Coffee
Introduction
Coffea arabica & Coffea canephora
Coffee sustains over 100 million people globally and is rated among the largest export
commodities in the world. Coffea arabica (arabica or highland coffee) and Coffea canephora
(Robusta or lowland coffee) are the main coffee species that are commercially grown, however there are 124 coffee species existing and which have been named to date. Coffee Arabica contributes 70% of produced coffee while Robusta contributes 30% (ICO, 2016).
In Kenya, coffee was first planted in 1893 at Bura in Taita hills thereafter it was grown in Kibwezi in 1900 followed by Kiambu in 1904, since then coffee growing was expanded to several areas of Central Kenya, Meru, Kisii, Machakos, Mount Elgon and Rift Valley.
Climatic requirements
Temperature
The ideal temperature range for Arabica coffee lies between 18 and 24oc.
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 deformation, yellowing and cracking of the leaves and tip growth.
Arabica coffee is normally grown at altitudes from 1400 to 2000 m (4,500-6,800 ft).
Rainfall Requirements.
Rainfall of not less than 1000 mm per year is required.Where coffee is grown under conditions of minimum rainfall, mulching is essential to conserve moisture.
Soil requirements
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.
- Prepare the land well in advance, digging out all tree stumps, roots, bushes and grasses.
- Land cleared of trees within 6 months should not be used for coffee planting because of the risk of Armillaria, a fungal disease that causes root rot.
- Ensure soil analysis is done to determine the inherent soil condition.
- Make terraces or other soil conservation structures where the land has steep slopes.
- Protect bench terraces by planting grasses e.g. Blue grass (Paspulum notatum) on the bench faces
- Gradually reduce shade and the watering frequency to harden the seedlings at 7-8 months after potting.
- Completely remove the shade one month before planting.
- Ideally, seedlings are ready for transplanting when they have 1-2 pairs of primary branches.
- This is around 8-10 months after potting.
Batian
- Grown in all coffee growing areas.
- Tolerant to CBD and CLR
Early maturing (18 months). - Cost effective reduces costs by 30%.
Ruiru II
- Grown in all coffee growing areas.
- Hybrid variety.
- Resistant to CBD and CLR.
- Early maturing (18 months).
Cost effective - reduces costs
by 30%. - Compact growth amenable to high density planting.
SL 34
- Grown in high altitude areas with good rainfall .
- Susceptible to Coffee Leaf Rust and Coffee Berry Disease.
SL 28
- Grown in medium to high altitude coffee zones less prone to Leaf Rust.
- Susceptible to Coffee Leaf Rust and Coffee Berry Disease.
K7
- Grown in Low altitude areas.
- Tolerant to Coffee Leaf Rust.
- Tolerant to drought.
Preparation of planting holes
- Layout and peg the planting points along the contours at the appropriate spacing.
- Space holes at 2.74m x 2.74m (9ft × 9ft) for SL 34, SL 28 and K7; 2m × 2m (6.6 ft x 6.6ft) for Ruiru 11 and 2.1m x2.5m (7ft x 8 ft) for Batian variety.
- Dig the planting holes during the dry season, at least three months before planting and onset of rains.
- Planting holes should measure 60cm x 60cm x 60cm (2ft × 2ft × 2ft).
- Place topsoil (first 15cm or 6 inches) and sub-soil (15cm-60cm or 6”-24”) separately.
- 1 month before planting fill the holes with the top soil mixed with a minimum of 1 "debe"(20 litre bucket) of well de composed manure or well-rotten coffee pulp, 100g TSP or 200g SSP.
- If the soil pH is below 4.4, add 100g of lime to the mixture, otherwise add as per soil test results.
- Slightly mound the mixture in the holes to allow for settling.
- Place pegs at the centre of the holes and align appropriately.
Field planting
- Obtain coffee seedlings from KALRO – Coffee Research Institute or any licensed coffee nursery.
- Select seedlings that are about 30 - 40 cm tall, with 1 - 2 pairs of primary branches and that should have undergone sufficient hardening.
- Plant the seedlings at the start of the main rain season after the soil has become wet upto about 60cm (2ft) deep.
- Remove the pot carefully to avoid disturbing the root system.
- Open the soil mound sufficiently at the top centre to accommodate the taproot and other roots and plant the seedling without burying the stem crown.
- Fill in the soil, press firmly without compacting, and avoid stepping on it.
- Avoid deep planting as this usually interferes with nutrient uptake leading to stunted growth.
- During dry spells, water the seedlings at least two times a week until they are well established.
- Avoid over-watering to encourage proper root development.
- Do hand weeding around the young trees.
- Use implements like the half-moon jembe to weed in between the rows.
- In the event that there are stubborn weeds like couch grass, cover the seedlings (with a bucket or bag) before spraying the weeds with a suitable herbicide.
- Apply 50g of CAN per seedling six months after planting.
- After one year, apply 80g of NPK e.g. 17:17:17 per tree.
- One and half year apply 100g of CAN.
- At two years, apply NPK at 125g per tree.
- Subsequent applications should be as per the recommendations.
- For the first two years, abort the flowers to encourage vegetative growth.
- Mulching
Young coffee requires mulching in order to conserve moisture, suppress weeds and moderate soil temperatures. - Apply the mulch around the stem and ensure that it does not come into contact with it to avoid incidences of insect pest attack.
Pruning
- Pruning is a process through which undesired branches are removed in order to concentrate growth on the wanted branches and it is normally carried out after the main harvesting.
- Unhealthy trees due to die-back should be pruned only after new vegetative growth.
Intercropping
- Intercropping can be undertaken within the first two years after establishment.
- Suitable intercrops include short leguminous crops such as beans, tomatoes and Irish potatoes.
- Plant the intercrops using a recommended fertilizer preferably NPK fertilizer such as 17:17:17.
- Plant the intercrop at the middle of the inter rows at least 2 feet away from the coffee rows/stem.
