The cowpea is one of the most important grain legumes in Africa. Cowpea is both economically and nutritiously significant. Its ability to fix nitrogen efficiently and grow in a wide range of conditions means that the cowpea is also a suitable companion for a wide range of other food and fiber crops.
Nigeria is the worldâ€™s largest producer of the crop, growing 45% of the global yield. However, this total amount has dropped considerably in the past 30 years, from 61% in 1981 to 45% in 2004. With cowpea playing such a key role in the agriculture and food supply of Nigeria, production and processing practices need to be improved, emphasized Thierno Diallo of IITAâ€™s Postharvest Utilization Unit.
The production and processing begins before the seeds have even been planted. Land clearance involves cutting down trees, pulling up stumps, leveling the land, and extracting roots and stones.
Of all the agricultural operations, land clearance is the most difficult and costly. After this the soil must be properly prepared to create good conditions for the seeds to germinate and grow. This starts with the time- and energy-consuming preparation of the seed bed and includes planting and fertilizing. The plant must then be maintained for its life span. This means preventing weeds, pests, and organisms that cause diseases such as bacteria, fungi, and viruses, from severely affecting the crop, as well as keeping the cowpea irrigated if so required.
When fully mature the plants are ready to be harvested. This involves cutting the dry pods before they are attacked by birds or rodents. After this the pods must be opened to release the grains. This is done in two stages: first, the pods are beaten to open them and then they are scooped up and fanned out to separate the grains from the shells in a process called threshing. The grains are collected and dried to increase quality and shelf life, then stored.
All of these operations are traditionally done by hand or with the help of animals and are thus associated with drudgery. â€œThe mechanization of existing tools and the promotion of efficient farm management techniques could be the way to increase Nigerian cowpea production once again,â€ Diallo said. Diallo had been involved in designing some processing machines now in use by small industries in Nigeria and other sub-Saharan African countries.
The advantages of mechanization have already been demonstrated with threshing. Traditionally, sticks were used to beat the grains out of the pods but they sometimes broke the seeds, rendering them useless. In the 1990s, IITA introduced a tool called the Fail-safe Flail, which prevented most of the damage to seeds. The motorized multicrop thresher further improved the process as it could do the job of several workers with flails, taking away much of the drudgery. These two devices increased the productivity of threshing. The recent introduction of a fanning system to the multicrop thresher has made it significantly better still.
Drying is another area where successful mechanization has been implemented. Farmers used to spread the cowpea grains on the ground to dry under the sun. The introduction of drying platforms has not only made the process more hygienic but also more flexible as it does not depend on the sun any longer. Dryers of various designs and capacities are available, from small drying shelves to medium-capacity cabinet dryers and high-capacity rotary dryers. The larger dryers use fuels such as charcoal, wood, or diesel as the source of heat. Some are equipped with a milling facility to produce flour.
By upgrading to machines such as these a farmer could not only get through the various stages of production faster but also run systems such as irrigation, uninterrupted. This in turn would cut costs and improve overall yields as well as boosting confidence and encouraging more people to grow cowpea.
Furthermore, the high cost of purchasing or renting a machine would be offset by the fact that one machine is now capable of completing many different tasks.
Thus, when it comes to producing and processing cowpea, a move to mechanization is essential to fulfill the demand for the crop in Africa and worldwide, according to Diallo.