ENHANCING PHOSPHORUS SOLUBILITY FROM ROCK PHOSPHATE INTEGRATED WITH FARMYARD MANURE IN P-DEFICIENT SOIL

Abstract

The aim of this study was to assess the solubility of phosphorus from rock phosphate incubated with farmyard manure under laboratory condition. The treatments were factorial combination of three rates each of RP (0, 2, and 4 tons ha-1) and farm yard manure (0, 10 and 20 tons ha-1). These treatments were applied to 100 g soil contained in plastic vials with three replications. Seven such sets of 27 vials each were prepared to represent seven incubation periods namely 0, 15, 30, 45, 60, 75, and 90 days. The results showed that Olsen -P improved significantly with increasing rate of rock phosphate from 0 to 4 tons ha-1 and that of farmyard manure from 0 to 20 tons ha-1. Initial available P content of soil was 4.59 mg kg-1 which enhanced up to 10.55 mg kg-1 as a result of 90 days incubation. Addition of rock phosphate and farmyard manure increased it to maximum value of 23.03 mg kg-1 with incorporation of rock phosphate at 4 tons ha-1 and farmyard manure at 20 tons ha-1. Thus, positive response of rock phosphate and farmyard manure was clearly evident on Olsen-P values due to enhancement of soil organic matter. It is concluded that there is potential for utilization of local rock phosphate by solubilising the P using farmyard manure. Soil incubation for the prolonged period of 90 days with rock phosphate and farmyard manure helped to enhance the solubility of P from rock phosphate. It is recommended that further experiments may be performed along with different bio-char, vermicompost, organic acids etc. which can help solubilise P from rock phosphate under field trials. For the first time, the feasibility of using agricultural fertilizer (manure) to increase the solubility of phosphorus from rock phosphate is experimentally substantiated. The practical value of this study is to achieve two effects simultaneously, namely, improving the fertility of agricultural lands depleted in phosphorus and utilizing agricultural fertilizer (manure).