Cowpea is the second most important grain legume crop in tropical Africa. About 80% world population lives in Africa with Nigeria being the most populous African countries and also the highest producer of cowpea.
Cowpea is an important food for humans and a source of feed, forage, hay and silage for livestock and green manure and cover crops. The dry seeds may be processed into meal or flour which is used in a number of ways. The fresh seeds and immature pods are eaten as vegetable. The young shoots and leaves are eaten as spinach.
Cowpea is also known as southern pea, black-eyed beans, black-eyed pea, China pea and marble peas.
Steps in Cowpea Production
- Site selection
- Variety selection
- Choosing cropping system
- Land preparation
- Planting
- Application of fertilizer
- Weed management
- Pests Control
- Harvesting
- Storage
- Marketing
Site Selection
Cowpea is a warm weather crop that requires 20-35°C for optimum growth. Most cowpea crops are produced under rain-fed farming. The crop is also grown on sois with high water holding capacity (under residual soil moisture or under irrigation when the cold season like wheat are harvested. Cowpea is grown over a wide range of soil types provided drainage is good. But for optimum yields, light sandy loams are preferred.
Right Soil for Cowpea Farming
Cowpea does well under good soil conditions which are loamy or sandy/loam soils.
It is also important to grow cowpea in rotation with cereal crops to provide natural soil enrichment. It is recommended to apply 5-10 tons of Farm Yard Manure in order to improve soil nutrients, texture and structure.
Cowpea Seed Variety Selection
There are good number of cowpea varieties in Nigeria such as SAMPEA-7 (IAR 48), SAMPEA-8 (IT93K-452-1), SAMPEA-9 (IT90K-277-2), and SAMPEA-10 (IT97K-499-35).
Choosing Cropping System
Cowpea are usually intercropped with crops like maize, millet, and sorghum.
In the traditional cereal farming system, cowpea is inter-planted about 6-10 weeks after the cereal are sown.
It is recommended that the cowpea should be relay cropped after the cereals have been weeded and earthen up.
Advantages of This System
The spreading growth of the cowpeasmothers weeds protecting the soil from the impact of heavy rainfall and it’s likely that the cereal derives some nitrogen from the roots nodules of the cowpea especially towards the ends of the growing season.
Similarly, the roots of the cowpea also excrete a substance that stimulates germination of parasitic witch weed (striga); therefore it’s useful as a trap crop.
In rotation systems, cowpea provides disease break in cereal or tuner crops as diseases that commonly attack cereal and tuber crops don’t affect cowpea.
Land Preparation
Land preparation depends on the cropping system you have chosen
If it’s intercropping, no serious land preparation is need d but when grown as a sole crop, good land preparation is required.
Planting Date
Time for sowing depends on the ecology and should be such as to enable the crop to flower close to the end of rainy season so that grains mature in dry weather.
In Nigeria, cowpea is planted in end of June to early July in the Sudan zone, med-July in the northern Guinea Savanna, mid-to late-July in the northern part of Guinea Savanna, and as soon as the late season rain starts in the Southern part of the southern Guinea Savanna and about mid-August in the derived savanna and forest zones.
Planting Methods
Sowing should be done in moist soil at 10-30cm intra-row and 60-90cm inter-row depending on the type of cowpea. Erect types are sown at close spacing than the spreading types.
The seed Rate for spreading types is 10-15kg/ha and 25-30kg/ha for erect varieties.
Sow three seeds per hole and thin three to two plants per stand at 2WAS.
On a land sown with cowpea for the first time, it should be inoculated with a fresh culture of cowpea bacteria for proper root nodulation and nitrogen fixation. Inoculation should be done before sowing.
Cowpea germinates within three days.
Fertilizer Application
Where cowpea is grown in mixture (intercropped), it comes late and the fertilizer applied to the main crop will meet the cowpea requirement.
But when it is sown for the firytime in the field or where the soil is nitrogen deficient, application of starter dose of N at 20kg/ha is necessary.
Cowpea has a high requirement for P particularly towards the end of the growing period. This is because 80% of the total P uptake is absorbed in the last 30 days of growth and is mostly translocated to the seeds.
There is no response of K fertilizer in most savanna soils because of high K-status. However, it has a high K requirement and the general fertilizer recommendation is 20,kgN, 40kgP205/ha
The fertilizer should be applied at sowing but not beyond 2WAS
Harvesting
Cowpea green pods can be harvested to be used as vegetable, and can be harvested for grains.
The duration or maturity for these two different purposes differ.
For green pods to be used as vegetable maturity is between 45 - 90 days after sowing depending on the variety. For grains, the crop matures in about 90-125 days after sowing when pods are fully matured. The harvested pods should be dried to reduce the moisture content of the seeds to 10% for safe storage. Thoroughly dried pods are easily thresh by hand using sticks, or with a conventional thresher. Thresh on mat or tarpaulin to avoid contamination with stones and other foreign objects.