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Review of Kenyan
Agricultural Research
Vol. 24
Coffee Agronomy
by
A M Mailu
ii
Contents
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
iii
iv
Preface
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
researchers.
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‟
farmers.
CG Nderitu
Director, KARI
Nairobi
Kenya
January 1996
v
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
vi
Acknowledgements
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
vii
Notes
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
follows:
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
viii
Agronomy
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,
245708).
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
32
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
(16007).
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).
