On-farm study of leaf area development and soil moisture variability in pearl millet cultivated in the Sahel. A minor field study

absorption d'eau bilan hydrique du sol contenido de agua en el suelo crecimiento croissance cultivos de grano disponibilidad de nutrientes grain crops growth leaf area niger nutrient availability pennisetum typhoides sahel semiarid zones soil water balance soil water content superficie foliar surface foliaire teneur en eau du sol water uptake