General Information and Agronomic Aspects
Coffee is one of the most important cash crops in Kenya. It is grown in large-scale plantations (42,000 ha from 2001-2005) as well as by small-scale holders (128,000 ha) giving a total production of about 50,000 tons annually. The main variety in Kenya is Arabica coffee (C. arabica).
The stimulating effect of the coffee beverage is largely derived from the alkaloid caffeine, but cured beans have to be roasted and finely ground to bring out the characteristic coffee aroma. In some producer countries, roasting of locally available coffee in the home is very common and the brew is prepared by pouring hot water over freshly roasted and ground coffee beans.
An important constituent of the coffee bean is caffeine. The free caffeine content in a bean is dependant on the coffee type, variety, the site conditions and other factors, and can be more than 2.5%.
Economically, the most important coffee varieties are Coffea arabica called "Arabica" and Coffea canephora called "Robusta". The latter yields about 30% more than "Arabica", albeit its price is around 30% lower.
Coffee is mainly grown as a beverage, though the plant residues can provide fuel (coffee charcoal or wood) and a good mulch.
Until now, organic cultivation has been of less importance in such countries as Ethiopia, Kenya and Mozambique. It is mostly organic "Arabica" that is being cultivated. "Robusta" is currently barely available in certified organic quality.
Nutritive value per 100 g of edible portion
|Raw or Cooked Coffee||Food|
(Calories / %Daily Value*)
(g / %DV)
(g / %DV)
(g / %DV)
(g / %DV)
(mg / %DV)
(mg / %DV)
(mg / %DV)
|Vitamin B 6|
|Vitamin B 12|
(mg / %DV)
(mg / %DV)
(g / %DV)
|Coffee brewed from grounded berries||1.0 / 0%||0.0 / 0%||0.0 / 0%||0.1 / 0%||2.0 / 0%||3.0 / 0%||0.0 / 0%||49.0 / 1%||0.0 IU / 0%||0.0 / 0%||0.0 / 0%||0.0 / 0%||0.0 / 1%||0.1 / 4%||0.4|
*Percent Daily Values (DV) are based on a 2000 calorie diet. Your daily values may be higher or lower, depending on your calorie needs.
Climate conditions, soil and water management
The ideal temperature range for Arabica coffee lies between 18 and 24o C. Maximum day temperatures should not exceed 30oC and night temperatures should not fall below 15degC. At higher temperatures, bud formation and growth are stimulated. Low temperature or wide daily temperature variation may result in distortion, yellowing and cracking of the leaves and tip growth, a condition known as "Hot and Cold" or crinkle heat. Arabica coffee is normally grown at altitudes from 1400 to 2000 m (4,500-6,800 ft) with a rainfall of not less than 1000 mm per year. Where coffee is grown under conditions of minimum rainfall, mulching is essential to conserve moisture.
Robusta coffee is more resistant to pest infestation and is well adapted to warm and humid equatorial climates with average temperatures of 22-26degC, minimum not below 10degC at altitudes of 100-800 m, and well-distributed annual rainfall of 2000 mm or more. The ideal amount of rainfall lies between 1500 and 1900 mm. Coffee reacts positively to a drought period, which should nevertheless not be longer than 3 months. The rainfall should be evenly spread throughout the rest of the year. Irregular rainfall causes uneven blossoms and fruit maturity. Coffee is a half-shade plant, which can only utilise around 1% of the sunlight for photosynthesis. At leaf temperatures over 34o C, assimilation is practically zero, meaning that the rate of photosynthesis of a shaded plant is actually higher than that of a plant fully exposed to the sun.
As a rule: Grow in lower regions Robusta and in higher regions Arabica. The borderline is variable, and lies around 1400 m in Kenya. The berry borer and coffee rust are important indicators as to whether the coffee variety is suited to the site conditions. For example, an Arabica plantation at 1200 m, which is heavily infeced with coffee rust and infected by berry borer, despite sufficient shade, is an indication that the variety is ill-suited to the site, and should, in time, be replaced with Robusta.
Coffee prefers well-drained and airy soils. It needs free drainage to a depth of at least 1.5 m and 3 m in drier areas. Humus-rich, lightly acidic soils (pH range 4.4-5.4) are beneficial; the best conditions are those to be found on virgin soils of volcanic origin. The topsoil should contain at least 2% humus.
Propagation and planting
|'Ruiru II'||All coffee growing areas||2 x 2 m |
(6 x 6 ft)
|'SL 34'||High altitude with good rainfall||2.75 x 2.75 m |
(9 x 9 ft)
|'Sl 28'||Medium to high altitude coffee zones without serious leaf rust||2.75 x 2.75 m |
(9 x 9 ft)
|'K7'||Low altitude||2.75 x 2.75 m |
(9 x 9 ft)
Vegetative propagation can be done by rooting of cuttings, grafting, top-working and micro propagation (tissue culture). Major considerations for vegetative propagation are:
Choice of mother trees.
- These trees are derived from seedlings that have undergone a pre-selection test for coffee berry disease and coffee leaf rust resistance.
- Establishment of a clonal garden. The selected mother trees are established in the field as per the recommended spacing of 1m x 1m. After 12-18 months, the primary branches are removed and the stems bent and pegged down in a horizontal position to encourage growth of orthotropic (vertical) shoots.
Construction of a propagator:
- The propagators whose width measures 0.75 m (2.5 ft) are constructed on a 60 cm foundation with a wall that rises another 50 cm above the ground.
- To achieve good drainage, the first 15 cm from the ground level are filled with gravel covered by a layer of sand of about 7.5 cm. Finally a 15 cm rooting medium is placed on top of the sand. Recommended rooting media is either of the following: a) sawdust from cypress trees, b) pure river sand or c) sub-soil, all free from any contamination.
- The propagator should be provided with a watering system (mini sprinklers) with emitters at 150 cm spacing.
- To regulate relative humidity, the propagators are covered with clear polythene sheeting, gauge 1000 suspended 1 m above the rooting medium on steel or wooden frames. Shade is normally erected about 2.75 m (9ft) from the ground. The recommended materials for shade are sisal/bamboo poles, shade net (75% shade) or interwoven nets.
Propagation of rooted cuttings:
- Suckers are harvested from the mother trees when they are 6 months old and bearing 6 internodes. Harvesting is done early in the morning when the atmospheric relative humidity is high.
- Single node cuttings are prepared by making a cut at an angle below the node but retaining the pair of leaves.
- The cuttings are planted in propagators at a depth of 2-4 cm and a spacing of 4 cm x 4 cm. Callus formation begins 3 weeks after planting and is complete in 5-6 weeks. (callus formation is the healing of the cut edge of the cutting in the rooting media).
- Root development follows after 8-10 weeks
- The rooted cuttings are transplanted at 12-14 weeks into black polybags measuring 12.5 x 22.5 cm (5x9 in), 200 gauge filled with rich composite soil mixture consisting of top soil, river sand and well rotted manure at a ratio of 3:2:1 respectively, all free from any contamination. For organic propagation rock phosphate is added and if insects normally pose a problem, incorporate chopped leaves of Lantana camara or Mexican marigold.
- The potted seedlings are returned to the propagators for a period of 1-2 months to develop more foliage and feeder roots under the same environmental conditions.
The planting materials are then taken care of as per the nursery recommendations.
- Grafting: This is the successful healing of the union between the scion and the rootstock. Grafting requires 10-12 month old seedlings (or pencil thick) to be used as rootstock. Rootstocks of the commercially existing Arabica varieties are compatible with 'Ruiru II'. The graft union is tied with a polythene tape and the entire seedling is placed in a propagator to heal.
- Topworking: This is a cheaper method of converting mature old trees of traditional Arabica coffee into 'Ruiru II' without uprooting and replanting. Sucker growth is induced on the trees to be converted by side pruning. Six month old healthy suckers are selected and grafted with single node scions of 'Ruiru II' bearing a pair of leaves. The graft union is tied with polythene tape to keep the scion in place. Advantages of Topworking:
- A farm can be converted from the traditional cultivars ('SL 28', 'SL 34' or 'K7') to 'Ruiru II' without interfering with normal cropping pattern.
- The farmer saves on cost of uprooting old bushes and new establishment costs.
- The well-established root system of old stumps prevents lodging, which may occur when young "Ruiru II" trees carry a heavy crop.
Coffee Nursery Management
Most cultivars of the self-pollinating Arabica coffee are practically pure lines, propagated by seed. In Kenya, F1 hybrid seeds are produced by hand-pollination of new disease-resistant Arabica cultivars, and certified seed can be obtained from the Coffee Research Foundation in Ruiru.
- The nursery site should be selected on level to gently sloping ground. On sloping ground of 4-5 % it should be bench terraced, sheltered from strong winds, near a permanent reliable water source, accessible and free from weeds.
- The bed construction should be 1m (3 ft) wide with a shade 60 cm (2 ft) above the bed.
- Plant only certified disease free seed from the Coffee Research Foundation (CRF). Sow immediately after collection to avoid loss of viability in order to ensure high germination rate. Remove the husks to reduce germination period. 1 kg seed contains an average of 3,000 seeds.
- Germinate in river sand beds of 5-7 cm (2-3 in) depth with a spacing of 2.5 x 2.5 cm (1 in) and 1 cm (1/2 in) deep. Apply a thin mulch cover. Shade 60 cm above the bed. Water adequately (avoid waterlogging)
- .Remove mulch when seeds have germinated.
- Seedlings emerge after 4 weeks and take another 4 weeks before they are transplanted to polybags
- Transplant pre-germs at the leaf stage into polybags. Avoid deep planting. This ensures minimal disturbance to roots during transplanting, and makes long distance transportation more convenient. Also field establishment can wait till the weather is favourable.
- Renew seed bed and river sand every time new seeds are being planted
- Potting mixture: top soil: 3, sand: 2, well rotted manure or compost: 1. To this mixture add phosphorous, for organic farming a handful of rock phosphate to about 6 "debes" (debe = 20 litre bucket) of mixture as well as neem cake or chopped up leaves of Mexican marigold or Lantana camara for insect control.
- Water seedlings at 2 times a week and control weeds by hand weeding. Control diseases (damping off, leaf rust and Brown eye spot ) using 0.5 % Copper solution, and control insect pests when noticed.
- Shading. Put a shed at 120 cm (4 ft) above the polybed, and provide dense shade initially. Harden the seedlings by gradually reducing the shade. Reduce the shade by half when the seedlings are 8-9 months old and completely 1 month beforetransplanting.farmyard manure or well rotted coffee pulp plus 200 g rock phosphate. If the soil is acidic add 100 g dolomitic limestone (CaCO3 MgCO3).
Land cleared of trees within 6 months should not be used for coffee because of the risk of Armillaria , a fungal disease which causes root rot.
Clear land well in advance, digging out all stumps, bushes and grasses such as kikuyu grass and couch grass. If the land has steep slopes, make terraces or other conservation structures. Protect bench terraces by planting grasses e.g. Paspulum notatum on the bench faces. Planting holes should be dug 3 months before the onset of rains to allow weathering.
Fill the holes 4 weeks before planting with a top soil mixed with 1 "debe" (20 litre bucket) farmyard manure or well rotted coffee pulp plus 200 g rock phosphate. If the soil is acidic add 100 g dolomitic limestone (CaCO3 MgCO3).
Dig holes of size 60 cm x 60 cm x 60 cm at a spacing of 2.75m x 2.75m for the traditional varieties ("SL28", "SL34" and "K7"). A closer spacing of 2m x 1 m on flat land for small holders without spray roads is recommended. Spacing for "Ruiru II" is 2 x 2 m or 2 x 1 m giving a population density of 2,500 - 3,300 trees/ha for small holders. Transplant potted seedlings when they are about 30-40 cm high with maturing bark about 15 cm (6 in) and 2-3 pairs of lateral branches at about 12-15 months old.
Mulching has several benefits to coffee e.g. conservation of moisture during dry spells, suppression of weed growth, nutrient supply, improvement of soil structure and water infiltration, checking of soil erosion and top soil temperature as well as reduction of thrips incidence. Mulching also enhances root development in the fertile top soil and thus a general yield increase. Examples of mulching material include napier grass (half an acre of napier grass gives enough mulch for 1 ha (2.5 acres) of coffee land), sisal waste, coffee prunings, maize and banana trash. When using coffee prunings, take care that no pests (leafminers, mealybugs, etc.) are on the prunings otherwise they could re-infest the trees.
Shade trees and windbreaks
Plant shade trees 1 year before coffee transplanting is required. Common shade trees are leucaena (Leucaena leucocephala) and mother of cocoa (Gliricidia sepium). Also Grevillea robusta, Albizia spp and Cordia abyssinica are recommended shade trees. (See also below under Diversification Strategies). With intensive cultivation and optimum inputs, higher yields are obtained with unshaded coffee, but shade will prevent overbearing and shoot dieback under lower standards of crop management or suboptimal ecological conditions.
Coffee grows best with shade trees. Shade trees reduce stress in coffee. Avoid extracting timber at random for short-term gains. Maintain a two-layer canopy consisting of temporary and permanent shade trees like coconut, Ficus species, Albizzia species, jack fruit, and citrus, etc. At higher altitudes temporary shade trees may be phased out once the coffee is well-established. Regulate shade every year instead of once in 3-4 years to minimize damage to coffee bushes. Shade tree selection and management are important because better shade may decrease the incidence of some important pests and diseases. Suppressing of weeds, particularly East African couch grass (Digitaria scalarum) and Kikuyu grass, by careful tillage (not damaging the superficial feeder roots of the coffee), mulching and/or leguminous cover crops, is very important.
Fertiliser requirements depend on crop level and nutrient status of the soil. Nutrients removed by harvesting 6 t of fruits of Robusta coffee, equivalent to 1 t of green beans, are: 35 kg N, 6 kg P2O5, 50 kg K2O, 4 kg CaO, 4 kg MgO, 0.3 kg Fe2O3 and 0.02 kg Mn3O4. Return coffee pulps and hulls as organic fertilizer in coffee fields. These are rich in nutrients. A 60 kg bag of coffee pulps/hulls contains: 1 kg N; 0.60 kg P; .09 kg K and other trace elements.
Mulching using dried banana leaves and cut dried grass conserves soil moisture, protects soil from compaction, and reduces soil acidity.
Pruning is essential in coffee production:
(a) to determine the shape of the tree
(b) to maximise the amount of new wood for the next season's crop (c) to maintain a correct balance between leaf area and crop and
(d) to prevent over-bearing and thus reduce biennial production or death of trees.
Unpruned coffee usually produces a heavy crop one year and a lighter crop the next season. Pruning makes trees more manageable and easier to pick and spray. Diseases and insect pests can also do more damage in unpruned coffee, as they tend to build up in the older branches.
- Suitable crop : leaf ratio
- Uniform yearly cropping
- Good light and air penetration and circulation for better fruiting and bringing vigour to the tree
When to prune:
Immediately after main crop harvesting. Sick-looking trees due to die back to be pruned only after new growth. Trees attacked by star scales to be pruned after the main crop to avoid carrying the scales to other trees.
Multiple stem pruning: The tree normally has 3 stems and the crop is borne on laterals. Each.lateral bears 2 crops and is then pruned. The crop is therefore borne higher up the tree each year. Every 4-6 years a new cycle is started. This is done by selecting 3 new suckers, which will replace the original stems. In multiple stem pruning, 4 basic operations are carried out:
1. Main pruning: Regulating the number and spacing of primary branches.
2. Secondary pruning: Also known as "handling", involves regulating number and spacing of secondary branches.
3. Sucker control: Removal of unwanted growing shoots called "suckers" (remove them with the meristem, otherwise you multiply suckers)
4. Change of cycle: Selection of some "suckers" to grow into new bearing stems.
How to prune:
Please discuss with a CRF (Coffee Research Foundation) field officer or read CRF Technical Circular No 301: Canopy Management in Coffee, as the recommendations differ from different ecological zones.
1 ) Crops of the upperstorey (shade)
They create large amounts of organic material and humus and at the same time protect the coffee tree against too much sun. The alternation in yield can be reduced, and the life-time of the plantation is increased. Shade also has an immense influence on the quality of the coffee, but it also reduces the yield (fewer coffee trees per area unit). Shading trees also reduce weeds: When an optimum density of coffee and shading trees is reached, tilling weeds is hardly necessary anymore. Shading trees protects against soil erosion and improves the micro-climate on the plantation. By choosing the correct varieties and cultivation method for the shading trees, the micro-climate can be influenced at any point in time. This is very important to regulate pests. Fruit trees offer a diversification for the farmer's diet and economic base. Precious woods can provide a long-term increase in value of the site: along with other varieties, they can provide wood for construction and fuel. Shading trees also creates more pleasant working temperatures on the plantation.
No figures can be offered for the optimum shade density, as this depends on the local site conditions and the state of the plantation. A rule of thumb says that the shade should be around 50%. The higher in altitude the coffee plot lies, the less the distances should be between the coffee bushes and start of the shading roof. At the upper growth limits for coffee plants, the shading plants are therefore at around the same height as them. Care should be taken to trim the shading plants synchronously to the coffee blossoming (6-8 weeks before the blossom). Blossom formation can thereby be assisted and synchronised.
2 ) Crops of the middle storey
As with the shading plants, the variation of varieties used for the middle crop should be adapted to the local site conditions. They can be chosen according to the need for fruits and additional products for each individual plantation. Bananas should, if possible, always be integrated as an additional crop. They are well suited to providing temporary shade, and for 'drying out' of the wetter parts of a plantation. Their ability to mobilise potassium reserves in the soil, and to make them available for the coffee treess is very important. A whole diversity of combinations with other fruit trees can be integrated into the system: citrus planted together with avocado, are especially good for sites that enjoy intensive sunlight.
3 ) Crops of the under storey
On sites which are not optimal (e.g. too dry or poor in nutrients), it makes sense to replace the natural vegetation in the under storey with green manuring plants (legumes). The bottom crops should never be allowed to dominate and completely displace the natural vegetation. Many varieties are suitable as bottom crops. They should be selected according to the amount of shade they provide, soil conditions and rainfall. In principle, bottom crops should be sown on new plantations, or when the shading trees and coffee bushes are being trimmed. Otherwise there will not be enough light on an organic coffee plantation for the bottom crops. It is very important to sow perennial, non-climbing and not very aggressively growing legumes. Otherwise there is a danger of the coffee plantation becoming overgrown e.g. with tropical kudzu (Pueraria phaseoloides).
Each year coffee is harvested during the dry season when the coffee cherries are bright red, glossy, and firm. To maximise the amount of ripe coffee harvested it is necessary to selectively pick the ripe beans from the tree by hand and leave behind unripe, green beans to be harvested at a later time. Selective picking of coffee berries at 10-14-day intervals is common where harvesting extends over a period of 7-9 months. Where the harvesting season is shorter, whole branches are stripped when the majority of berries are ripe. Costs of harvesting will be 2-3 times higher for selective picking than strip picking. Deliver berries for processing the same day they are picked.
Pulping must be done on the day coffee is picked as coffee left in the sun will start to ferment. Pulping is done to remove exocarp and mesocarp through the wet processing method after which coffee parchment is obtained. The parchment is then dried in shallow layers on raised tables or trays to moisture content of 10-11%. For more information on processing, please contact Coffee Research Foundation (CRF), Ruiru.
Stinkers are a severe form of over fermented beans. These defective beans will give a bad (unclean, over fermented, pulpy, sour, foul) taste to brewed coffee and will down grade the delivered coffee, causing loss of considerable earnings. Long fermentation times (more than 4 days) and hot temperatures are the main culprits producing these unpleasant beans.
Coffee stores should be dry, clean and well ventilated. Never store or keep chemicals in a coffee store. Keep fully dry coffee beans on wooden tables or floors or even in ventilated bins. They should be stirred or turned every day for 10 days before bagging. They must be put in sacks as they come from the drying tables. Place bags on wooden battens 15 cm above the ground or concrete floor and away from walls. Do not store close to corrugated iron sheets. Store for a minimum of 4 weeks and a maximum of 6 months. After that beans become woody. A relative humidity in the store of 60% at 20degC is suitable.