and the Agricultural Information
Centre. It is hoped that use will be made of this database by both public and private
   Although the Centre for Arid Zone Studies at the University of Wales in Bangor has
acted as the technical “backstopping” organisation, the project has relied primarily on
the work of Kenyan scientists who wrote the abstracts, edited them and managed the
database. The opinions included are those of the authors and do not necessarily reflect
the views of the editors, KARI or CAZS. The project has used the database as the
primary source for the production of this series of research reviews which, we hope,
will provide insight into the past research and hopefully point out areas where future
work should be focused, not only to the advancement of agricultural research in Kenya
and the region, but perhaps more importantly, through promoting cost-effective
research, to the national economy and the well-being and productivity of the nations‟

                                                                             CG Nderitu
                                                                         Director, KARI

                                                                           January 1996

                  Explanatory note on the establishment of KARI

Although KARI was established in 1979 through an amendment to The Science and
Technology Act (Cap 250), it was not until 1989 that all relevant National Research
Stations had been consolidated under one management. The description of KARI
on the back cover of this review should be read in the light of this.

Dr A M Mailu
Deputy Director

   As always, it would be impossible to mention everyone who has contributed to the
success of the project. However I would particularly like to thank the Project Manager
in Kenya, Dr. A.M. Mailu, Deputy Director (Crops) of the Kenya Agricultural Research
Institute who has provided guidance to the project and help in overcoming logistical
problems, especially in looking for staff to compile and manage the database. I would
like personally to thank all those past and present members of the database unit who
have helped with the compilation and management of the database, especially the
information officers: Ms Angela Kabiru, Mr John Lugovane, Ms Mary Gachihi, Mrs
Jane Ireri, Ms Jacinta Kimwaki, Ms Irene Onyancha and Ms Vivien Ndhoha, and the
data entry clerks: Mrs Pauline Mburu, Mrs Hannah Mwauro, Mrs Margaret Wambale,
Mrs Lydia Kibira and (occasionally) Mrs Philomena Kaudo and Mr Peterson Ndirangu.
I should also like to thank all the scientists who wrote abstracts for the database, the
editors who corrected them and the scientists who have written reviews in the series.
   I am also grateful to Dr AG Chamberlain for his many contributions to the project
organisation and especially the development of guidelines for writing and editing of
both the abstracts and the reviews; to Mr RA Tyler for technical and editorial assistance
up to the end of 1996; to T Looms for desk top publishing of reviews published after
January 1997; to Dr EM Young for doing much of the final editing work for the
reviews, and to our finance team who have kept the project accounts. Dr WI Robinson,
the Director of the Centre for Arid Zone Studies, should also be mentioned for his
guidance and strategic involvement in the project.
   Finally, both the Centre for Arid Zone Studies and the Kenya Agricultural Research
Institute would like to express their great appreciation to the government of the
Netherlands for funding this project and also to the staff of the aid section of the Royal
Netherlands Embassy in Nairobi for encouragement, patience with our reporting and
requests for extensions, and for their logistical support.

                                                                              Paul Smith
                                                                 Project Liaison Officer
                                                            Centre for Arid Zone Studies
                                                                     University of Wales
                                                                             Bangor, UK

                                                                           February 1997

   Documents quoted from the KARD database have been referred to by their internal 5
or 6 digit acquisition number. The full citation for these references can be obtained by
contacting one of the KARI sites with the database. Other references, not contained
within the KARD database when the reviews were commissioned have been cited in the
footnotes of the main text of the review.
   As of February 1996, KARI sites where the KARD database can be accessed are as

KARI headquarters, P.O. Box 57811, Nairobi, Kenya
National Agricultural Research Laboratories, P.O. Box 57811, Nairobi, Kenya
Regional Research Centre, Embu, P.O. Box 27, Embu, Kenya
National Agricultural Research Centre, Muguga, P.O. Box 30148, Nairobi, Kenya
Regional Research Centre, Mtwapa, P.O. Box 16, Kikambala, Kenya
National Agricultural Research Centre, Kitale, P.O. Box 450, Kitale, Kenya
National Plant Breeding Research Centre, P.O. Njoro, Njoro, Kenya
National Dryland Farming Research Centre, P.O. Box 340, Katumani, Kenya
Kenya National Fibre Research Centre, Kibos, P.O.Box 1490, Kisumu, Kenya

Alternatively, the KARD database can also be consulted via :

Centre for Arid Zone Studies, University of Wales, Bangor, Gwynedd, LL57 2UW
Tel: (+44) 1248 382346
Fax: (+44) 1248 364717
E-mail: Cazs@Bangor.ac.uk


Introduction                                   time (329, 229172, 02907, 20009, 20011).
                                               In the early 1960s, trials indicated that
    The history of coffee and the story of     close spacing, which doubled the plant
how the coffee plant was taken from            density west of the Rift Valley increased
Ethiopia and Kenya via Yemen to the            the production of grade „A‟ beans
countries of Europe and America has been       (02874). The optimum density, which was
documented (236960), as has the                about 5000 trees per hectare for the
introduction of the plant to other countries   compact and disease resistant Arabica
(236964, 31920, 9751, 237427, 32720).          coffee [Coffea arabica var. cauvery
    This review focuses on one of the          (Catimor)] was higher than that required
plantation crops that was under                for all tall types (9169). Further trials
government-controlled cultivation until        planted this area showed that close
the 1950s when its production was              spacing between rows resulted in higher
liberalised in Kenya (02244, 22052). It        yields than the wider row spacings, while
includes a number of specific areas,           within row spacings did not bear a
including coffee plant management and          consistent relationship with yields. Closer
nutrition, and covers the plant from           spacing produced larger beans than wide
seedling to maturity, intercropping,           and normal spacing (02884, 02907,
irrigation, variety trials, processing,        21101, 21870, 22086, 229733, 233700,
quality and the economics of growing           06439, 06746, 14496, 236460, 236466,
coffee.                                        236489, 236498, 32713, 416, 663, 19499).
    Kenya grows mainly mild Arabica                Physiological     and    micro-climatic
coffee, Coffea arabica (L.) mostly at          changes that take place in high density
altitudes of between 1200 m and 2100 m         situations have been studied (235227,
above sea level which receive high rainfall    235223, 236148, 236273). Coffee grown
(above 900 mm) and have fertile arable         at 5000 plants/ha was found to maintain
soils. Thus most research referred to in       better internal water status, moderate leaf
this review, concerns arabica coffee.          temperature       and     high     stomatal
                                               conductance (237260, 237441, 244987,
Coffee management                                  On average, conventional spacing (9 x
                                               9 feet) gave the lowest yield (1827 kg/ha)
Planting and spacing                           of clean coffee. Medium spacing (8 x 8
   The „conventional‟ spacing of 9 x 9         feet) increased yield by 9.2 percent and
feet was adopted from India (14208), but       the proportion of grade „A‟ beans also
earlier experience had shown that coffee       increased from 63.7 percent to 65.7
planted at 6 ft x 6 ft, to 8 ft x 8 ft was     percent. The closest spacing of 7 x 7 feet
found to do well at high altitudes.            increased yield increase by 22.1 percent,
However, trials to find the optimum            but the proportion of grade „A‟ beans
spacing for coffee went on for quite some      decreased to 61.7 percent. The various
                                      Agronomy                                         2

inter-row spacings did not significantly      Spacing under irrigation
influence the size of beans (02907).              In an irrigation trial, it was shown that
However, in Ruiru, wide and medium            monthly irrigation was more effective
spacings produced larger beans, and these     than weekly trickle irrigation and
observations contradicted those made at       necessitated no changes in fertiliser
Koru, where closer spacing produced           timing. Four trees per hole generally
large beans (03039, 04144). Other trials at   produced a greater yield (2472 kg/ha)
Koru showed that there were no                compared to a single tree per hole which
significant differences attributable to       produced about half (1367 kg/ha) (06364).
spacing (06369, 05491). Bench terrace         Thus high density planting may result in
widths were also compared and it was          much better yields, compared to
noted that coffee on broad terraces gave      conventional planting. It was, however,
higher yields than that planted on medium     noted that in many instances high yields
and narrow terraces and that plant            could be obtained from high density
populations higher than normal would          planting only where irrigation facilities
give higher yields only under conditions      were available (06364). High density
of adequate rainfall (06369, 06784). The      planting was noted to maintain better
variety „Caturra‟ performed poorly in         humidity, thus provide better micro-
comparison to „SL 28‟ at high planting        climate than conventional planting, but
densities (06121). However, „Caturra‟         other factors of coffee management would
seemed to do well in the Central Province     need to be borne in mind (06410, 12380).
(06780).                                      These may include interactions between
   Results of 12 years of experimentation     plant densities and fertiliser levels.
in Ruiru and eight years at Koru to find      However, interactions between plant
the optimum hedge spacing for coffee          density, fertiliser levels and irrigation
grown under high-level management             were not significant in some cases
showed that the difference between yields     (06412). Experiments on water use of
in both places was attributable to the        coffee suggested that planting coffee at
methods of pruning employed (14498).          higher densities encouraged deep rooting,
Furthermore, increasing the number of         thus reducing soil compaction, benefiting
trees per hole did not seem to affect the     to both root and general plant growth
long-term clean coffee yields (06446). In     (15366). Although results showed
other trials at Koru, yield increased with    significant differences among varieties for
increasing population at wider spacings       all growth and yield characters, there were
and bean size increased with closer           no significant interactions between
spacing. At Ruiru, however, the widest        genotype and spacing for all characters
spacing produced the highest proportion       except for the numbers of primaries
of grade „A‟ beans (15469, 798, 16254),       (16290, 811, 16429). Additionally, other
while generally the closest spacing           results have shown the effect of spacing
doubled the yield per unit area of land,      on all varieties in the first cycle was
especially during the first crop season       highly correlated (r=0.99), with that of the
(20107, 20510, 20112). It was also noted      second cycle. Total effects, comprising
that optimal densities and pruning cycles     varietal and spacing effects, as well as
depended on altitude, and that some           their interactions for the second cycle
management practices for the older tall       were correlated (r=0.80) with those
types could not be extrapolated to the        obtained in the first cycle (21152). It was,
compact cultivars (201989, 20346).            however, noted that there were other
                                        Agronomy                                       3

factors that influenced yield in close-         Density and sizes of planting holes and
spaced coffee, and two of these had to do       terraces
with amounts of water available in the soil         Various sizes of planting holes (15 x
and the state of the canopies (228244,          15, 30 x 30, 45 x 45 and 60 x 60 cm) and
775). The bearing nodes in both irrigated       density spacing of 2 x 1, 2x1.5 metres at
and un-irrigated coffee showed some             Ruiru and Koru were compared and
differences, with the top canopy bearing        results demonstrated that the disease
nodes per primary increasing linearly with      resistant Arabica cultivar „Catimor‟
the tree density (r=0.87) in the irrigated      required the same size holes and amount
and (r=0.69) in the un-irrigated trees          of manure for establishment as traditional
(800). It was also noted that tree density      varieties (11575). Coffee trees on narrow
and irrigation had a major influence on the     terraces produced the lowest yield
yield components of close spaced coffee.        contradicting earlier results, when it had
Irrigation experiments have continued to        produced the highest yield (14494). In a
give more clean coffee per hectare than         trial on spatial arrangements of the dwarf
un-irrigated coffee (819).                      variety „Caturra‟, „SL 28‟ yielded more
                                                than „Caturra‟ at all levels of planting
Rotation by stumping                            densities. Further, it was noted that an
    In a stumping experiment, a density of      increase in the number of seedlings
5000 plants/ha gave maximum yields at           planted per hole progressively decreased
all sites in the first cycle after stumping     the yields. Generally, one and two plants
(15322). Other density x stumping cycle         per hole gave higher yields (02836,
trials further indicated „SL 28‟                20493, 20036, 20049).
outperformed „Caturra‟ at all sites and             In other trials undertaken to compare
production was highest at the density of        the effects of broad, medium and narrow
5000 trees/ha, but at other sites production    terraces, it was shown that whatever the
was highest at higher trees densities (797,     terrace widths, yields increased with
15324). It was further indicated that a new     closer spacing and narrow terraces
cycle should be carried out in high density     produced lowest yield of coffee at all
coffee after the third crop, since after this   spacings (14494, 22087, 15038). In Meru,
harvest, spacing would have significant         it was noted that closed spacings, (48
effects on growth, height and radius of the     square feet per tree) on a broad bench was
trees (15326). On stumping cycles, three        superior to other combinations of spacing
and six years gave the highest yields, and      and bench widths (15047, 667, 05346).
there was no significant interaction effects    Over a fifteen year period it appeared that
between plant density, cultivar or length       increases in tree density up to twice the
of stumping cycle (17254, 02721, 01630).        normal density progressively increased
However, the six year pruning cycle gave        clean coffee yield (17259, 18451). Earlier
higher yields than the 3 year cycle             experiments in the 1950s on crop yield
(18461), and the two highest plant              and number of trees in the planting hole
densities (5000 trees/ha and 7468 trees/ha)     had indicated that yield/ha increased with
recorded maximum yields in Tinganga,            trees/hole or stems/ha and each stem was
Jacaranda and Makuyu and generally „SL          endowed with an individual root system
28‟ performed better than „Caturra‟             (20498). There was a significant spacing
(19715).                                        effect on bean size, which was better at
                                                medium density and liquor quality (better
                                                at highest density), with „Caturra‟
                                      Agronomy                                        4

showing poor results for both characters      in the 7th year free growth produced the
(22108).                                      highest clean coffee yields, followed by
   For good coffee establishment, the         conventional      multiple    stem,    then
optimal planting hole size was noted not      rotational stumping. Side pruning gave the
to exceed 45x45 cm and manure used            lowest yields (02853, 06009, 15471,
should not exceed 50 percent of a mixture     13671). On coffee grown as a single-row
with top soil for 1-2 trees per hole          hedge, conventional multiple stems with
(32412). The largest hole size (60x60 cm)     heads at 1.37 m gave the highest yield
was however superior in Kirinyaga and         (02993, 06501). Secondary pruning had
smaller holes (30x30 cm) were ideal in all    no significant effects on yield, but
well prepared fertile soils (32673).          generally had highly significant effects on
                                              bean size. After ten years, pruning to
Pruning                                       leave longer heads significantly increased
   Different systems of coffee pruning        overall yields of clean coffee (03042). In
and their advantages and disadvantages        Kisii, long-term yield results indicated
have been investigated for both               that hedgerow spaced coffee should never
smallholder and state sector producers        be capped if high yields are to be expected
since the 1940s (237117, 237317, 32454,       (04169). Although capping delayed the
536, 666, 675, 813, 810, 545).                first crop, this was overcome in
                                              subsequent crops, and it was noted that
Pruning systems
                                              yields increased with tree density at all
   Pruning procedures described for
                                              sites (04813, 06108).
coffee include single and multiple stem
                                                  Rotational stumping of coffee, pruning
systems. It was noted that the multiple
                                              and inter-planting of stumps with
stem system allowing for 4 stems gave
                                              seedlings have been studied. It appears
highest yields. Overall, the two forms of
                                              that inter-planting to double the
multiple stem pruning studied were
                                              population could increase clean coffee
significantly superior in terms of crop
                                              yields, and this increase was higher where
yields than the single stem system (17395,
                                              old trees were inter-planted with old
15038, 15257). However, other workers
                                              stumps than with young seedlings.
have indicated that the highest yields were
                                              Further, rotational stumping and two
obtained from trees with a single stem
                                              conventional uncapped multiple stem
capped once or single stems with two
                                              treatments (where lower primary branches
multiple heads. However, the yield
                                              were cut) gave highest yields (15472,
differences were not significant (15036,
                                              22099).      This    contradicted    earlier
15053, 15380). It was further shown that
                                              observations, where inter-planting with
capping seedlings after field establishment
                                              young seedlings had produced higher
delayed production of the first main crop
                                              yields (06208, 06740, 15471, 16256).
(9182). Generally, yields decreased with
                                              Pruning immediately the crop had been
increasing numbers of stems/tree and one
                                              stripped resulted in higher yields than
stem/tree was recommended for high
                                              pruning after the main flowering, but the
density coffee (17787, 15468). Pruning
                                              yield differences were not statistically
treatments (structural stumping on a five
                                              significant (06647, 13445). In contrast, it
year cycle; conventional uncapped
                                              was further noted that for single and
multiple stem; side pruning; free growth
                                              multiple stem pruning systems where
with a head; capped multiple stem pruning
                                              potential for a good crop existed, early
with a free growth with two capped at
                                              pruning would be beneficial and the
1.82m) were compared. It was shown that
                                       Agronomy                                         5

multiple stem system would yield more. It      physiological reason for pruning is to
was also noted that delayed pruning            open up the tree for efficient light
resulted in higher grade „A‟ bean yields,      penetration. The lowest Leaf Area Index
but these differences were not statistically   (LAI) was shown by trees pruned to three
significant (13680, 14200, 15032, 22100,       quarters level. It had been shown
9205).                                         previously that pruning up to the quarter
    Artificial shading reduced the rate of     level (25% of leaves removed) did not
growth of single stem trees. Shade also        adversely affect the physiology of the tree,
resulted in larger and darker leaves           but enhanced dry matter production and
(13749). It was concluded, through other       water relations (19726). It was also shown
trials, that neither cropping level nor        that various pruning, timing and moisture
pruning system alone or in combination         regimes changed the cropping pattern and
have more than minor effects on the            thus the flowering pattern considerably.
general shape of trees‟ annual growth          Generally, December was shown to be the
curves (13937). Generally, although yields     best time for pruning operations in the
in individual years showed some great          Central Province area (19731). It was
differences between treatments, there was      shown that farmers could prune their trees
no significant difference in production        up to 25 percent and that coffee trees
from single and multiple stem pruning          spaced at 2.74 x 2.74 m (or 3 m x 3 m)
systems. In the long run, the differences in   performed better when they were capped.
both the coffee yield and grade „A‟ coffee     Removal of 25 percent of total foliage
declined but there was a trend in favour of    increased carbon dioxide assimilation, in
multiple stems, when grade „A‟ yield was       contrast to 50 percent of the foliage
expressed as a percentage of gross             (237285).
production (14197, 14199). From general           Although differences due to pruning
results and field observations the most        treatments      were     not    statistically
satisfactory treatment was to restrict the     significant, there was some indication that
number of primaries per tree to 25 and to      one and two heads per tree produced
allow 3 ft of wood to bear each year           higher clean coffee yields than four heads
(14198). In other trials, overall, after 4     (02821, 16255). Rotational stumping and
years, delayed cropping gave more than         removal of 2 heads as in conventional
either of the early cropping treatments. It    spacing was not satisfactory, but inter-
was also shown that light pruning was not      planting to double the tree population
beneficial, unless the trees were de-          increased coffee yields up to 60 percent,
cropped in the early years (15032). A          with best results from using seedlings
significant interaction between de-            (02825). Conventional multiple stem
cropping, length of head and method of         pruning gave the highest yields, then
secondary pruning had earlier been             capped multiple stem, while rotational
indicated (16067).                             stumping had the lowest yields (02828).
                                               Further, it was shown that the best method
Pruning levels
                                               of pruning hedgerow spaced coffee was
   Pruning levels supported by carbon
                                               the conventional (uncapped) multiple stem
dioxide     assimilation   measurements
                                               system (17950, 20506).
indicated that leaves removed to secure a
25 percent pruning level were most
appropriate (02732). Pruning times helped
regulate extension growth and thus
flowering, (02743) and the main
                                        Agronomy                                       6

Practice with Ruiru II cultivar                     Yield correlated with leaf fall and
   Replacement of existing cultivars with       attempts to reduce leaf loss through the
„Ruiru II‟ indicated that the highest yields    use of copper sprays produced a larger
were recorded where „Ruiru II‟ was              crop. However, there was a trend for
planted as a hedgerow system with one           decreasing bean size as yield increased
head uncapped. Uprooting old trees and          and it appeared increases induced by the
planting „Ruiru II‟ recorded highest yields     treatments were slightly offset by a small
in a capped French Mission coffee estate        decrease in the weight of beans (17795,
and enhanced production of large beans          9463). Hormonal control of flower bud
(32674). Further, „Ruiru II‟ yields             dormancy was not evident, through the
increased with tree density at all sites, and   use of abscisic acid (ABA) or gibberellic
capping appeared to delay the first crop,       acid (GA, GA3) (03063). However, an
but trees caught up in subsequent crops         increased growth rate was induced by
(32685). However, removal of the primary        ABA and this increase was much higher
at every node alternatively around the          when GA was present (03070). It was
stem reduced coffee yields significantly,       further suspected that cytokinin was
while deflowering and primary removal           needed to stimulate the liberation of free
tended to increase the percentage of grade      gibberellin from a bound form in the buds
„A‟ beans (32711). This new hybrid              for flowers development and dormancy to
variety may be used to replace other            be broken (15813). Some reduction in
traditional varieties by uprooting the          flowering frequency might be achieved by
existing ones (227896).                         using anti-transpirants (16709). It was
                                                observed that generally, plant growth
Change of cycle in hedge-row coffee             regulators were incapable of controlling
    During a change of cycle in coffee,         flowering in a practically useful way,
tallest suckers were obtained from              especially flower bud dormancy, shoot
conventional multiple stem, while the           growth and flower initiation by use of
thickest suckers were obtained after            both gibberellic acid and growth
stumping. Further, three bearing heads per      retardants. Trees flowered less frequently,
tree produced the tallest suckers, while        but more intensely in the closed leaf
two bearing heads per tree produced thick       canopy, at close spacings (21228, 22021,
suckers. It was also noted that three           237426, 354).
bearing heads per tree produced                     The effect of dichlorophenoxyacetic
significantly more branches than two            acid (2-4D)on leaf fall indicated that 2-4D
bearing heads (815). Overall, in Meru, the      slowed down growth extension for 4
highest yields were obtained after              weeks following treatment but it failed to
stumping treatments, followed by the            reduce leaf loss (442).
conventional multiple stem system (816).
                                                Fruit formation and development
Flowering and leaf fall                            The physiology of fruit development
   It was shown that the removal of one         and the use of plant hormones, e.g.
primary every three months resulted in the      cytokinins, and coffee regulators has been
highest yields, while deflowering and           studied and reported. Treatment of fruits
removal of the primary branches tended to       with GA3 or kinetin or their combinations
increase the percentage of grade „A‟ beans      increased fruit volumes and dry weights,
(17937).                                        and fruits ripened ten days earlier than
                                                normal (02888). The relationship between
                                        Agronomy                                       7

time of flowering and the development of        cuttings indicated that the rooting compost
fruit in relation to rainfall and the anatomy   should not be too firmly pressed down;
of the tree has been studied (06637). In        single node cuttings with two full leaves
other experiments GA3, kinetin or               rooted faster and grew better than cuttings
combinations of both increased volumes          with trimmed leaves, and the use of
and the fresh and dry weights of fruits by      yellow-orange coloured plastic material to
50 percent (441). The pinhead stage was         shade the plants had some beneficial
found to be the most appropriate stage for      effect on percentage of rooted cuttings and
GA3 application when volume or fresh            a remarkable positive effect on shoot
fruits and dry weight of beans were             growth (388, 22018, 236352, 236412,
related to the concentration of GA3             237436, 237400). From a grafting
applied (499).                                  programme, some 4000 seedlings were
    Generally, east of Rift Valley there are    produced with 110 genotypes (16277,
two main flowering periods. In the short        32426). Tissue culture technology for
rains flowering occurs mainly from June         micro-propagation of coffee has great
to October and for long rains from August       potential, as has been shown in Malaysia,
to January (34599).                             Singapore and Indonesia (237056).

Vegetative propagation                          Variety trials
    Side grafting of new clones on                  Trials were established in various
seedlings was tried and results indicated       locations to evaluate coffee varieties for
that the method was likely to be                various agronomic traits, including
successful, and give gains in time and          evaluations for yields, quality and
reduction in production costs (06785,           disease/pest resistance. Among the
06035, 06124, 01644, 05157, 32403).             genotypes that were evaluated were clones
Tissue culture also has the potential for       of high yielding and CBD/rust-resistant
the propagation of desired clones and           trees from Ethiopia, Madagascar and
again time and production costs are saved       Sudan (00929, 02852, 16271, 229148,
(21492, 32718, 796, 04808, 19723).              229314, 235093, 236116, 235931,
    A compost consisting of vermiculite,        237279, 237304, 649, 9210, 237403,
coffee hulls and coarse sand gave the best      237471, 238500, 16652, 238525, 17126,
results for rooted coffee cuttings (15150).     31997, 17788, 32213, 330, 331, 33388).
In comparative trials, some of the clones       „Ruiru II‟, a coffee strain developed in
showed a high level of resistance to coffee     Kenya, which is resistant to both coffee
berry disease (CBD) and rust, though the        leaf rust and coffee berry disease and has
disease incidence was not severe (16276).       been evaluated in a number of
Large scale clonal propagation has been         environments and can be planted more
considered in the Arabica coffee hybrid         densely, is capable of yielding 48 kg/tree,
„Ruiru II‟ and various methods of               compared to 16 kg/tree with traditional
vegetative propagation have been applied        strains. It bears one year earlier and
to the hybrid (200572). Propagation by          matures six months earlier than most
cuttings was noted to be an easy and very       established varieties (236978, 237031). It
efficient method, while grafting had the        is reckoned that this hybrid will cut on
advantage that existing coffee trees could      production costs up to 60 percent through
be converted to „Ruiru II‟ without the          savings made through the reduction of
need for re-planting (21504, 22018,             pesticide use (237031). It has been shown
32500). Further results of propagation by       that „Ruiru II‟ is not only high yielding,
                                       Agronomy                                        8

but produces good quality Arabica coffee           Variety trials have been conducted in
(237048). The adoption of this strain was      all coffee growing areas, giving varying
expected to result in additional production    results from place to place. Some varieties
of coffee in Kenya (237159, 237245,            were further selected for their good liquor
243563, 244150, 245399, 795, 807).             and ability to withstand drought but in
   It was observed that generally,             many instances yield differences were not
seasonal fluctuations in rainfall, altitude    significantly different among the various
and soil differences contributed to yield      selections (15382, 15388, 15389, 16646).
difference between years and sites, and        In all cases, copper fungicide sprays
that variations due to genotype/location       increased the overall proportion of grade
interaction was low. Further, all entries      „A‟ beans (16072, 16461). In many cases,
responded     linearly     to    improving     leaf rust resistance was a crucial
environments (240821, 330, 331, 394,           consideration. The variety „K7‟ showed
12619, 12620, 12621, 13915, 13673,             remarkable rust resistance (16502, 16647,
13694). Nationally, coffee variety trials      16651). In more recent variety trials
were conducted in all provinces and            evaluating a number of coffee hybrids it
districts that had shown potential for         was noted that „SL 28‟ had the highest
coffee production. These includes areas of     grade „A‟ coffee yield and quality as
the Central, Rift Valley, Nyanza, Coast        judged by liquoring tests (19442). This
and Eastern Provinces (649, 650, 667,          paper also reports on the disease
785, 9464, 9598, 05150, 05228, 05713,          resistance of several cultivars.
06104, 11886, 12616, 15061, 13667,                 Evaluations on-farm indicated that the
13697, 14210, 14212, 14571, 14574,             attributes of hybrids were comparable to
14647, 15064, 15065, 15067, 15069,             those of the popular commercial cultivars,
15071, 15072, 15160, 15161, 15164,             „SL 28‟ and „K7‟, and that yields were
15166). In general, three „SL‟ selections      within the range expected for commercial
maintained superiority over N197 and           cultivars (02948). It was also noted that
Kents, and „SL 28‟, „SL 14‟ and „SL 34‟        there was high level of field resistance to
showed remarkable productive capacity          CBD and leaf-rust, and low frequency of
than many other selections with a high         off-types characters (04810).
proportion of grade „A‟ beans (12622,
12623, 16648, 12624, 16649, 12625,             Irrigation to enhance production
12617, 12618, 13651, 13652, 13654,                 Various forms of irrigation treatments
13676, 13687, 13688, 13691, 13707,             have been utilised with varying results in
15160).                                        coffee production. Excessive irrigation
   Some selections (e.g. „SL 30‟, „SL 14‟,     reduced crop yields, hence the need for
„SL 17‟ and „SL 19‟) were noted to be          irrigation to be re-evaluated. Trickle
very susceptible to leaf rust and were not     irrigation was utilised mainly on late crops
suitable for general distribution, (14209,     (01633). The overall effects of overhead
13707, 14213). Blue Mountain selections,       irrigation on yield was a 3.6 percent
and „SL 34‟ were also noted to give            increase. Long term effects indicated that
appreciable yield with 55 percent grade        higher irrigation rates did not increase
„A‟ beans (14501). „Geisha I‟ and              yields significantly over the lowest rates
selections from it had small bean sizes,       and interval effects did not differ
but had considerable resistance to leaf rust   significantly (04811, 13980, 14558,
and CBD (14529, 15041, 15161).                 13741). In comparative experiments, basin
                                               irrigation was superior to both overhead
                                       Agronomy                                        9

and trickle irrigation. Further, trickle       significant effects on yield. Two
irrigation produced higher coffee yield        intermediate irrigation regimes (after 4
than overhead irrigation (05494, 238969,       and 8 weeks) did not significantly affect
239986, 244591, 244777, 300021, 351).          yield levels of coffee (19734), while
    In other experiments, trickle irrigation   trickle irrigation produced a late crop and
outperformed overhead and ground               stimulated disease incidence, (19735,
irrigation and one emitter between two         229693, 235752).
plants gave better results (06414, 05992,          Continuous records on irrigation
21695); and the growth components as           timing and application rates indicated that
well as yields needed to be recorded           there was a positive correlation between
(05992). A low level of irrigation proved      yield and interval (r=+0.72); and that leaf
much better in modulating growth of            temperature,      transpiration,   stomatal
coffee trees, (06070) and the maximum          conductance consistently indicated that
number of flower buds were produced by         irrigation ameliorated the effects of heat
trees that were irrigated only when            stress during the hot dry period (17637,
moisture level fell below 50 percent, but      15547, 15145, 15312). Trees receiving
with a decrease in flower buds, where          trickle irrigation during the dry hot
trees were not irrigated at all (06125).       months maintained a near favourable
Uncontrolled irrigation further results in     water balance (15307, 15284, 22101). It
lower strata getting over-saturated, thus      was suggested that overall, information on
causing adverse effects on the root            leaf growth rate, which is an integral
activities and trees in general (06416).       component of productivity of coffee,
    In terms of dry matter production,         suggests that it should only be irrigated at
trickle irrigation produced more wood          - 20 bars leaf water potential, as it is the
than basin or overhead irrigation. It was,     critical point when growth ceased
however, noted that it was necessary to        (237322). Irrigation increased clean coffee
irrigate at varying soil moisture deficits     yields and the proportions for grade `A'
and to maintain moist soils all the time       beans significantly (237233, 812).
(243378, 799, 351, 9597, 242894, 243079,
06865). Optimum overhead irrigation was        Interactions of cultural practices
determined, and it was shown that                  Various cultural practices have been
applying 38 mm at 21 days intervals            tested for their suitability in enhancing
optimised irrigation (11543). The greatest     coffee yields. Among those cultural
response to nitrogen was noted where           practices that have been investigated and
irrigation was applied as often as             reported are mulching, weeding, pruning,
necessary by overhead sprinklers. Bean         cultivation, irrigation, shade provision and
size increased with increasing frequency       nitrogen availability. Generally, mulch
of irrigation (13467, 817, 13729).             increased yields by 27 percent, while
Techniques for monitoring irrigation and       nitrogen fertiliser, overall, produced 23
the need for being able to apply irrigation    percent increases of clean coffee. Coffee
to a known depth using overhead                under a multiple stem system of pruning
sprinklers has been discussed (21526,          yielded more than that under an uncapped
235794, 235752). On high density coffee        multiple system, while the overall effect
plantings, although nitrogen levels and        of absence of mulch and irrigation was a
intermediate densities did not have            significant reduction in the percentage of
significant effects on overall yields,         grade „A‟ sized beans and the overall
different irrigation regimes produced          effect of nitrogen was to lower
                                        Agronomy                                      10

significantly the percentage of grade „A‟       reduce the biennial bearing characteristics
beans (15368, 06175, 06622, 06781,              (14202).
11745, 12361, 13739, 02947, 14202,
15281, 15485, 15247, 15171, 15151,              Pest management
15154, 15014, 14645, 14204, 14203,              Fungicide applications
15542,       16061,      16126,       16248,       Records of fungicide use and
16816,16939, 17966, 19428, 19432,               recommendations for the control of leaf
201990, 20114, 20582, 20590, 21076,             rust and other pathogens date back to
9186, 9189, 9183, 789, 713470, 677, 676,        1914 and copper sprays which are widely
660, 49, 34693, 34294, 235052, 22073,           used have been chemicals of choice for
236128, 236514, 236437, 236777,                 quite some time (02903, 04888, 11558,
236788, 236820, 236935, 237003,                 11624).
237075, 237093, 237099, 237445,                    The long term affects of copper sprays
237424, 241083, 243528, 2900, 300550,           on tree growth and cropping have been
31156).                                         reported and the persistence, distribution
    Clean weeding gave the highest yields       and residual effects of copper in the soil
of clean coffee in most years (13746,           and the plants have been largely
12361). However, some cover crops were          determined. All copper formulations
recommended for inclusion in coffee             (Bordeaux mixture, Kocide, Copper
stands, e.g. lupins which were noted to         Nordox, Cobox and Procide) have given
raise yields significantly (13720, 12361).      significant control of CBD. Copper
The presence of tall weeds during the long      treatments were noted to result in longer
rains led to disastrous reduction in the        primary shoots (04888). However,
yield and further, there was no difference      favourable penetration, distribution and
between implements used for weeding             good cover by the spray is of critical
(13978). It was further noted that clean        importance (05993, 15283). A great
weeding required 5 - 6 cultivations per         number of fungicide formulations have
year. There was no significant response to      been evaluated against coffee diseases and
mulch where a forked hand hoe had been          new formulations continue to be evaluated
used frequently. In the absence of mulch,       as they are released (21098, 20454,
however, a „Rotavator‟ appeared to have         21879, 20082, 05996, 228243, 22072,
adverse effects on soil structure (15281,       231038). Additionally, field trials with
533, 534). Mulch, in alternate inter-row        new chemicals recommended for leaf rust
plots gave the highest yield (15377) and        and other disease control have been
as a result of clean weeding highly             undertaken for many years (235870,
significant overall increases in the yield of   235873, 236351, 236025, 236366,
clean coffee were obtained (15539).             236583, 236850, 2368881, 237045,
    The use of shade trees on coffee trees      237043, 237469).
has been practised for quite some time,            Long-term routine applications of
and results indicated that total chlorophyll    fungicides in coffee have resulted in high
content, leaf water potential, transpiration    concentrations of copper in plants, litter
and stomatal conductivity decreased as the      and soils, but generally no phytotoxicity
distance from shade trees increased, but        has been reported (242349, 237400,
yield did not differ significantly with         246342, 9230, 238714).
distance from shade trees (17912,
                                                Other pest control strategies
201990). Early pruning did not affect the
                                                   Disease resistant varieties have been
mean annual yields, but seemed to slightly
                                                evaluated and these indicated potential for
                                       Agronomy                                        11

identification of genotypes suitable for       recommendations on fertiliser use are
specific conditions, with hybrids showing      made (02620, 02895).
some superiority. Indigenous natural
enemies seemed to have some impact on          Foliar sprays
Antestia spp. (17928, 19622, 20013).               Significant increases in leaf dry matter
   Coffee berry diseases and leaf rust         and increases in nitrogen were recorded
constantly cause considerable yield loss       for many foliar fertiliser applications and
and the long-term control strategy, that       some other fertilisers also contributed to
has occupied researchers for quite some        leaf K, Ca and Mg (02910). Additionally,
time, has been breeding for resistant          fresh and dry weights of leaves, stems and
genotypes, since the use of fungicides         branches increased with increased foliar
offered only temporary relief (237069,         feed concentrations and a slight increase
20078, 237299). Home-made greases              in coffee yields was noted (06222, 06734).
were used to trap ants (17485). Organo-        Urea and copper, used as a ground
phosphates      and    pyrethroids    have     application, and as a low-volume spray
continuously been evaluated for the            had some little influence on the level of
control of a number of insect pests, some      cropping (15046) and stem diameter
with spectacular success, (17342, 15285,       (15046, 19441, 21508). Generally, copper
06116, 230457, 235678, 235844, 237046,         spray combinations were most effective at
245712, 34322, 386, 432, 237454, 33252).       the end of the long rains (15381, 15245).
                                               It was, however, also noted that copper
                                               solutions greater than 5 mg/kg in the soil
Nutrition                                      culture resulted in stunted plant growth,
                                               severe necrosis of roots and leaves and
    Nutrient contents of new vegetative        were a hindrance to nutrient translocation,
growth and mature leaves and plant             whereas phosphorus treatments from 140
densities and soil analysis can be used as a   to 240 mg kg-1 and phosphorus and copper
basis for calculating nutrient requirements    treatments (at 1.064 mg kg-1) as well as
and the approximate quantities required in     copper in sand culture separately
each part of the plant correlated to give      promoted plant growth (15170, 18482,
the weight of nutrients absorbed per tree      19541). It was also noted that whereas
(20491, 16252, 06630).                         calcium and phosphates applied along
    With the prime objective of identifying    with nitrogen foliarly just before the onset
fertiliser combinations for different agro-    of the rains did not give consistent results,
ecological zones that would give the           that nitrogen alone sprayed before the
highest coffee yields and coffee of high       onset of the dry season gave a 30 percent
quality, a great deal of work has been         higher yield of clean coffee (05984).
done on chemical fertilisers that provide          Foliar feed applications were shown to
nitrates, phosphates, potassium, calcium       have effects on the nutrient status of the
and magnesium. Additionally, organic           coffee tree, with a strong tendency for leaf
fertilisers (farm yard manures, mulch and      N and K to be withdrawn from the leaves
other wastes and residues) and foliar          during berry expansion and ripening
sprays have been evaluated (15021,             stages (16247, 655). Other highly
20083, 202249, 520). It has been indicated     significant responses to foliar application
that both foliar and soil analysis are         of nitrogen and magnesium were noted,
needed to determine deficiencies before        whereby foliar application of nitrogen
                                               increased yield by 25.2 percent, while
                                        Agronomy                                      12

foliar application of magnesium reduced         per acre (17257). Further, foliar
yield of clean coffee (02890) and               applications showed that mulch treatments
application of a complete NPK mixture,          effectively raised soil reactions (pH)
applied six times a year gave a significant     (19520, 19524). The ground-applied P
response (02979, 03019). Further,               only slightly increased the soil reaction
magnesium and nitrogen seemed to favour         (19524, 19530). Comparisons of straight
girth increment, nodes on bearing               nitrogen fertiliser application with
primaries, leaf nitrogen and leaf               complete NPK and foliar sprays of similar
potassium, while phosphorus supply was          nutrient composition showed low yields in
related to leaf phosphorus (03021, 06466,       the unfertilised coffee plants, whereas
15820).                                         there was no significant difference in
    The use of NPK fertiliser improved          yields among the treatments (21873,
foliar P status and foliar application of       21904, 22047, 237173).
NPK gave better results than ground                 Residues from methane gas generators
application in terms of K utilisation           and fertiliser trials indicated that these
(15442, 16244, 16245, 34149). Further, it       artificial fertilisers were capable of
was noted that ground-applied K was not         increasing yields by 40 per cent, and in
utilised as effectively as foliarly applied     the absence of manure increased yields by
K, which may affect the absorption of P,        30 percent (22074). Further, methane
thereby reducing the yield generating           plant sludge was noted to raise pH, Ca and
potential of the nutrient and contribute to     Mg contents in the topsoil and subsoil
poor yield responses (15445). It was also       (529). Liquid manures gave a significantly
noted that the proportion of grade „A‟          negative response, while artificial
sized beans was higher where part of            fertilisers and cattle manure gave
annual fertiliser application was as a foliar   significantly positive responses (238211).
spray rather than as a ground application
(15475, 16257). Other observations              Manures and chemical fertilisers
further confirmed earlier results that          Interactions
close- spaced coffee required higher doses          In trials to investigate the effects of
of N and P when compared to                     planting hole size and farm yard manure
conventional spacings. Coffee yield             (FYM) on coffee establishment, it was
increases due to nitrogen application were      noted that the largest hole was
obtained from application rates of 200          consistently best in terms of yields given,
kg/ha and 450 kg/ha N (17258). Other            but the differences were not significant
results confirmed earlier observations that     (02939). Other trials indicated that
the highest yields of coffee would be           methane       gas     plant    residues, in
expected where phosphorus was applied           combination with cattle manure and
partly through the ground and partly            artificial fertilisers did not seem to have
through the leaves in combination with          effects on yield and quality of coffee
mulch (17260).                                  (02966). Farm yard manure was noted to
    It was also noted that trees treated with   improve overall soil properties and the
NPK foliar spray continued to maintain          combination of farm yard manure,
high levels of N, P and K, thus confirmed       phosphorus and calcium was more
earlier findings that the applied foliar feed   effective than most other plant
had effects on the nutrients status of          micronutrients (03018, 01632). Cattle
coffee trees and that the effective             manure alone increased soil levels of
application rates did not exceed 5 litres       sodium, potassium, magnesium and
                                          Agronomy                                       13

phosphorus but calcium levels were not            mulch and nitrogen fertilisers applied
significantly affected (03038, 03052).            together are not an economic proposition
Application of both cattle manure and             in mature coffee trees and that either of
chemical fertilisers gave the highest yield       the two should be applied alone (13921,
(04098), whilst coffee husks (cofuna) was         14176). It was generally observed that the
inferior to cattle manure with regard to          application of two 4 gallon tins of manure
enhancing height of coffee trees and the          per tree each year increased mean annual
number of branches (04861).                       yield (by 6.31 percent) significantly
    Results of some long-term experiments         (13940). Urea failed to raise the yield of
indicated that manure application did not         coffee significantly (14186, 14561) and
significantly affect quality of coffee and        with the application of urea solutions of
the availability of nutrients P, Mg, and K        up to 33 percent w/w concentration as a
was enhanced by manures (04863,                   spray, some slight scorch was apparent
14181). Interactions between organic              (14566).
manures and artificial fertiliser treatments          Soil analysis indicated that levels of
indicated that a significant reduction in         exchangeable potassium and magnesium
grade „A‟ beans was realised following            were lower than those of calcium and
the application of artificial fertilisers         phosphorus, with the application of
(06015, 06426). This contradicted other           ammonium sulphate, while levels of
studies, where artificial fertiliser increased    exchangeable potassium in the soil were
the yields by 42 percent and cattle manure        raised      substantially   through      the
and sludge increased yields by 31 percent         application of cattle manure (15273). It
and 22 percent respectively (06777,               was further observed that cattle manure
13702). A similar trial with six organic          had a beneficial effect on growth of
manures and two artificial fertilisers gave       seedlings, but inorganic and organic
results similar to those above (06867,            fertilisers had a negative effect. Thus
15484). Where two 16 tonnes/ha cattle             coffee seedlings planted in a compost of
manure had been applied, there was no             good topsoil, sand and cattle manure and
justification for the partial substitution of     with single superphosphate mixed with
artificial N fertiliser (11566, 12408,            the compost did not need any further top-
13473,      13736).      Though       nitrogen    dressing for good plant growth (21890,
application usually leads to enhanced             15359, 17798, 17790, 17813, 485).
yields the relationship between rate of               Reports on high density coffee, sizes of
application and the mean annual response          planting holes and rates of manure
is ill defined, but it represents a return of     application indicated that responses to
about five times the cost of fertiliser           farmyard manure and the largest holes
(14628, 14631). In the absence of                 gave best results in terms of proportion of
nitrogenous fertilisers, cattle manure            grade `A' coffee beans (17349). Also, the
increased the yield of coffee significantly,      application of dairy sweepings equivalent
thus the application of two 4 gallon tins of      to the application of farm yard manure
well composed cattle manure per tree              made large quantities of nutrients
raised the mean annual yield of clean             available and increased growth (17813).
coffee (15026, 15030, 06668), while none          Further confirmatory trials indicated that
of manurial treatments had significant            manure applied alone at a rate of two
effect on the proportion of grade „A‟             debes (local measure of about 20 litres)
beans       (16262,       32063).         Later   per tree per year gave satisfactory results,
experimentation further confirmed that            beyond which a decline in coffee yield
                                        Agronomy                                       14

was noted (17998). Composted husks              ground cover resulted in a significant
(cofuna) increased exchangeable base            yield increase of both clean coffee and
ratios, Ca, Mg and K over cattle manure.        grade „A‟ beans (15016). However,
A similar trend in pH increase from low to      generally, all mulching treatments
high rates was reported (18001). Further,       significantly increased the clean coffee
it was noted that cofuna was inferior to        and grade „A‟ coffee yields (15021, 658).
cattle manure, and that manure raised           In the Kitale area, however, mulching did
levels of exchangeable K, Mg and Ca in          not significantly affect yields (15015).
the topsoil (673, 32633). This confirmed            Sucker growth measurements indicated
earlier results.                                enhanced growth in mulched plants
    It was also confirmed that phosphatic       (15025), but other results indicated that
fertilisers in the planting hole and cattle     yields were not affected significantly
manure application early in the tree life       (15245). Chemical and biological analysis
had a depressing effect on yields, except       of topsoil samples suggested that mulch
when manure was applied annually at the         decreased     soil     acidity,    increased
rate of two four gallon tins per tree           potassium, magnesium and phosphorus,
(15143, 672, 674). There was further a          whereas nitrogen supply in the soil was
tendency for a rise in nitrate to follow a      decreased (15141, 668, 805).
rise in moisture content that may be                In other similar studies involving
conserved by mulch or cattle manure             feeder roots, magnesium content was
application (300440). A farm yard manure        higher in the mulch/sodium nitrate used
substitution trial in which artificial          than it was in the mulch/urea treatment,
fertilisers were used indicated that the        while calcium and potassium increased in
highest manure treatment (4 debes per           the feeder roots under mulch application
tree) gave lower overall yield. It was          (15302, 670). In addition to various types
further shown that 2 debes of cattle            of nitrogenous fertilisers, mulch increased
manure per tree seemed to substitute N          the overall yield of clean coffee by 24
fertiliser rates up to the highest level used   percent and calcium ammonium nitrate
(140 kg/ha) (32654).                            provided a 16 percent yield increase
                                                (15165). The overall effect of mulch
Mulch and chemical fertiliser                   treatments was an increase of bean size
interactions                                    especially in the alternative inter-row
   The effects of various mulch                 mulch regime, which increased the
treatments have been were studied since         proportion of grade „A‟ beans by 3
early 1950's (300293, 15386). Mulch             percent (16069, 15168).
placed between alternate rows increased             Mulch applied between all rows
general mean yield by 33 percent and the        resulted in increased yield of between 45
quantity of grade „A‟ beans rose by the         percent and 57 percent and production of
same proportion (12333). Napier grass           large beans was increased by between 72
mulch increased leaf phosphorus values in       and 85 percent. Soil analysis data
both first mature and second bearing node       indicated that mulch with cattle manure
leaf samples (13682). It was also indicated     raised topsoil phosphorus, exchangeable
that Napier grass mulch and nitrogen and        potassium and increased soil sodium as
maize stover gave superior results (13699)      well as influencing calcium levels, and
and that mulch and copper sprays led to an      thus improved leaf composition, crop
increase in annual yield (14537, 15060).        yield and soil moisture (15294, 15431,
Of the mulch treatments, 50 percent             15560, 16108, 16657, 15260, 16655,
                                      Agronomy                                       15

15262). Further, the use of magnesium         that the response to mulching was
without mulch depressed coffee yields         enhanced by addition of magnesium
(15263). Overall, nitrogen treatment          (13961, 13963, 13969). Other trials had
produced significant yield increases and      also indicated that there was no indication
this response was more pronounced in the      of any benefits from the use of nitrogen or
absence of mulch (10689, 13126). High         magnesium fertiliser (13976, 14523,
levels of magnesium were recorded in all      14563, 300539, 3732).
plots. Mulch treatments also increased leaf       The processes through which N
nitrogen, the response being marked in the    modifies some of the processes were
absence of fertilisers, thus showing, a       studied, with particular emphasis on the
negative interactional effect between         effects of N on stomata, transpiration
mulch and nitrogen on leaf nitrogen           water potential of leaves, the levels of
levels, similar to the effect on crop         bound water and chlorophyll (400).
response. Similarly, increased leaf levels    Earlier, an increase in magnesium,
of phosphate and potash and decreased         following the use of nitrate in the absence
levels of calcium and magnesium were          of Napier grass mulch had been noted.
noted (03054, 14635), There was,              Napier, on the other hand, was noted to
however, no benefits when nitrogen and        increase significantly, leaf potassium,
mulch were applied together (04127,           whilst leaf magnesium and calcium were
14172, 14170, 14174).                         decreased, thus confirming earlier finds,
    In other experiments, it was shown that   where magnesium deficiency symptoms
mulch and nitrogen influenced chemical        appeared in mature leaves (14577).
properties of soil and dry weight and         Further application of magnesium in the
nutrient contents. Mulch increased            absence of mulch resulted in the reduction
phosphorus in the 0-6, 6-12 and 12-18         of clean and grade „A‟ coffee yields,
inch layers and increased calcium in the      (14993, 9202, 300538, 300556, 300543).
upper two layers, whilst nitrogen                 Mulch was noted to significantly affect
application depressed phosphorus, pH, K       total pore space of soil free drainage pore
and Mg in the three layers and decreased      space, water tension and water
Ca mainly in the 0-6 inch layer. The          acceptance. These parameters were
acidity (pH) and manganese in the 0-6         greater in mulched than in unmulched
inch layer were increased (06504). The        treatments (12688). Other mulch and
effective amounts of mulch treatments         nitrogenous fertilisers effects, e.g.
were between 33 and 55 percent (14631,        magnesium and calcium interactions were
06616, 06618, 06619, 13473, 06679,            confirmed to produce no significant
14184). Response to mulching was not          differences between methods of mulching
significant, but application of 50 percent    (13656, 13659, 13677, 15378, 15385).
mulch cover at the higher rate of nitrogen    Interactive effects of mulch, irrigation and
and 67 percent mulch cover at lowest rate     cattle manure have been extensively
of nitrogen significantly increased the       reported (16264). Cattle manure and
yield of clean coffee (15004, 15004,          mulch increased grade „A‟ yield by 27
15007, 06663, 22004, 541). Napier grass       kg/ha and 48 kg/ha respectively when
mulch was shown to give superior results      applied singly whereas application of
and had effects on magnesium and              manure and phosphate increased yield by
calcium nutrition of coffee where mulch       30 kg/ha and 42 kg/ha respectively and 1
and „Calmag‟ had been applied (06679,         kg/ha when applied together (16812,
327, 06736). It was, however, also noted      16813, 16814). The response to mulching
                                       Agronomy                                         16

appeared to have been enhanced by              nitrogen, exchangeable K, Ca and pH.
addition of magnesium and the reduced          Physical structure was also improved,
yield tendency was apparent where              which increased the percentage of water
magnesium was applied to unmulched             stable aggregates and percent pore space
coffee (326).                                  (32346, 300344). The influence of mulch
   Mulching with Napier grass and              on the exchangeable soil K had been
banana leaf trash enhanced soil nutrient       reported (544). Studies conducted on
content and the rate of accumulation of        mulch materials indicated that vegetative
additional plant nutrients in the mulched      grass mulch was superior to artificial
soil. Thus mulched plants were better able     polyethylene mulches with respect to soil
to withstand an abrupt fall in soil nitrates   moisture conservation. In addition, grass
(300518).                                      mulch increased soil moisture content, soil
                                               organic    matter,    magnesium        and
Mulch materials                                potassium, while increased potassium
    The efficiency of different mulch          might result in induced magnesium
materials was investigated and was shown       deficiency (300295, 300296). Mulches
that mulch persistence was a critical          can also be used to control soil
consideration (18302, 237309). Generally,      temperature under coffee and polythene
however, no consistent differences in          mulches can be substituted (237309,
respect of soil moisture conservation          237298, 300314). Other materials used
efficiency were noted and figures of yields    were Elephant grass, (Pennisetum
of dry matter, quantities of plant nutrients   purpureum), Guinea grass (Panicum
removed per tonne of dry matter yields         maximum)       and    thatching      grass
were subject to wide variations (17792,        (Hyparrhenia sp). Banana leaf mulch was
17807, 300535). There were no significant      most effective in weed control (300519,
differences in coffee growth, root             300520, 300542, 300543, 300545,
distribution and yields between different      300549, 300551, 300552).
types of mulches (18490, 201573). In the
absence of nitrogen, maize stover applied      Chemical fertilisers
as mulch in January was superior to                Full details of types and quantities of
Napier grass. However, a combination of        fertilisers suitable for different soil types,
Napier grass mulch and CAN was a               regions and coffee             yields have
superior treatment (15011).                    continuously         been       given       as
    Various     forms     of    Pennisetum     recommendations to farmers (237347,
purpureum produced the highest yields of       242299, 300294, 237468, 242279,
dry matter per acre. Other grasses showed      237303, 237374, 237435, 237442,
considerable potential. The local P.           237451, 2374457, 17943, 17978, 19534,
purpureum decomposed fairly quickly,           202602, 22009). Scientific analysis of the
but was inferior to Cymbopogon spp.            nutrient requirements of coffee soils and
which gave a mulch of longer persistence.      the way in which these can influence
Napier grass was also noted to have            coffee yields and coffee quality has
potential for enhancing production, almost     identified       the      most      important
similar to P. purpureum (15390).               macronutrients as nitrogen (N) and
    Banana leaf trash has also been            potassium (K), followed by calcium (Ca),
extensively tried as a mulch material. It      magnesium (Mg), sulphur (S) and
was indicated that this trash significantly    phosphorus (P); while the most critical
increased levels of soil organic matter,       micronutrients       include     iron    (Fe),
                                        Agronomy                                       17

manganese (Mn), boron, copper, zinc and             Magnesium was noted to significantly
molybdenum (15292, 13927, 804). The             affect the type and quality of roast and
frequency of application of these               thus the application of magnesium, as
chemicals, especially the macronutrients        „Calmag‟ resulted in dull roasts and
has been defined. For nitrogen, four            improved quality of roast (15021) while
applications per year gave higher               iron, manganese, zinc, boron, copper, and
proportion of percent grade „A‟ sized           molybdenum chelate applications did not
beans (202242, 237111, 235217, 236034,          alter significantly mean yields or the leaf
236821, 237318, 02892, 516), while              dry matter. However, copper chelate
fertiliser levels, irrigation and plant         appeared to have some benefit, as shown
densities and their interactions were not       in overall stem diameter increment
significant (02729) and the application of      (15084, 15329, 15248, 18482, 02924).
50 kg/ha of N was most economical when          The extensive use of copper containing
applied twice a year (04121, 04823,             fungicides, however, may lead to
16251, 16250, 16249, 15483, 15481,              accumulation of high copper levels in the
14989, 14493, 05507, 06022, 06027,              soils, which may lead to reduced
06123, 06176, 06421, 06433, 06778,              branching, thickening and abnormally
06866, 13943, 13944, 13966, 15331,              dark coloration in the root system of many
16885, 17341, 17261, 9200, 826, 519,            plants (19541).
32671, 300540, 241584, 300427, 336,                 Methods to extract phosphorus, which
237311, 237150, 237104, 237077,                 could produce consistent results for soil-P
237059, 234594, 22102, 22079, 22017,            and hence show consistent relationship
02816).                                         between soil-P and that in coffee plants,
    Through leaf, soil and yields analyses,     indicated that as many as 10 techniques
the highest application of nitrogen (400        could be adopted (02876). Through these
kg/ha) gave the highest yields of clean         techniques, it was noted that radioactive
coffee at highest tree densities; and leaf        P remained in the finer roots and did not
nitrogen increased with N treatments at         move to the growing tissues in the canopy
most sites. A trend in increasing               and that limited growth of coffee
exchangeable (HP) with N treatments was         seedlings may have brought about the
also noted (02922, 04825). Nitrogen alone       limited uptake observed (03083). It was
and in combination with phosphorus was          further noted that P in the leaf dry matter
also noted to be favourable, whereas            decreased soon after application, but
nitrogen at 100 - 200 kg/ha and potassium       started to rise after subsequent dressing
combination did not show any increase in        with 250 g of the fertiliser (02899). It was
yields (02923, 02925, 02967, 14843,             further noted that high levels of soil P may
02976, 02983, 03017, 03084, 04050,              induce the shortage of such nutrients as
04095, 05727, 06025, 14637). The best           Mg (06105, 664). Further, it was noted
combinations of fertilisers containing          that soil phosphorus supply was related to
nitrogen, phosphate, potassium, calcium         leaf phosphorus and to the bearing
and magnesium were investigated (02876,         primaries nodes, leaf nitrogen potassium,
02819). It had been shown that both the         calcium and magnesium, where nitrogen
ammonium and nitrate fertiliser treatments      favoured girth increment, nodes on
increased coffee yields slightly, but where     bearing primaries, leaf nitrogen and leaf
mulch had been applied, the yield               potassium (04608, 02882, 15820, 15830,
appeared      unaffected    by     fertiliser   230138, 236515). Some antagonistic
treatments (15020, 02917).                      effects between potassium and magnesium
                                        Agronomy                                       18

in coffee nutrition were noted, where there     16252, 16136, 15434, 16246, 15375,
was a wide difference in the amounts of         22079). Time of application of nitrogen
the antagonistic counterparts present           fertilisers was studied (with ammonium
(06113, 544, 648, 662).                         nitrate applied in the long the short rains,
    In a national survey, particularly in       or foliar spray of urea) with a dry season
coffee growing areas, micronutrients            between the rains. Results indicated that
(boron, zinc and copper) were indicated to      application of 60 lb of nitrogen per acre or
be deficient in parts west of the Rift          other moderate rates of nitrogen fertiliser
Valley and interfered with yield potential      to the ground in the short rains was
in Bungoma, Trans-Nzoia and West Pokot          superior to the same rate applied to the
(06221, 14503, 802, 11564, 17332).              leaves in dry weather (14567, 14996). In
Further, it was noted that coffee yields        other trials, there was no significant
west of the Rift Valley had adequate            difference between rates of fertiliser
supplies of sulphur, while those east of the    application or between times of
Rift Valley had less sulphur, and that most     application (15033). The interaction
small scale farms had adequate sulphur          between N rates and application frequency
supplies. Thus, fertiliser for use in coffee    was significant (16260). Progressive
in plantations east of the Rift Valley needs    increase in frequency of application
to contain some sulphur (06117). In             resulted in better utilisation of nitrogen
relation to nutrient uptake, it was noted       (16263). Where phosphate was applied,
that in the zone of highest root activity,      potash decreased the yield in the absence
uptake increased with the rate of               of nitrogen, but gave increases in yield
application, the low rate of uptake             where low and high rates of nitrogen were
observed in some loam soils suggested           used. Where phosphate was not applied,
that the overall efficiency of utilisation of   potash had little effect on yield. These
P by coffee trees was poor and that water       interrelationships had been observed in
soluble P was released very slowly, thus P      earlier studies (06431, 300553, 06012,
in solution was insufficient to meet            06014). Generally, both potassium and
fixation by soil and uptake by the roots        phosphorus did not have a significant
(03084, 17493, 17494). Generally, the           effect on yield, but nitrogen significantly
highest yields were obtained from NPK           (P=0.001) increased yield (06109, 06223)
fertiliser combinations, with nitrogen the      and both ground and foliar spray
most important (06010, 04144), and that         combinations of NPK produced the
potassium, magnesium, sodium and                highest yield of grade „A‟ beans (06210,
calcium became more available with lime         06869, 239039, 9804). The optimum
application (04837, 17997).                     coffee yield was achieved through the
                                                application of single superphosphate
Time and rates of fertiliser application        fertilisers at the rate of 190 kg/ha and
   Nitrogen was observed to produce             coffee trees mulched and sprayed with six
significant increase in yield at 84 kg/ha       rounds of 2.5 percent phosphoric acid
and 127 kg/ha levels of application, while      (06466, 06779, 06783). In the absence of
at higher rates the increase obtained was       lime, phosphate treatment produced
not significant (231046, 20576, 21169,          overall a decrease in yield at all levels of
17803, 16062, 15332, 238212, 826, 671,          nitrogen application (13475, 17997).
657, 656, 300540, 300427, 337, 237311,          Where phosphate was applied, the lower
237284, 237104, 21873, 21171, 21169,            rate of lime decreased the yield of clean
202602, 19515, 19497, 19515, 16261,
                                      Agronomy                                         19

coffee, but higher level of lime had a            In further experimentation, it was
significant positive effect (13477, 17492).   shown that at both east and west of the
   Among phosphatic fertilisers used it       Rift Valley, there was a yield advantage in
was noted that overall yield increases        high tree density planting at about 2658
resulted from the use of double               trees/ha and that 100 kg/ha N was
superphosphate and basic slag treatments      adequate irrespective of the tree density.
(13934, 232040, 13943). Application of        However, the medium tree density of
magnesium in the form of „Calmag‟ up to       2658 trees/ha appeared most appropriate
the rate of 100 lb/acre did not have any      (1798, 32670, 496). Optimal density of
clear effect on coffee yield. However,        the hybrid arabica coffee F3 generation of
magnesium and calcium were noted to           „Catimor‟ was about 5128 trees/ha, whose
improve raw coffee quality and roast          fertiliser requirements were not different
quality.     Interactions    between    the   from the traditional types (200571). Yield
individual nutrients may, however,            increased linearly with tree density but
determine their availability (15040,          peaked at 5128 tree/ha (247887, 21493).
17815). Interactions of nutrients with        Analysis of leaf samples indicated that the
mulch are discussed at length by different    trees were well supplied with K, P and Ca,
workers (15042, 15050, 15427, 16258,          while soil results confirmed adequate soil
05232, 15192). It was generally noted that    fertility, especially of the topsoil (21865).
use of cattle manure or mulch affected        Although        normally      two     nitrogen
quality of coffee beans. Excessive levels     applications        had       earlier     been
of some nutrients were noted to cause low     recommended, another trial indicated that
yields, become toxic to the coffee plant or   splitting fertiliser applications into 4 times
cause poor coffee quality (15192, 15269,      gave higher yields especially in hedgerow
15477, 15480). Cattle manure, under           coffee (21984, 21988, 22078).
combined conditions reduced the positive          In other trials, it was noted that
responses to nitrogen fertiliser of clean     increasing levels of lime significantly
coffee per acre (15269). This confirms        depressed the percentage of grade „A‟
results of earlier experimentation (14563).   coffee. Low liming and moderate nitrogen
                                              rates (50 to 100 kg/ha) slightly increased
Fertiliser placement                          percent of grade „A‟ in response to
    Regarding placement of fertilisers, it    increased potassium fertiliser application
was shown that where the lowest rates of      (32653).
fertiliser were used it was important to
apply to the soil, rather than scattering
over the mulch (15037). The most
satisfactory response was produced where
nitrogen fertiliser was applied on either
side of a band of mulch 4½ feet wide, laid
along each side of a row of coffee trees
(15267). It was also noted that
accumulation of 32P occurred in leaves
sampled from the fertiliser placement side

Fertiliser and tree density
                                       Agronomy                                        20

Soil Factors                                   usually have a low pH and are poorly
    Good soil management provides              supplied with calcium and magnesium.
satisfactory environment for roots,            Soils with mixed crystalline and
suppresses weeds, maintains fertility and      amorphous materials are found within the
prevents accelerated soil erosion. These       high bracken zone and are generally less
factors are interrelated, in general, with     acidic and suitable for coffee production,
topography and need to be considered in        while soils dominated by kaolinite fix
coffee production (20092, 245191, 539,         phosphorus very strongly, and when
814). Certain soil parameters are crucial      phosphates are used in conjunction with
for coffee production. These parameters        organic manures or mulching materials, an
including      permeability      to   water,   increase in available phosphorus is
infiltration and available water were          possible. Other soils have mixed
determined in many of the coffee growing       crystalline mineralogy are suitable for
areas (500, 04853). Coffee cultivation and     coffee, fix phosphate less strongly and
cropping technologies in vlei soils            have high pH (15300). In chemical and
indicated that economic crops such as          biological analysis of coffee soils, it was
maize and Napier grass, could be obtained      shown that fungal growth was influenced
using camber bed cultivation (05226). The      by the level of ammonium nitrates in the
potential of vlei soils was further            soil (15254). A peak accumulation of
examined, and was noted that these soils       nitrates was obtained in the immediate top
were capable of producing Napier grass in      soil and a substantial increase with depth
plenty, when nitrogen and phosphorus           and time, during the first rainfall was
fertilisers and cattle manure were applied.    realised (17801).
A combination of these treatments gave             A non-mound building termite attacks
significantly higher yields than the sum of    vegetative materials used as mulch. The
individual treatment yields, thus, it was      termite soils showed lighter colour and
recommended that either ammonium               had very significantly higher pH values,
sulphate or double superphosphate or           or lower degree of acidity (17866).
cattle manure be applied in the early long     Nitrates were found to be accumulated at
rains (15116). Owing to highest figures of     higher levels of soil moisture between the
nitrogen throughout the soil profile           limits of permanent wilting percentage
(Kikuyu red loam coffee soil), it was          and field capacity levels (13931). The
concluded that added nitrogen was present      movement of nitrates can thus be followed
in organic form in the soil profile (15147)    in the upper 6 inches of the soil profile,
and that both nitrogen and phosphorus          through tracing the movement of chloride.
levels were variable between different         It was shown that in dry weather, nitrates
trials. Although biological phosphorus         and chloride appeared to move upwards in
analysis showed some consistency with          the soil profile to the 0 - 3 inch depth, and
chemical values, there was lack of any         that the leaching of nitrates and chloride
specific response for mature coffee trees      took place during the rainy season
(15290).                                       (15392). Ameliorative fertilisers were
    Soils classification recognised soils at   noted to be slow acting, and were applied
elevations above 7,500 feet and those          on topsoil and subsoil in the form of
between 6300 and 7500 feet above sea           carbonates      (15488).      When      these
level as ideal coffee soils. Soils dominated   carbonates and silicates were used, they
by amorphous material, such as clay            were effective in raising the pH of acidic
minerals derived from volcanic ash,            soil and thereafter there was a general
                                          Agronomy                                       21

improvement in the soil fertility status due      of the trials indicated that water
to applied fertilisers. Further, there was an     availability had great influence on leaf
increase of potassium, magnesium and              phosphorus values (12626, 20567, 15783,
calcium contained in ameliorative                 16758). A great deal of work has been
fertilisers; and released from fixation in        done on the values of different fertilisers,
the soil as available calcium and                 as suppliers of individual nutrients and
magnesium ions (15413, 801, 16259).               recommendations have been made to
Fertiliser applications based on soil             farmers. Chemical fertilisers containing
analysis, gave best results and an inverse        nitrogen, phosphates, potassium, calcium
relationship between clean coffee yield           and magnesium and soil treatments with
and      all    nitrogen-only      compound       lime, organic fertilisers such as farm yard
fertilisers; and ameliorative treatments and      manure, mulch coffee pulp and foliar
the percentage of grade „A‟ sized beans           sprays have occupied researchers time for
was noted (202367, 20458, 238782). In a           quite a long time (19502, 809, 02885). It
10 foot soil profile, it was shown that           was also found that cherry skins did not
neither the fixed nor the exchangeable            make good organic manure in coffee
ammonia differed significantly with soil          subjected to magnesium deficiency and
sample depths (15144).                            growing in soil with high values of
    Trials     on      optimum       fertiliser   available potassium, because of the high
requirements, tree density and growth             potassium and low magnesium contents
characteristics have been undertaken for          (15251, 17985). Other factors that may
quite some time (18451). Nitrogen,                influence the composting process of
phosphorus and potassium were noted to            coffee pulp are moisture, temperature and
be important for coffee productivity. The         duration of composting. The duration of
highest yield of coffee, (2254 kg/ha) was         composting decreased with frequencies of
produced with 78 kg/ha of nitrogen, and           turning (17989, 202422). Coffee pulp
generally there was a progressive yield           treatment did not appear to significantly
increase due to increased combination of          affect the levels of micronutrients Mn, Fe,
NPK fertiliser (19502). In other areas, e.g.      Zn and Cu contents of dry matter, but
Namwela, optimal N fertiliser ranged              there was tendency for Cu, Zn and Fe to
between 100 and 200 kg/ha (9469). In              increase with increasing coffee pulp
other trials, nitrogen treatments and             (15439). However, pulp treatments gave
density interactions effects did not give         highly significant effects, related to soil
significant differences. It could be              reaction (pH) exchangeable acidity (HP),
observed that yield responses to nitrogen         exchangeable K and extractable soil P, all
tended to be optimal at 200 kg /ha (809).         of these increased with increase in coffee
Fertiliser requirements for the compact           pulp (15439). Effective drying of coffee
and disease free Arabica coffee, „Catimor‟        pulp could be sufficient to allow for the
were not different from those for the tall        use of the by-product as component of
traditional types (9169).                         ruminant diet (18328) and as fuel products
    Soil amelioration trials indicated that at    (243833, 237381).
high lime rates, Napier grass mulch and
phosphates gave a significant positive
interaction between lime and phosphates
(02885). Earlier trials to identify the best
combination of fertilisers under different
ecological zones were undertaken. Some
                                       Agronomy                                        22

Intercropping                                      It was recommended that during the
                                               first 18 months after block stumping, high
Food beans                                     density coffee and 2 - 4 dry bean rows per
   Intercropping coffee with beans is at       coffee inter-row may be successfully
times a major practice, especially when        grown with the application of 80 kg/ha N
prices of both commodities fluctuate such      per season in high rainfall areas (32538).
that bean production becomes a profitable      Other     observations     indicated     that
venture. The 1.20 metre wide coffee inter-     intercropping coffee with beans increased
row space was found capable of sustaining      the proportions of grade „TT‟ and thus
high yield from 4 bean rows (00105).           lowered quality of clean coffee, due to soil
Double-row bean planting significantly         moisture stress (32547). After a survey
yielded more than single row planting,         that established that indiscriminate inter-
with coffee densities of up to 6667            planting resulted in substantial losses from
trees/ha, above which density there was        coffee, the Kenya Government revoked a
poor bean yield due to lack of sunlight        1981 directive allowing farms to inter-
(00940). Other experiments showed that         crop coffee plantations (237328, 247612,
significant response to nitrogen fertilisers   247692).
was more pronounced for 2-row planting
than 4 and 8 rows (02846). Although            Mauritius Bean
cherry yields seemed to be lower in               The Mauritius bean forms a dense
coffee/bean inter-crops, the extra crop of     growth, thus having a splendid cover and
food beans was received from plots under       mulch characteristics, but has a climbing
inter-crops (04802, 32772), these and          habit so that runners have to be kept off
other indications (06144, 06147) were          the coffee trees (17969).
such that inter-row space could sustain
food bean cultivation and production           Desmodium intortum
profitably. Bean plants around coffee             Under Desmodium intortum cover and
stumps were more vigorous than those           Napier grass mulch, highest coffee yield
further away, while at very high coffee        was obtained with Napier grass plus 120
densities, beans in the upper row were         kg/ha nitrogen fertiliser. D. intortum was,
more vigorous in growth than those in the      however, superior to grass mulch (02941),
lower row (15330). The overall                 in terms of clean coffee yields, liquor
performance of food beans was poor             quality, moisture content and proportions
where there was low pH and where partial       of sizes „AA‟ and „AB‟ coffee beans
coffee canopy shading was evident              (04865). It was further noted that where a
(16266). It was further noted that             D. intortum cover crop was planted, it was
intercropping bearing coffee with food         suspected that a starter nitrogen
beans had some adverse effect on coffee        application may be necessary for coffee
quality, but not to the clean coffee yield     inter-planted with the cover crop (16267),
(16268) and that intercropping food beans      and through comparison, Napier grass was
in high density coffee during the second       found to be more beneficial than D.
and third years of production was not          intortum (17348). Further, coffee with
feasible (17252). At all sites and seasons,    grass mulch and treated with 60 and 120
significant interactions between food bean     kg/ha/year performed better than coffee
rows and nitrogen fertiliser rates were        under a D. intortum cover crop (17939,
obtained (17253, 233663).                      22012), while a combination of grass
                                               mulch with 50 to 120 kg/ha nitrogen was
                                         Agronomy                                      23

much better than D. intortum cover crop          100889, 100935) and also mixed cropping
(18346, 32676). There was an indication          and agroforestry systems (228281, 651,
of    a    Desmodium/coffee      nutrient        228723, 241138, 241163, 241167,
competition, especially for N, P, and K          245767, 245799, 245802, 32782, 32790).
(20573). However, in comparison with             Although coffee was generally planted
Napier grass mulch, D. intortum gave             one to three metres away from the existing
more effective soil erosion control than         hedges on farms in the coffee-based land
grass mulch (9178).                              use system, most species were reported to
                                                 have adverse effects on planted crops, but
Inter-planting                                   timely hedge management controlled the
   Coffee seedlings were inter-planted to        hedge effects (32793, 32794), and most
make a hedge spacing and double plant            farmers favoured planting fodder hedges
population. Overall, the inter-planted           around the compound (32813, 32817,
seedlings made much better growth in             32755, 32760). In change of cycle, in
certain areas of high rainfall (06148,           hedge-row coffee, alternate row stumping
15337, 419).                                     gave the highest yields and the effects of
                                                 heads was not significant at any of the
Coffee and agroforestry                          sites (434).
   As sizes of farms were getting smaller            In trials on the effects of established
in the coffee zone, (of Embu) woodlots           shade trees on coffee growth, yield
tended to disappear. However, within             parameters disease and pest incidence, it
coffee plantations, Grevillea robusta was        was shown that chlorophyll content, leaf
found to be a common. Other species of           water potential and transpiration rates
trees were found as external and internal        indicated a decrease with increasing
boundaries as well as in woodlots                distance from shade trees. Clean coffee
(19862). Most farmers were aware of the          yield increased linearly (r=+0.61) with
distribution of a number of tree species in      distance from the shade tree (32766, 328).
the coffee zone of Embu (19868).
   Management problems with trees were           Fruit trees
numerous, either with pests, negative               Fruit trees screening coffee inter-crops
effects on crops or soil or hazards to crops     were papaw, passion fruit, apples,
or houses (19873). For conservation of           oranges, bananas, guava, mulberry,
soil fertility in coffee estates, coffee trees   avocados, loquats, macadamia and
growing on benches with certain grasses          mangoes. It was noted that coffee-guava
e.g. Hyparrhenia diplandra, Chloris              and coffee-banana inter-crops gave lowest
gayana produced significantly more clean         yields, while coffee/loquats had the
coffee than those on bench terraces faced        highest yields (17933).
with Napier grass (15172). In other
experiments, coffee grown on benches             Leucaena leucocephala
faced with H. diplandra and Paspalum                Under Leucaena leucocephala shade in
notatum produced high yields, whereas            the Western and Coast Regions, Robusta
Napier grass produced a severe adverse           coffee showed increased cherry yields by
effect on coffee, and reduced yield to very      a magnitude of 90 percent, where coffee
low levels (15187). Other anti-erosion           trees were under slight shade (21491).
measures that conserved soil humus,              Food crops
nutrients and moisture were terraces of             Most annual food-crop screening
different types (100427, 100580, 100592,         affected coffee growth and yield, some
                                      Agronomy                                        24

more adversely than others. Sweet potato          Growth regulators were screened for
and maize were observed to have adverse       growth regulation and control of flower
effects on coffee (32712).                    bud dormancy. Some were recommended
                                              for practical application, in an effort to
                                              regulate cropping and enhance coffee
Seeds and seedlings development               yield and fruit set, increase bean dry
                                              weight, regulate ripening and flowering
Seed advancement                              (03070, 05988, 06084, 04053, 06675,
   Coffee seeds were noted to germinate       237324).
fastest (in 2 days) when treated with             Trees showed marked growth during
indoleacetic acid (IAA) dissolved in          the rains, reaching a peak later in the year.
acetone, but the treatment appeared to be     In some areas, both multi-stem and single
deleterious to some seeds (19492).            stem trees showed a gentle growth
Further, it was suspected that dry            increase. Growth curves for unshaded,
atmospheric conditions may affect coffee      shaded, unwatered and watered trees
seed storage and germination capacity         followed      same     pattern,    although,
(05138). Effects of pre-treatment of seeds    generally, the rates of growth of multistem
with micronutrients on subsequent stress      trees were noted to be greater than single
tolerance of seedlings was investigated,      stem trees (15120). The absence or
and reports indicated that zinc and           presence of a crop had little effect on the
aluminium treated seedlings appeared to       growth of the tree throughout the year
resist drought better (440). Treatment of     (15265). In trees treated with gibberellic
seeds with IAA seemed to shorten the          acid (GA), growth rate was lower, and in
period taken for seeds to germinate (436).    combination       with     a    nitrogenous
It was further concluded that seed            compound, GA produced more fresh
advancement        treatments      elicited   weight of coffee cherry (15310).
physiological activity, which resulted in         Growth regulators that may increase
rapid seed germination, but did not           the rate of carbon assimilation have been
significantly influence seed viability        reported, and they may have potential in
(228071, 236548).                             increasing yields of Arabica coffee
                                              (15319,       17799,      18449).      Other
Seedlings development and tree growth         biostimulants, e.g. Ergostim have been
   Results of nursery experiments             known to influence tree growth, yield and
indicated that seedlings grown in large       quality of coffee (21288, 387, 440), while
size polythene bags gave far superior         cytozyme applications resulted in yield
seedlings, with respect to growth and dry     increase that was not statistically
matter production, while seedlings grown      significant (9051).
in beds were disadvantaged in many
respects (06065, 229883).
                        Processing and Quality

Pulping                                         importance to the quality of the resulting
                                                product (19434).
   Arabica coffee is wet-processed and
the removal of mucilage during coffee
processing is an important step in wet          Fermentation
processing of Arabica coffee. Mucilage is
a complex material and can be broken               Studies on various aspects of coffee
down through enzymatic reaction, and it         processing including coffee drying,
was shown that Ultrazym-20 could be             storage and fermentation have been
sprinkled on coffee at some stage after         undertaken and results reported (01788,
pulping (03087) with advantage. Water           06623, 13693, 235495, 235845, 237276,
with high concentrations of iron was noted      237144, 237109, 237192, 237271,
to be responsible for silvery skin in coffee,   237272, 243803, 3146, 32196, 32423,
due to oxidation of coffee constituents,        34077, 443). Attempts have also been
especially the polyphenols (04047). The         made to identify chemicals in coffee oils
case for and against re-circulation of water    (cafestol and kahweol) which undergo
in coffee pulping in Kenya have been            changes to give colour to coffee. Grey
discussed and reviewed, (236036, 236976,        colour predominates in high quality
237155).                                        coffee, whereas green colours may be
                                                obtained in coffee dried in the absence of
                                                sunlight (03088). Commercial enzymes
Grading                                         were used to quicken the process of
                                                fermentation, but was later abandoned,
   The quality of parchment coffee              and the importance of naturally occurring
produced by a new system showed no              enzymes          emphasised.         During
consistent difference in the quality of         fermentation, it was noted that there was a
coffee compared to an older process             density increase, attributed to the
(05245). Raw quality, rather than flavour       breakdown of mucilage, and a slight
and roast quality was noted as important        decrease of density after soaking. The
in defining coffee classifications (06671).     largest spread over the density range
The relationship of bean density to             occurred after fermentation (04070).
classification indicated that efficient            The relative importance of various
grading in the factory could result in          micro-organisms in the process of coffee
effective separation of materials, which        fermentation have been identified, and
could otherwise lower the final                 considerable variability in the relationship
classification of the coffee. It was also       between pH and depolymerase activity of
shown that pH of the liquor decreased           the extracts noted. During wet processing,
with the higher classification of the           and drying of beans, respiratory process
liquor‟s acidity, thus the pH of the water      can continue, leading to loss of dry matter
used in processing is of considerable           (13436). It was noted that fermenting
                                                coffee was a source of enzymes capable of
                                 Processing and Quality                             26

degrading pectic materials. Enzymes were      had moisture content of 20 percent. The
isolated from water used to soak              mechanical drier would therefore be used
mechanically cleaned beans (15176). An        for skin drying of coffee beans and at the
examination of fermentation procedures        final drying stage, in order to attain
and the resultant quality of samples          quality beans at the final stage and to
indicated a trend towards a better quality    avoid „onion flavour‟ that was common in
following a two stage fermentation            certain areas (379, 9427, 9233). The
procedure (15185). A considerable             permanent transparent PVC tent-type
proportion of mucilage was accounted for      structure was noted to allow sufficient
as glucose, arabinose and xylose with         light    to    bring    about     desirable
hydrogen being evolved during early           photosensitive reactions and was also
stages of fermentation, but the final         noted to be labour conserving (06087). It
quality of coffee was independent of the      was further noted that a complex
production of hydrogen (18536).               lipoprotein     occurred       in     large
                                              concentrations in the coffee bean, but was
                                              degraded during the sun-drying and was
Drying                                        completely destroyed during mechanical
                                              drying (06099).
   Coffee requires that it be dried to a          Covering parchment by a roof two feet
moisture content of 10.5 to 12.5 percent.     above the parchment resulted in good
Methods and machines for drying coffee        quality coffee, whilst parchment covered
have been tested and research on the          merely by folding hessian cloth over the
economics of using driers have been           top to cut out direct sunlight did not help
reported (237388, 239970, 21488). The         to produce good quality coffee (13434). It
prime aim of proper drying and storage is     was shown that damage was reduced by
to avoid spoilage and bad taste. Both the     pre-drying and increased by increasing the
farmer and the processor therefore need to    final drying temperature. The cause of
be involved. Drying systems, including a      damage to wet coffee was absence of
solar drying system, consisting of initial    sunlight, while visible light caused
skin drying, intermediate sun drying on       desirable bleaching of silver skin and
tables and final drying has been used for a   production of a blue coloration in the
long time (240492, 245741, 245742,            endosperm (15136). The importance of
245743, 245745, 245748, 245752).              the depth and frequency of stirring to the
Comparisons of sun-drying of coffee,          sun-drying layers of coffee was found to
under different water-proof covering          be important (15174). Damage to the
materials such as „Coflex‟ and tents,         appearance of wet processed Arabica
indicated that tents had advantages over      coffee was confirmed to be caused by
other materials, as they could be used        machine drying in the absence of sunlight.
during bad weather and they also              Other conditions, e.g. ventilation,
accelerated the drying period by 7 to 11      immediate drying or to over-fermentation
days (32536).                                 also seemed to be important in drying and
   In order to maintain quality, although     processing of Arabica coffee (15278).
mechanical drying was a faster method of      Further, machine drying at temperature
drying than the traditional sun drying, it    not above 120 °F to complete or precede
was found necessary to combine                the sun-drying stage in simple ventilated
mechanical with sun drying at an              bins to carrying damp coffee through
intermediate stage, which coffee beans        periods of rain and for final conditioning
                                  Processing and Quality                            27

was recommended (15278, 237310).               the liquor quality was negatively
Deliberate over-drying coffee and              correlated with classification. The raw
allowing it to re-absorb moisture appeared     quality was the most important factor
to improve coffee quality, a result that       taken into consideration in deciding
contradicted earlier findings (18538,          classification (06671).
243875).                                           It was observed that quality of coffee
                                               produced by co-operatives was superior to
                                               that from estates. On the average, coffee
Storage                                        beans from co-operatives were larger and
                                               heavier. Mean nitrogen and calcium
    Experiments on a number of storage         content was higher in estate coffee,
treatments (sacks, sealed cans, sealed bags    perhaps reflecting greater use of
made from thick and thin gauge polythene       nitrogenous fertilisers (15180, 228229,
and woven polypropylene sack materials),       228284). „Onion flavour‟ in Kenya has
showed that moisture content of the sack-      been shown to be correlated to the
stored parchment rose and after three          presence of propionic acid during under-
months this coffee had deteriorated while      water fermentation if the water used was
the rest of the samples remained good, and     dirty. This condition could be reduced
had low rate of change as demonstrated by      through a reduction in fermentation time
falling levels of carbon dioxide (06112).      or reduction in the extent of pre-washing
    There was evidence that sack stored        (15369, 244011, 278). In terms of coffee
deteriorated more quickly than those           oils, no correlation was found between the
sealed under nitrogen or air. Conventional     assessed coffee quality and kahweol
storage methods posed certain problems,        content for 20 coffee samples. Further,
leading to spoilage. Certain conditions,       beans which had double centre cuts were
including suitable temperature and             undesirable and had an adverse effects on
humidity, that need to be satisfied in         quality. These beans are normally
coffee storage have been identified            produced by ten year old trees in
(13431, 230693, 236232, 236358). After         smallholdings rather than by recently
noting a close relationship between            planted coffee, (12783, 15109).
storage       conditions    and      quality       A strong correlation was found
deterioration, existing warehouse design       between colour and total soluble
was modified and engineering design            extractives and the colour of liquors was
requirements for new warehouse were            very closely related to the total soluble
prepared in the mid-1970s (237399,             extractives (17823). The bean and cup
237437, 245744, 245750, 439, 236153).          quality of the cultivar „„Ruiru II‟‟ was
                                               found to be similar to popular commercial
                                               cultivars „SL 28‟ and „K 7‟ (202230,
Quality                                        201811).
   Quality factors (size, colour, quality of       In general, factory processing in the
raw type, centre-cut, quality of roast,        cooperative sector has been recognised as
acidity, body and flavour of liquor) have      a key element in determining the quality
been compared and analysed by a number         of coffee output (237219, 237232). The
of workers. It was shown that all quality      Kenya Planters Cooperative Union Ltd.
factors, except body of liquor were            (KPCU), generally takes care of transit
positively     correlated     with     final   coffee storage and milling facilities
classification and with each other, while      (237204, 236996). Discussions on sensory
                                  Processing and Quality                             28

evaluation of Kenya coffee have indicated      evaluation of coffee quality (32404,
it is one with high intensity of fruity        32405).
characteristic and this may be influenced
by roasting techniques (236996, 236125,
237337). The new cultivar „Ruiru II‟ was       Effluents
similar in quality to the finest of coffees,
SL28 (236997, 236998, 237037, 237058,              The disposal of effluents from coffee
237065, 237096, 237097, 237098,                processing factories causes concern in
237177, 237250, 237220, 237295,                relation to river pollution (230104,
237428, 239991, 239994, 32490, 32534,          234019, 236513, 236675, 236983,
244216, 245753). Some of the aroma             236991). Other concerns involve the
noted commonly occurring in Kenya were         storage of parchment coffee to avoid
identified as green, woody, fruity,            deterioration of quality (20032, 20039,
cereal/toast-like, malty, earthy, animal       20046, 200857). The coffee industry is
like, carbolic, burnt/smoky/ashy, winey        thus the most important industrial polluter
and buttery. These aroma imparting             in rural Kenya (241363, 241375).
chemicals in the raw or roasted bean could
be used as reliable objective indices in the
                Economics of Coffee Production

Estates sector                                  maize, beans and potatoes was practised,
                                                especially when coffee prices were low.
    The economics of coffee production          Other studies established that high-
have been analysed on the basis of              yielding farms had lower costs of
smallholders and estate-size groups,            production per kilo of clean coffee than
which are irrigated and non-irrigated, with     low-yielding ones and that the average
generally a show of improved production         cost of production of coffee in the
in irrigated estates (17973). Profit margins    smallholder sector was K£1786/metric
were noted to increase with estate size and     tonne which was same as KSh. 35.70 per
non-irrigated estates operated at a loss, the   kilo of clean coffee (04874, 15984, 15850,
magnitude of loss decreasing with               201384, 20226). For the various agro-
increase in estate size (17970, 32797,          ecological zones, yield level of 0.57 tons
15988, 05350, 32774). The gross net             of clean coffee per hectare was maintained
revenues are a product of production and        through the use of less fungicides,
coffee prices and it was again confirmed        insecticides, fertilisers and boma manure.
that the total cost of production was           In this same subsector, it was noted that
higher in irrigated estates than in non-        „mbuni‟ production was not an
irrigated estates (04893, 02970). It was        economically viable undertaking and
also noted that more efficient production       should be discouraged (17906).
of quality coffee may be attained by                Generally, the yield achieved by
raising the yield of coffee per hectare,        different groups (low, medium and high
reducing the cost of production and by          management)        showed      that  coffee
applying new techniques and methods             enterprises were still economically viable
(20049).                                        at farm level, if a farmer could produce at
    Mechanisation of production and             least 800 kg of clean coffee per hectare
processing are deemed to be techniques to       per year (17908, 17906). Further surveys
be employed in intensifying coffee              indicated that the smallholder farmer
production (20422, 20053, 20440). Field         remains in coffee farming by ignoring the
management factors are also seen as             valuation of family labour (04893, 04805,
important in successful coffee production       02971, 17975, 100090, 20022, 21373,
in the estates sector (201385, 20432,           21402).
237222, 237153, 228250, 32417, 34065,               In surveys on physical, biological, and
238110).                                        socio-economic factors that influenced
                                                smallholder coffee production, it was
                                                revealed that success in coffee production
Smallholder sector                              depended on the understanding of the
                                                importance of diseases, pests, weed
   Kenya's smallholder coffee sector            control, soil quality maintenance, inputs
current status and future have been             availability, labour availability and
reviewed (34473). Within the smallholder        working capital (18457, 18445, 245512,
coffee farms, inter-planting coffee with
                             Economics of coffee production                         30

14709, 14551, 13932, 06469, 06227,            matters related to quota and non-quota
02973, 11560, 236880, 21285, 21286,           markets. These procedures are reported in
21490, 21496, 245408).                        various working documents (237213,
   The understanding of the socio-            237216, 237221, 237225, 237227,
economic framework of the community,          237228, 237229, 237230, 237133,
improvement of the rural infrastructure       237134, 237135, 237137, 237145,
(including    extension     programmes),      237148, 237166, 237167, 137168,
communications       and       cooperative    237169, 237180, 237181, 237183,
operations were critical and should           237121, 237128, 237185, 237186,
precede agronomic practices development       237191, 237120, 237122, 237125,
(20032, 20027, 200851, 20385, 237211,         237234, 237237, 237339, 237242,
237153, 237176, 229892, 231761,               237244, 237252, 237256, 237257,
235871, 236158, 236158, 236203,               237259, 237262, 237263, 237264,
236349, 236484, 236368, 236676,               237268, 237269, 237270, 237274,
236490, 245041).                              237275, 237277, 237289, 237294,
   It was noted that about 600,000            237303, 237327).
households in Kenya were engaged in              Other bodies that have been involved
coffee farming throughout the country. It     in handling coffee on behalf of the
was further indicated that farmers could      farmers and cooperative societies are
break even, and even make a profit            Kenya Planters Cooperative Union
depending on yield achieved. The gross        (KPCU) and Kenya Coffee Growers
margins were positive for all smallholders    Association (KCGA) and their mandates
(242539, 242583, 244143, 244179). In          have been reported (237163, 237170,
most smallholder farms, agroforestry has      237289, 237123, 237129, 237130,
been noted to have potential for the land     243143, 237132, 237105, 237106,
use systems (244210, 244211, 244597,          237107, 237038, 236952, 236953,
244615, 244654, 32768, 32769, 32774).         236954, 245710, 245709).
                                                 The Coffee Board, KPCU, KCGA and
                                              the cooperative societies are a source of
Marketing policies                            information     related    to     technical
                                              recommendations, input supply payments,
   The Coffee Board of Kenya has for a        markets and prices. Various workers have
long time now been the sole marketing         reported on terms of reference and modes
outlet for Kenya coffee. The Board has        of working of the various bodies. The
also supported Coffee Research and            Board keeps abreast decisions passed in
Development in Kenya (237199, 237188,         international fora on coffee matters,
237202). The Board keeps abreast of           consumer demands, quality characteristics
coffee price fluctuations and facilitates     and factors influencing quality, deliveries
credit facilities, awareness of research      and patterns, and their relationships to
technologies         and        technical     coffee pricing, increased expansion of
recommendations and streamlines coffee        area of coffee, processing and marketing
payments to farmers which coincide with       systems, irrigation and spraying coffee
input expenditures and other non-crop         exports, production forecasts, coffee
expenditures (237203, 237205, 237206,         auctions, loans for coffee farmers from
237207, 237208, 237212). The Coffee           donor community (237038, 237047,
Board also liaises with the International     237053, 237057, 237060, 237062,
Coffee Organisation (ICO) and follows         237063, 237-64, 237071, 237080, 237081,
                               Economics of coffee production                           31

237091, 237094, 237095, 237100,                 prices (33171, 300650, 238581, 238643,
237102, 236980, 236984, 236985,                 238897, 239338, 239403, 239773,
236986, 236987, 236988, 236989,                 240867). The effects of the Kenya coffee
236990, 236992, 236994, 236995,                 boom of 1976 - 79 and fiscal response to
236999, 237001, 237004, 237007,                 the temporary trade shock were
237008, 237010, 237011, 237012,                 investigated and was shown that the boom
237015, 237016, 237017, 237018,                 induced a massive increase in public
237019, 237020, 237022, 237023,                 expenditure, far in excess of the increase
237026, 237019, 237020, 237022,                 in public revenue. The net effect on
237023, 237026, 237027, 237029,                 capital formation was negative because of
237030, 237032, 237033, 237034,                 the fiscal response that exacerbated the
237035, 227916, 2227919, 227920,                rise in relative prices of non-traded capital
227944, 236678, 236677, 236726,                 goods (240980, 241417, 241447, 241545,
236929, 236933, 236934, 236938).                242179).
    Women are actively involved in all              Foreign      exchange     earning    and
aspects of coffee production (237021,           compensatory finances through STABEX
227947). This is especially true in             has been documented and noted to be of
smallholder sector, and these women are         assistance to ACP countries in respect of
involved in planting pricing, picking and       compensation for export shortfalls
transport      to   factories.    Constraints   (237330, 237334, 237335, 237336,
associated with this mode of production         237339, 237342, 237343, 237357,
have been reported and the roles of             237358, 237360, 237361, 237362,
women, other labour and the farmers             237365, 237367, 237369, 237370,
organisations are presented (228085,            237375, 237377, 237378, 237379,
236930, 236939, 236940, 236941,                 237382, 237345, 238969). Through
236942, 236947, 236948, 236949,                 numerous        recommendations       during
236955, 236959, 236965, 236966,                 meetings of the ICO declaration of
236967, 236968, 236969, 237110,                 shortfalls and requests for increases in
237278, 237280, 237281, 237282,                 annual quotas have been made over the
237287, 237297, 237301, 237302,                 years by Kenya and other coffee
237312, 237314, 237320, 238567,                 producing countries (237383, 237385,
238676, 238676, 300627, 242539, 31469,          237386, 237389, 237390, 237393,
31920, 243471, 243497, 243575, 243797,          237407, 237409, 237410, 237411,
243798, 243800, 243802, 243874,                 237414).
244241, 244244, 244240, 244311,                     In Kenya current coffee marketing is
244357, 244436, 237465, 238035,                 now liberalised but before this step was
237477, 239403).                                taken the Coffee Board of Kenya was the
    On Kenya‟s economic policy with             source for coffee marketing. A few
respect to the world coffee market, it was      constraints experienced during this time
noted that Kenya‟s' past coffee market          focus on transportation of coffee from
policy did not promote the country's            various points to a central collection point,
growth, income distribution, monetary           the railway system, the roads inadequacy
stability and employment objectives.            and the taxation on the roads were some
Future coffee market would be much more         of the problems experienced in handling
efficient if a variable export tax were to be   coffee for farmers (237140, 237196,
introduced to compensate for differences        237249, 237157, 237291). The Kenya
between the world market and domestic           Planters Cooperative Union Ltd (KPCU)
                             Economics of coffee production   32

provides milling, grading and sorting
facilities with the objective of enhancing
quality and maximising farmers returns
(237253, 237344, 237417, 237418,
237425, 243570, 244084, 237220).

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