Impacts of P inputs on availability of Fe, Mn, Zn and Se in soils

Document Type : Original Article


1 Soisl and Water department, Faculty of Agriculture, Benha University

2 Soils and Water department, Faculty of Agriculture, Benha University

3 Soils and Water Department, Faculty of Agric., Benha University

4 Soils and Water department, faculty of Agriculture, Benha University, Egypt

5 Soils and Water Department, Faculty of Agriculture, Benha University


PHOSPHATE IONS are hard-Lewis-bases, , which might not preferably bind with Fe, Mn and Zn (borderline Lewis acids); though P-applications diminish considerably availability of micronutrients and other elements such as selenium. Interactions between P and these elements are still in need for more detailed investigations. Therefore, the current study was executed as a trial to through more light on such mutual relations. A pot experiment was, therefore, conducted following a complete randomized-design to attain this aim. Briefly, the soils under study (a clayey non-calcareous soil and a sandy calcareous one) were enriched with 5 mg Fe, 1 mg Mn, 1.5 mg Zn and 10 mg Se kg-1 .Thereafter, they received elevated P -doses (15, 30, 60 and120 mg P kg-1) and incubated for 72 h while keeping soil moisture gravimetrically at field capacity throughout this study. Key results revealed that AB-DTPA-extractable-P increased significantly with increasing the rate of applied-P and such increases were noticeable with ageing. In contrast, AB-DTPA-Fe content was not affected significantly by P-applications. Regarding AB-DTPA-extractable-Mn and Zn, their contents increased progressively in the non-calcareous soil upon application of P at 60 mg P kg-1 soil (P60) or the higher for an incubation period extended up to 48h while remained statistically unchangeable in the non-calcareous soil. In both soils, the dose of applied-P did not significantly affect AB-DTPA-Se, yet this available fraction was affected by soil ageing showing fluctuations cycles of increases and decreases. More experiments are needed using additional time sequences within the first 48h of P-application