Influence of Microvariability in Sandy Sahelian Soils on Millet Growth

Abstract

Abstract Microvariability is assumed to be a constraint on crop production in the Sahel zone. Causes and development of microvariability were studied for millet ( Pennisetum glaucum [L.]) on sandy soils. A descriptive model for the development of soil and millet growth microvariability is presented. The investigations (C t , N t , P t , NO 3 ‐, P Bray 1 , soil respiration, crop‐growth parameters) on two differently managed fields (fallow/crop rotation, continous cropping) at the ICRISAT Sahelian Centre, Sadoré, Niger, show that mainly biological factors (pre‐clearing vegetation, termites) lead to soil microvariability. The organic matter cycle, especially the mineralized nitrate at the beginning of the rainy season, is decisive for the development of crop microvariability in an early stage. Water balance simulation demonstrates that the grain yield can be influenced later, especially during flowering, by water stress.