Response of maize to different phosphorus levels under calcareous soil conditions

A field experiment was conducted to investigate the effect of different levels of phosphorus on the yield and P uptake by maize [Zea mays cv. Jalal) on calcareous soil (19% lime on w/w basis) of Peshawar soil series [Piedmont alluvium, silty clay loam, Ustochrept]. The P treatments included 0 (control), 45, 90, 135 and 180kg as P2O5 per ha were arranged in randomized complete block design (RCBD) with three replications. The results showed that maize plant height, number of cobs per plot, grain and biomass yields increased with increasing levels of phosphorus. The increase in grain yield of maize over control was 17.8, 26.4, 50.6 and 47.1 % and biomass by 21.08, 37.06, 37.19, and 42.13 % with application 45, 90, 135 and 180 kg P2O5 per ha, respectively. The increase in yield and yield parameters above 135 kg per ha P application was non-significant, rather grain yield decreased when supplied with 180 kg P2O5 per ha. Tissue P concentration significantly increased with increasing levels of P but with variable pattern at all the given stages of the crop growth. During the initial growth viz. vegetative stage, the differences between control and P applied plots as well as among different P levels were more wider than latter stages that could be associated to the dilution effect or translocation of P from leaves to grains. Soil solution and AB-DTPA extractable P concentration determined at different stages of crop also tended to increase with increases in applied P levels. The VCR values revealed that P applied at the rate of 135 kg P2O5 per ha was economical with VCR of 3.41:1. Based on higher crop growth and yield and P concentration in tissue and soil, it was concluded that application of 135 kg P2O5 per ha could be the appropriate dose of P for maize under the prevailing highly calcareous soil conditions.