Rotation and tillage effects on yield of pearl millet (Pennisetum glaucum) and cowpea (Vigna unguiculata), and aspects of crop water balance and soil fertility in semi-arid tropical environment

alomado aradura bilan hydrique billonnage cero-labranza conservation de l'eau cultivation cultivo fertilidad del suelo labour pennisetum typhoides ph ploughing pratique culturale ridging soil fertility uso del agua utilisation de l'eau vigna unguiculata water balance water conservation water use zero tillage