Author: S. Foli

Publisher:

Published: 2012

Total Pages: 67

ISBN-13:

Farm characterisations based on constructed farmer typology were conducted in the southern and northern Guinea savannah zones of Nigeria. The research was carried out within the framework of the N2Africa project. N2Africa is a research for development project working in 13 sub-Saharan African countries aiming to improve benefits from cultivating grain legumes through better yielding varieties and enhanced biological nitrogen fixation. Data collection took place in the northern Guinea (Bunkure) and in the southern Guinea (Kachia) savannah zones. The study aimed to understand the role of three grain legumes: cowpea (Vigna unguiculata), groundnut (Arachis hypogaea) and soybean (Glycine max) in the farming systems of the chosen agro-ecological zones and how these legumes can further contribute to improved soil fertility and crop production. Socio-economic data was collected including farm and household sizes, farming objectives of smallholders, livestock, off-farm income or remittances, and labour arrangements. Rainfall data, soil and crop sampling, and biological nitrogen fixation measurements were taken. Major socio-economic differences between the study sites were household sizes, farm size, and livestock densities. The above were all higher in Bunkure than in Kachia. Average annual rainfall ranged between 1392-1797mm in Kachia accompanied by a 195 days growing period. On the contrary, annual rainfall in Bunkure was between 714-841mm per annum with a 135 days growing period. Cropping in Bunkure entails intercropping of cereal and grain legumes. Cowpea is important for food and groundnut is sold for income. Farming in Kachia is oriented towards income generation with ginger being the most important cash crop. Groundnut and soybean are also grown for sale on the market. Maize is the dominant food crop. Analysed soil samples revealed low fertility of soils in Bunkure, well below critical levels of P and K. Low clay content of 11% on average translated into low availability of the important plant nutrients N, P, and K. Average pH on the other hand very satisfactory (6.2), also for Kachia (5.6). Higher clay content of soils (24%) in Kachia showed higher soil fertility in terms of organic carbon, total N, available P, and exchangeable cations. Average plant N derived from biological nitrogen fixation in grain legumes was 74% (84 kg N ha-1) in Bunkure for cowpea and groundnut. In Kachia, this was 44% (44 kg N ha-1) for groundnut and soybean. Large variations in nitrogen fixation occurred between fields but cowpea gained the highest benefits from nitrogen fixation in Bunkure, whilst groundnut gained the least N from biological fixation in Kachia. This study was able to show that grain legumes occupy an important role within farming systems in northern Nigeria mainly through their contribution to food self-sufficiency, farm income, and fodder for livestock. The use of legume fodder to feed livestock in the southern Guinea zone is however much less than in the north and most farmers left their residue on the field after harvest. Other cash crops mainly ginger compete with grain legumes for crop land but soybean and groundnut are still important for income generation in the southern Guinea zone. At both study sites, grain legumes were the most profitable crops on a per hectare basis. The study concluded that, additional benefits from grain legumes in northern Nigeria should come through better management of residue to maintain soil fertility in Kachia where farmers have less need for fodder. At Bunkure, improved handling and storage strategies for farmyard manure are necessary to ensure good quality in nutrient cycling through legume residue that is fed to livestock.