Soil nutrient and sediment loss as affected by erosion barriers and nutrient source in semi-arid Burkina Faso

In semi-arid Sahel, soil erosion by water is one major factor accounting for negative nutrient balances in agricultural systems. A field experiment was conducted on a Ferric Lixisol in Burkina Faso to assess the effects of soil and water conservation barriers (stone rows or grass strips of Andropogon gayanus), the sole use of organic (compost) or mineral (urea) source of nitrogen (N), and the combined use of barriers and compost or urea nitrogen on soil nutrient and sediment erosion. The run-off barriers were put along contours. Organic carbon (OC) and nutrients losses through run-off and sediments were monitored during 2001 and 2002. Carbon and nutrient concentrations of generated sediments were very high, of 14-29 g kg-1 OC, 1.0-3.7 g kg-1 N and 0.32-0.71 g kg-1 total P. concentration in run-off water reached 0.023 g L-1 in stone rows treatments compared to only 0.002 g L-1 with treatments without barriers. Annual losses of organic C, N, P, and K were high and greatly dependant on soil loss magnitude. Compared to the control plots, soil losses were reduced on average by 84% during the 2 years with stone rows treatments, while by 71% with grass strips treatments. Compost application reduced soil loss by 75% in plots without barriers and by 89% in plots with stone rows as compared to control plots. With urea application, soil loss was on average 13% lower than in plots with compost. Integrated water and nutrient management can effectively alleviate soil, carbon, and nutrients losses by water erosion, therefore may contribute to intensifying crop production in Sahelian smallholder farming