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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).
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