Variation of carbon and major nutrients contents in two types of soil under stone bunds management in cotton-based cropping systems in the Sudanese zone of Burkina Faso

In Burkina Faso, soil fertility decline is a major constraint in cotton-based farming systems. In this area, most of the soil fertility management are mainly focus on soil amendment with organic manure and the used of mineral fertilizers. In addition to these techniques, the present study on the use of stones bunds was conducted at Gombélédougou in order to limit erosion and improve availability of fertilizers provided to plants. Gombélédougou is in the district of Koumbia in Sudanese zone of Burkina Faso. About 605ha covering six (6) soil types were managed using stone bunds established along the contour lines. The spacing between the stone rows was 2.5 m. Concerning additional soil fertility management, it consisted in crops rotation (cotton//cereals); the application of mineral fertilizer at the dose of(110 ± 25 kg/ha for NPK (14-23-15) and 52.5 ± 15 kg / ha for urea (46%)) and organic manure (1787.50 ± 1390.96 kg / ha). The indicators for assessment of the effects of the stone bunds were evaluated using the variation of the carbon and of the major elements (nitrogen, phosphorus, potassium) contained in soil as well as the overall evolution of the fertility of these soils. The results showed that the stone bunds in combination with current fertilization techniques increased the soil carbon level by 0.04% and 0.15%, respectively in Lixisols (FLIP) and Cambisols(BEF) in one hand, and in the other hand, Nitrogen contents decreased from -0.01 to -0.02% and those in Phosphorus from -1.21 to -2.61 mg/kg in these soils. The stone bunds reduced significantly the transfer of sediments and nutrients from upper to the down slopes. As consequences soil fertility was improved in thelixisols located at the up slops at the detriment of Cambisolin the down slop. These results show that the stone bunds are more effective when producers combine an appropriate technique of organic (compost) and mineral fertilization.