Effect of sulphur added to phosphate rock on solubility and phytoavailability of phosphorus

For ground phosphate rock (GPR) to be applied as phosphorus fertilizer, the availability of phosphorus to plants needs to be improved. One possible way to achieve this is by adding sulphur, which will accelerate decomposition of phosphate in soil owing to the activation of microbiological processes. This study involved granulation of fertilizers composed of phosphate and sulphur mixed at 38:1 and 10:1 ratios and two analogous fertilizer variants but with added molasses as a source of organic carbon for sulphur bacteria. A small-scale industrial installation for production of multi-component fertilizers was used to make granular fertilizer by the compaction method. The granular fertilizers were then tested in an agricultural experiment. The fertilizer in which the phosphate to sulphur ratio was 10:1 produced better effects. Addition of molasses to the fertilizers did not improve their fertilizing capacity.