Phytate efficiency as a phosphorus source for wheat varies with soil properties

Abstract

Aims

Phytate, the most abundant organic P compound in soils, cannot be used as a P source by plants without first being hydrolyzed. However, the effect of soil properties on its effect as a P source to plants is not yet well understood. This study aimed to assess the efficiency of phytate as a P source for plants depending on soil properties.

Methods

Eight soils ranging widely in properties were selected and used in an incubation experiment for 100 days with phytate or soluble inorganic P, both at the same rate of 27 and 80 mg P kg⁻¹; after this incubation period, wheat was grown on these soils.

Results

Phytate was as efficient as inorganic P in increasing Olsen P after incubation. This efficiency (i.e. increase in Olsen P to applied P ratio) of phytate decreased with increasing clay and poorly crystalline Fe oxides content in soils. Phytate increased P uptake by plants relative to the non-fertilized control. Phosphorus uptake from phytate and its equivalence with soluble inorganic fertilizer in terms of crop P uptake (MFRV) varied between soils and decreased with increasing clay content. Thus, soil components involved in the sorption of phytate contribute to a decrease in its efficiency as a P source for plants. Phosphorus uptake from phytate and its MFRV increased with increasing phytase activity and Gram + to Gram − bacteria ratios. Thus, the hydrolytic activity and the composition of bacterial communities of soils affects its use as a P source by plants. Therefore, phytate present in organic residues and soils can be a source of P for wheat, whose availability to plants depends on physico-chemical, biochemical, and biological soil properties.