Effect of contiunous mineral and organic fertilizer inputs and plowing on groundnut yield and soil fertility in a groundnut-sorghum rotation in Central Burkina Faso

Two field groundnut-sorghum experiments were conducted at Saria in the center of Burkina in order to assess the effect of chemical and organic fertilizers on groundnut yield and its components and soil fertility on two ferruginous tropical soils of different texture. Groundnut haulm yield, pod yield, number of pods, % pod two-seeded, % pod rot, seed yield, and 100-seed weight as well as sorghum dry shoot and grain yields were measured for 8 years. Most of the different variables were affected by continuous cropping without fertilizer application on the two soils, in particular on the coarser one. The effect of a likely deficiency in some nutrients (P, K, and Ca) was observed. The mineral fertilizers allowed maintaining yield, but their supply was not able to replenish the nutrient uptake by plants. The effect of compost on the crop production was weak but enhanced during the years 7 and 8. Tillage had also an effect on yield, but this effect was limited and varied with soil type. In the control, the initial status of organic matter reduced in 5 years and did not increase with the application of fertilizers and compost. In contrast the addition of fertilizers increased the content of total N and Bray-I P. Nitrogen, P, K, and Ca balance was negative in almost all treatments without mineral fertilizers. However, the surplus of production did not provide significant profits. The cultural techniques improved sorghum growth, while groundnut responded better than sorghum on the soil eroded. (Résumé d'auteur