Zinc-Phosphate Interaction in Maize

High phosphate application/availability was observed to induce zinc deficiency. The present investigation was taken up to study the possible mechanism of P-induced zinc deficiency in hybrid maize. Ganga-5 was the test crop. The investigation was carried out in two soils, Regur (black soil) and Chalka (light soil), typical of Telengana region of Andhra Pradesh. Phosphate induced zinc deficiency was observed only in the black soil receiving more than 120 kg Olsen extractable P₂O₅. The P-induced zinc deficiency was noticed when the tissue P was 0.38 percent and above and when the P/Zn ratio was greater than 280. Thus the mechanism appears to be more physiological. The recovery of zinc through uptake and ammonium acetate dithizone extraction of soil was not affected due to increase in applied phosphate. These results suggest that the mechanism of P-Zn interaction is not in the soil. This was also confirmed by the soil analysis where zinc availability was not much affected due to increased phosphate application in the post harvest soil samples.