Pigeon peas grow in a variety of agro-ecological zones and are well adapted to semi-arid climate conditions.
In sub-Saharan Africa it is widely grown in Kenya, Uganda, Tanzania, Malawi and Mozambique for subsistence, domestic and international markets.
As drought become common and dry lands expand due to climate change, pigeon peas will continue becoming important for managing food security and nutritional situation in Africa.
Unlike other legumes, pigeon peas is one of the few crop species that can utilise iron bound efficiently making it capable of producing appreciable yields even under soil PH limiting conditions which are widespread in Sub Sahara Africa.
Pigeon peas are perennial shrub that is commonly grown as an annual crop. It has very slow initial development after planting. With a deep taproot, pigeon peas are able to take up nutrients and water from lower subsoil layers.
Therefore, in crop mixes they hardly compete with the companion crops. This crop grows and yields well under conditions of low rainfall and poor soil.
The crop has many other uses where the stem is used as fuel, and the leaves and husks provide livestock feed.
Against this background, Emma Mbeyagala, the officer in-charge of breeding the crop at the National Semi Arid Resources Research Institute (NaSARRI), gives excerpts of good agronomy practices farmers can embrace to get good yield.
Soil and water management
Optimum temperatures for pigeon pea cultivation range from 18 to 38 degrees Celsius. Pigeon pea does not tolerate water logged soil and fertility need to be adequate.
Rainfall optimum is approximately 600-1000 mm per year. It is sensitive to high salinity and to water logging. It flowers well where rainfall is 1,500 to 2,000 mm. On deep, well-structured soil, pigeon peas require rainfall of 250 to 370 mm to mature.
Drained soils of reasonable water-holding capacity and with pH 5-7 are favourable for growth.
The commonly grown varieties in Uganda include Apio Elina (green) with maturity rate of six to nine months which gives grain yield of 250 to 500 kilogrammes per hectare.
Adyang variety (white) which matures between six and nine months with the yield of between 250 and 450 kilogrammes per hectare.
Others are ICPL 87101 which matures in 93 - 102 days with yield capacity of 2.2 tonnes per hectare and it is brown grain colour. ICPL 90029 varieties mature in 92 - 104 days with yield rate of 1.6 - 2.5 tonnes per hectare and it is brown.
The newly released varieties include Sepi I which mature in 130 – 150 days with yield rate of 1,200 kilogramme per hectare and Sepi II which yields in 120 days at a yield rate of 1000 kilogrammes per hectare. Propagation is by seed as stem cuttings rarely succeed. Pigeon pea varieties differ not only in form of seeds, colour and taste, but also in growth habit, time of flowering and susceptibility towards pests and diseases. The seed rate is between 20 and 25 kilogrammes per hectare.
Pigeon peas thrive best in seedbeds prepared by deep ploughing and cultivations to reduce weeds.
Seeds should be sown in rows with spacing of 75cm by 25 cm. In dry areas and especially in coarse-textured, infertile soils, farmers use wide spacing between plants to limit competition. Plants are fairly slow to start and weed control for the first two months is important in crop establishment. Once plants are established they grow vigorously.
Weeds must be controlled to facilitate slow initial growth. Wind may bend the plants but staking is not practiced. It is important to weed the farm two to three times during the first two months from planting.
In East Africa, the crop is cultivated on marginal lands by resource-poor farmers, who traditionally grow landraces. Inputs such as fertilisers, irrigation and pesticides are hardly used.
In intercropping, the crop performs well with two rows of cereals such as sorghum, millets including cotton or groundnut.
After harvest of the intercrop, long-duration pigeon peas continue to grow and protect the soil.
It is regarded as a good plant for restoration of fertility and is used in a rotation with crops such as maize-groundnut and tobacco.
One of the advantages of pigeon pea is the increased growth of the grass inter-planted with it.
Farmers usually sow it in alternate rows with sesame or African finger millet and sometimes maize.
The crop is usually cut near the ground when most pods are mature, or mature pods are picked individually.
Green pods are picked over a long period in home gardens or hedge crops.
After harvest the stems are cut back to facilitate re-growth and a second crop is harvested in the subsequent season.
Entire air-dried plants or pods are threshed, usually by hand and seed is cleaned. Clean bins prevent insect attack which can be considerable.
Threshing should be done on clean ground and bags for storage must be new. If possible triple air bags can be used to avoid weevil penetration.
In case of weevil infiltration farmers are advised to use pesticides such as actellic and insecticide dust.
Surveys in Uganda have shown that the most common pests of pigeon pea pods and seeds in the region are pod sucking bugs and seed boring caterpillars and pod flies.
Others are root rot nematodes which cause eventually wilting of the crop.
The most characteristic symptom is formation of root knots and these can be seen with the naked eye. Farmers are advised to plant resistant varieties and plant in fields with no previous record of nematode infestation as well as rotate with cereals.
The common diseases are Fusarium wilt which may cause wilting at flowering stage and crop rotation is advisable and planting of resistant varieties. Another disease is cercoospora leaf spot which causes narcotic sports of the leaf making poding and flowering to abort.
Another is powdery mildew which causes fungal growth affecting all parts of the plant.
The solution is to plant clean seeds and follow the right agronomy practices.