SOIL PREPARATION
The land must not be waterlogged but well drained. During land preparation, the existing fallow weeds, trees and shrubs in the site are cut down manually, or slashed with a tractor and fallen trees should be removed. This should be followed by plowing and harrowing, using a disc plough and harrow. Some 4 to 6 days between each operation should be allowed to enhance good soil tilth for good seed germination. The land may be ridged or left as flat seedbeds after harrowing.

FIELD LAYOUT AND DESIGN
Both inter-row and intra-row spacing will be determined by the type of variety and growing pattern. More space between plant and rows will be required with trailing types relative to the upright growing pattern. Generally for grain production, a plant population of 200 000 to 300 000/ha at 30 to 50 cm inter-row spacing is preferred to wider rows (70 to 100 cm), which could be suitable to the trailing types.
PLANTING
For optimum yield, cowpeas should be planted late November to early December in lower rainfall areas of South Africa. The seed should be planted at 3 to 4 cm deep. The early-sown crops tend to have elongated internodes, are less erect, more vegetative and lower yielding than those sown at the optimum time. Date of planting manipulation is utilised by farmers for various reasons. The reasons include escape from periods of high pest load or to plant cowpea at such a time that harvesting of the crop would coincide with the period of dry weather.
Plot layout
The field is marked into blocks of known areas with alleyways between blocks to enhance movement of materials and agronomic operations.

Cowpea is a food and animal feed crop grown in the semi-arid tropics covering Africa, Asia, Europe, United States and Central and South America. It originated and was domesticated in Southern Africa and was later moved to East and West Africa and Asia.

The grains contain 25% protein, and several vitamins and minerals. The plant tolerates drought, performs well in a wide variety of soils, and being a legume replenishes low fertility soils when the roots are left to decay. It is grown mainly by small-scale farmers in developing regions where it is often cultivated with other crops as it tolerates shade. It also grows and covers the ground quickly, preventing erosion.

The name “cowpea” probably derives from when it was an important livestock feed for cows in the United States.

FERTILISATION
Fertiliser application in cowpea production depends on anticipated yield and soil fertility. As a legume, cowpea fixes its own nitrogen, and does not need nitrogen fertiliser. Seed should be inoculated with the appropriate Rhizobium species for optimum nitrogen fixation, however nodules will generally form on cowpeas. Application of a phosphate fertiliser is usually beneficial. Cowpea can grow in a pH range of 5,6 to 6,5.
IRRIGATION
Cowpeas are usually grown under dryland rather than irrigated conditions.

WEED CONTROL
Annual grasses and some broadleaf weeds can be controlled by a presowing application of herbicide.
Row crop cultivation may be necessary with cowpeas, depending on the weed pressure, soil conditions, and rainfall. Preplant tillage can assist greatly in reducing early weed pressure, and the use of cover crops.
Striga gesnerioides and Alectra spp. are the principal parasitic weeds attacking cowpeas, particularly in the semiarid regions. The following three are the most common Striga species that are a pest to cowpea: S. hermonthica, S. asiatica and S. gesnerioides.
The pest status is complex because the forms of parasitic weeds that are found on one species cannot germinate on another host plant. Careful observations and records are therefore necessary to clarify which crops are parasitised by which species.

Importance
Cowpea’s high protein content, its adaptability to different types of soil and intercropping systems, its resistance to drought, and its ability to improve soil fertility and prevent erosion makes it an important economic crop in many developing regions. The sale of the stems and leaves as animal feed during the dry season also provides a vital income for farmers.

Production
More than 5.4 million tons of dried cowpeas are produced worldwide, with Africa producing nearly 5.2 million. Nigeria, the largest producer and consumer, accounts for 61% of production in Africa and 58% worldwide. Africa exports and imports negligible amounts.


Harvesting
More than 11 million hectares are harvested worldwide, 97% of which is in Africa. Nigeria harvests 4.5 million hectares annually. The crop can be harvested in three stages: while the pods are young and green, mature and green, and dry.

http://agrobase.com.ng/plantation-of-cowpea/