Cover crops are planted to conserve the soil on bare, fallow farmland or under a main crop. They can be grown on their own or between rows of annual and perennial crops such as maize, coffee, and fruits. The main purposes of growing cover crops are to cover the soil with low-growing vegetation, protect the soil from exposure to sun and rain, suppress weeds, improve soil fertility, supply livestock feed, and manage insect pests. Cover crops may be nitrogen fixing (if legumes), and they make productive use of spaces between crop rows, as well as controlling wind and water erosion. They also have the potential to restore soil fertility and help in climate change adaptation, as well as sequestration of atmospheric carbon above and below soil surface. Furthermore, cover crops can be fed to livestock, helping to bridge periods of shortage of feed when grazing lands are not available – which is an increasing problem because of growing population pressure and expansion of croplands. Land users give huge credit for its role as a pesticide by deterring armyworm and stalk borer when used as a border, and stopping their advance into the maize crop.
Desmodium is an example of a leguminous cover crop, improving soil fertility via fixing atmospheric nitrogen, increasing infiltration and productive use of soil moisture, and catering for livestock via a “cut-and-carry” fodder system. Desmodium is planted between rows of maize crops as well as between grass hedgerows around the farm. For its establishment, access to desmodium seed is essential. Once established, it remains to serve as a permanent source of planting material. Nevertheless, there are some disadvantages of desmodium: seed collection is difficult, it may trap honey bees and it can compete with the crop for light and space if allowed to grow too tall. Thus, efficient management of desmodium is essential. Nevertheless, as part of an agro-ecological intervention, cover crops like desmodium deliver multiple benefits to resource-poor farmers and can be viewed as an investment in improving soil fertility as well as soil health. Overall, cover crops improve productivity, and help ensure yield stability and contribute to a healthier ecosystem.
