Vol. 11, Special Issue 7 (2022)

Author(s):
S Balo, A Debnath and A Sen

Abstract:
Inositol hexaphosphate or phytic acid is an important component of soil organic Phosphorous (P). The behaviour of phytic acid or phytate in soil was studied in terms of its adsorption desorption. This was compared with its sorption in goethite and nutrient free sand. To test the availability of P of phytate, Bengal gram was grown in pots using soil and sand as media of growth. Plants were applied with various amounts of phytate and /or inorganic soluble sources of P, compared dry matter weight and P uptake in crop as affected by media of growth and source of P. Phytate sorption was higher in the soil of Jhargram than Chuapara Tea Garden, being two soils used in this study. This was caused as a result of prior enrichment of soil with inorganic and organic P in Chuapara. Similarly, goethite adsorbed much higher amount of phytate, similar to soils, than that of sand. In terms of desorption of the sorbedphytate the soils and the goethite were similar in trend showing considerable hysteresis thereby high buffering capacity. Sand had no or very insignificant site for phytate sorption could not retain phytate during desorption so, exhibiting little hysteresis. The dry-matter weight and P uptake of Bengal gram was noted highest with 100 mg P kg^-1 applied in inorganic soluble form in the soil. This was followed by addition of phytate P in sand at corresponding rate of application of P. At lower rates of P (25 mg kg^-1) inorganic and organic P applied in sand resulted higher dry matter weight and P uptake than the values in soil. This revealed that phytate P could be utilized by plants provided that it remains free in solution. The finding from the present study suggest that organic P in the form phytate is a good source of P and sometimes better than the inorganic soluble forms. Phytate is strongly adsorbed on to the binding sites of soil particles rendering it unavailable in soil solution and thereby hydrolysis by the enzymes of microbial or plant root origin. Further research should be aimed at finding ways and means to hydrolyse P of phytate that is adsorbed on to soil components.