The effect of rock phosphate-enriched compost on the yield and phosphorus nutrition of rye grass

We evaluated the effect of compost enriched with rock phosphate on the yield and phosphate nutrition of rye grass in a calcareous clay loam soil. Enriched compost was prepared by composting either Mussoorie rock phosphate (MP) or Hyper rock phosphate (HP) separately with wheat straw for up to 120 days. A significant amount of insoluble P was solubilized from both kinds of rock phosphates and converted to water soluble, organic, and formic acid soluble P fractions during composting. MP-enriched compost (MPEC) and HP-enriched compost (HPEC) contain 0.30% and 0.34% water soluble P205, 1.94% and 1.42% organic P 2 O 5 2.82% and 3.28% formic acid soluble P 2 O 5 , and 1.76% and 1.18% insoluble P 2 O 5 , respectively. In a greenhouse study, the yield of ryegrass (three cuttings) with both enriched composts was not significantly different from that of single superphosphate fertilizer (SSP). Phosphorus fractions of soil before sowing and after harvesting the rye grass showed that fixation of P with native soil calcium was much higher with SSP than with enriched composts. No significant differences were observed between MRP and HRP.