Biomass transfers and nutrient budgets of the agro-pastoral systems in a village territory in south-western Burkina Faso

Privatisation of grazing resources is emerging in the agro-pastoral systems of West Africa, resulting in increased pressure on the remaining communal rangelands and greater competition between farmers for access to crop residues. Differential management strategies arise as determined by household diversity. This study quantified the flows of biomass and related nutrient budgets in relation to farm diversity in Koumbia, a representative village of south-western Burkina Faso. Four farm types were identified: subsistence-oriented and market oriented crop farmers, agro-pastoralists and pastoralists. Crop farmers collected about 30 % of their maize harvest residues for feeding during the dry hot season, while agro-pastoralists and pastoralists stocked about 50 % of their maize residues. Whilst the remaining crop residues on (agro)pastoralist farms were almost entirely grazed by their own cattle, about 90 % of the crop residues of crop farmers were consumed by cattle of (agro)pastoralists. On the other hand, available manure from cattle in the village was mainly used to fertilize the fields of the livestock owners. As a result, the cropped land of farmers with few livestock is continuously mined for nutrients. Calculated partial balances of N and K at farm level were negative for all farm types, except for N in the case of pastoralist farms. N and K balances of cropped fields were generally negative on all farm types. Partial balances of P were generally positive, which was to a large extent due to P fertilizer use. Better integration of crop and livestock production activities on farms and between farms offers a pathway to more efficient nutrient cycling with reduced nutrients losses. (Résumé d'auteur)