According to a recently released ‘Cowpea Livestock Feed’ factsheet by the International Livestock Research Institute (ILRI), cowpea is a dual-purpose, fast-growing, annual legume suitable for grazing, hay/silage, grain, or green manure.
It is an excellent crop for fattening both sheep and cattle and is also regarded as good feed for milking cows. The seeds, pods, and succulent leaves can be consumed as food.
In a crop rotation program, cowpeas can significantly improve soil nitrogen levels by nitrogen fixation or by incorporation in the soil as a green manure crop.
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Forage production
Cowpea produces biomass of about 3–10 t/ha dry matter in 8–12 weeks as crop residue at grain harvest.
Feed quality
Cowpea has a high nutritive value. Crude protein is 6–8 per cent in the crop residue, 14–21 per cent in green foliage, and 18–26 per cent in grain. The dry matter digestibility (IVDMD) of foliage is greater than 80 per cent and of residues after grain harvest is 55–65 per cent.
Strengths
- Multi-purpose legume.
- Easy to establish.
- High nutritive value.
- High palatability.
- Adapted to a wide range of soils.
- Drought-tolerant.
- High yields in a short period
Limitations
- Must have well-drained soil.
- Susceptible to several pests and diseases.
- Sensitive to cold, heavy rainfall, and frost.
- Heavy grazing should be avoided.
Field Management
Field preparation: The field should be well drained and ploughed.
Establishment: Sow 10–15 kg/ha of good quality seed under dryland conditions and 20– 25 kg/ha in irrigated and higher rainfall areas. Cowpea is best sown 1–5 cm deep with good seed-soil contact into a well-prepared seedbed. Plant 2–3 seeds per hill and thin to one plant after seedling establishment.
Cowpea can be grown as an intercrop/mixture with forage sorghum, pearl millet, or maize.
Fertilizer: Cowpea is commonly grown without fertilizer applications but, when grown in less fertile soil, it may benefit from a one-time 100 kg per hectare application of diammonium phosphate (DAP) during planting to help root development.
Weeding: Hand weeding should be done twice within the first five weeks of growth.
Major pests and diseases: Cowpea is very susceptible to insect damage. The legume pod
borer, Maruca vitrata, is the main preharvest pest of cowpeas. Other important
pests include pod-sucking bugs, thrips, and the postharvest cowpea weevil, Callosobruchus maculatus.
Common diseases that infest cowpea plants include blights, root rot, wilt, powdery mildew, root knot, rust, and leaf spot. The plant is also susceptible to mosaic viruses. To reduce disease occurrence, it is recommended to treat the seeds with seed dressing chemicals such as carbendazim or Apron star 42WS.
Harvesting: The ideal time to cut a cowpea crop for hay is at peak flowering, or about 7–8 weeks after sowing. Collect crop residue at mature grain stage i.e. after about 8–12 weeks.
When seasons are suitable, the best forage types will regrow after grazing, but grazing should be light to ensure that the plant frame is retained and damage is limited.
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Environmental adaptation
Cowpea is moderately drought-tolerant and fast-growing in areas with average annual rainfall as low as 500 mm.
It is best grown in areas with annual rainfall between 750 and 1,100 mm.
It’s adapted to produce in a wide range of soils from sands to heavy, well-drained clays, cowpea has a preference for lighter soils that favour good root development. It is commonly grown in heavy textured, strongly alkaline soils.
Cowpea does not tolerate extended flooding or salinity. It is tolerant to heat, but not to frost.