Determination of Phosphate Fertilizer Requirements by Using Adsorption Isotherms Curves and Its Relationship With Growth and Yield of Maize Under Gypsiferous Soils Conditions 1. Effect in Vegetative Growth


The stud aim to determination the phosphate fertilizers requirements for corn under condition of two gypsiferous soil using adsorption isotherm curves which correspond phosphorus concentration (0.00 0.20, 0.40, 0.60, 0.90 µg p. cm-3) in soil solution. Field experiment was conducted at two gypsiferous soils with gypsum content (5% and 15%) the study included two system tillage minimum tillage and conventional tillage and two types of phosphate fertilizers TSP and DAP. , five levels of phosphorous fertilizers were; 0, 180, 260, 340, 420 kg/ha-1 for soil with 5% gypsum and 0, 280, 360, 420, 520 kg/ha-1 for soil 15% gypsum These amounts equal to the suggested phosphorous levels of soil solution. Results indicated that addition of phosphate fertilizers significantly increased the dry matter yield and The highest dry matter yield was with level of 420, kg/ha-1 in the two gypsiferous soils. The highest value conc and uptake of N, P,K was with 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 showed that the minimum tillage (MT) was higher than conventional tillage (CT) in dry matter yield and conc. Of N,P,K at soil 5% gypsum while there was no effect in general at soil 15% gypsum.