Enhancing of rock phosphate solubility and plant availability in clay soil through inoculation of the rock with phosphate solubilizing fungal cultures and the effect of the amendment of soil with inoculated rock phosphate on phaseolus vulgaris plant growt

Abstract

Enhancing phosphate availability for plants stimulates early plant growth and hastens maturity. This study aimed to enhance solubility and plant availability of low soluble rock phosphate in clay soil by inoculation of the rock with phosphate solubilizing soil fungi. A. niger and A. fumigatus that showed the highest solubilizing ability among fungal species isolated from Egyptian soil. Rock phosphate was inoculated with Cultures of A. niger and A. fumigatus at different concentrations, results revealed that the best-solubilized phosphate value (63.5% & 50.9%) for A. Niger and A. fumigatus. Respectively was obtained at 30%w/v rock phosphate concentration and 15 days incubation period at 30ºC. The inoculated rock phosphate was applied as phosphate fertilizer to (common bean) phaseolus vulgaris plant, the amount of total phosphate and plant available phosphate and water soluble phosphate ofsoil were determined. Soil total dissolved salt and pH were measured along the life cycle of phaseolus vulgaris plant and compared to those of native soil, rock phosphate, and super phosphate. It was found that the addition of rock phosphate inoculated with A. niger culture considerably increased soil total phosphate (by 2.5times), plant available phosphate (by 5.25 times) when compared to native soil. Rock phosphate inoculated with culture of A. fumigates increased soil total dissolved salts by 62.307% greater than native soil; it was also found that rock phosphate inoculated with A. niger enhanced the growth of phaseolus vulgaris plant better than rock phosphate inoculated with A. fumigatus culture, native soil, rock phosphate and super phosphate respectively