Some properties of granulated superphosphate and its behaviour in the soil

Abstract

The composition and particle size distribution of granules in commercial granulated single superphosphate has been shown to be very variable, the distribution of micronutrients amongst granules being less uniform than the distribution of macronutrients. Under farming conditions, the amounts of fertilizer copper and zinc in granulated fertilizer applied to individual plants varied widely, although no correlation between amount applied and plant uptake was found. Most phosphate, copper and zinc moved into the soil through very small pores that developed within granules. A residual skeleton of anhydrite and poorly soluble phosphates remained in the soil. This granular residue persists in some soils for long periods and its properties may affect the residual value of the fertilizer.