Impact of dissolving agents on soil availability and plant content of phosphorus from Eppawala rock phosphate

Abstract

Phosphorus deficiency is a major problem in tropical soil and it directly influence the productivity of crops. Sandy regosol is a major group of soil in Batticaloa District, Sri Lanka. Productivity of most legume crops limited in the sandy regosol due to the lack of the availability of phosphorus. Usually Phosphorus deficiency can be managed by using a proper phosphorus source in sandy regosol. Eppawala rock phosphate is a cheap and available source of phosphorus in Sri Lanka and due to its low solubility, it has been confirmed as a constrain of direct use to annual crops as a phosphate source and it was limited only to perennial crops. A study was conducted from July to September 2017 to increase the solublility of various rates of Eppawala rock phosphate to give 18kg P2O5/ha, 36kg P2O5/ha and 54kg P2O5/ha solely (control) and in combination with dissolving agents compost, sulphuric acid and triple super shosphate (TSP). These 12 treatments replicated three times in a Completely Randomized Design (CRD) in a factorial manner. Soil and plant phosphorus contents were recorded at 2 weeks interval upto harvesting. The data were statistically analyzed using SAS and difference between treatment means was compared using Duncan’s Multiple Range Test (DMRT). Results revealed that the application of ERP with dissolving agents increased soil phosphorus content from 90.12mg/kg to 465.998 mg/kg (at eighth week). Among all applications 54kg P2O5/ha in the form of ERP with dissolving agent triple super phosphate proved to be the best to increase soil and plant phosphorus content. The results of this study suggested that incorporation of triple super phosphate and ERP could be used as effective way to increase the phosphorus availability in soil.