Determination of Phosphate Fertilizer Requirements by Using Adsorption Isotherms Curves and Its Relationship with Growth and Yield of Maize under Gypsiferous Soils Conditions 2-Effect on Yield and Yield Components


Field experiment was conducted at two gypsiferous soils with gypsum content 5% and 15% to study type and level of phosphate fertilizer ( TSP and DAP) in yield and yield components of maize at two system of tillage , minimum tillage system (MT) and conventional (CT) . phosphate fertilizer was added in five levels which was calculated from adsorption isotherm curves at suggested phosphorous concentration (0.00, 0.20, 0.40, 0.60, 0.90 µg p. cm-3) in soil solution. The quantity of phosphate fertilizer at location 5% gypsum was ( 0, 180, 260, 340, 420 kg/ha-1) while at second location 15% gypsum was (0, 280, 360, 420, 520 kg/ha-1). Results of this study showed that addition of phosphate fertilizers significantly increased grain yield and yield components of maize and highest yield was at phosphate fertilizer level (340 and 420 kg/ha-1) in at soil 5% and 15% gypsum respectively, which corresponding to phosphorous concentration of (0.60 µg p. cm-3). The results also showed that the superiority of minimum tillage (MT) on conventional tillage (CT) in grain yield at soil location 5% gypsum while at second soil location 15% gypsum soil there is no differences between system of tillage in grain yield. The increase of the grain yield was mainly due to the number of grain in corncob and secondly to the weight of 100 grains.