ASSESSING THE ROLE SOME SOIL AMENDMENTS ON PHOSPHORUS AVAILABILITY UNDER CALCAREOUS SOIL CONDITIONS

Laboratory and pot experiments were conducted at Soils Dept., Fac. of Agric., MansouraUniv. during seasons of 2008 and 2009 to investigate the effect of some soil amendments on phosphorus availability, plant growth and nutritional status of faba bean and sorghum under calcareous soil conditions. The used experimental design was split plot design with three replicates. Compost, poultry manure and humic acid were arranged in main treatments at rates of 40, 10 Mg Fed-1 and 50 Kg Fed-1, respectively. However, subtreatments were presented mineral amendments i.e. control, bentonite, vermiculite and sulfure at rates of 0, 10, 10 and 100 Kg Fed-1, respectively. The obtained results indicated that soil addition of humic acid was superior for increasing the mean values of available P followed by poultry manure and finally the treatment of compost. Regarding the effect of soil mineral amendments, using of sulfur was more effective than other additives on increasing the mean values of available P under different forms of organic manure. The positive effect of humic acid on increasing available P in soil was reflected in increasing vegetative growth parameters and nutrients concentration in faba bean and sorghum plants. On the other hand, the mineral application of sulfur was more efficient than other mineral additives (bentonite and vermiculite) on stimulating vegetative growth parameters and increasing nutrients concentration in plant.