Effect of Applied Phosphorus on the Availability of Micronutrients in Alkaline-Calcareous Soil

Abstract

The present experiment was carried out to study the effect of applied phosphorus on the availability of micronutrients in alkaline-calcareous soil. For this purpose an incubation experiment was conducted in the laboratory of Soil and Environmental Sciences Department, The University of Agriculture Peshawar Pakistan during 2009 with variable amounts of phosphorus, i.e. 0, 30, 60, 90, 120 and 150 kg P ha^-1 in the form of single super phosphate. The experiment was conducted in completely randomized block design with three replications consisted of 100 g of soil in each pot. The experiment was incubated for 28 days under normal conditions. The soil was kept moist up to field capacity condition throughout the incubation period. Results regarding the effect of phosphorus application on the availability of micronutrients showed non-significant differences in the treatments of applied phosphorus, but the trend of each micronutrient was obvious. The overall results showed that as the application of phosphorus increases, the concentrations of B, Zn and Cu gradually decreases, which indicate negative interactions, while the concentrations of P, Fe and Mn increases perhaps due to positive interactions with applied phosphorus during incubation period. Results further showed as the applied P (from single super phosphate) increases the pH-values gradually decreases, which resulted significantly negative correlation with one another (r² = 0.83). These results indicate that with the application of P as single super phosphate reduced the pH of soil and has favorable effect on the solubility of micronutrients, specifically Fe and Mn in the alkaline-calcareous soils.

Keywords: Phosphorus, Micronutrients availability