The behaviour of raw bone-meal, steamed bone-meal, calcined bone-meal, rock-phosphate, calcined rock-phosphate and high grade basic-slag in water at different conditions showed that water plays an important role in the decomposition of these phosphates and remains active upto 50 to 60 days in the case of calcined rock, bone phosphates, basic-slag and rock-phosphate. In the case of raw and steamed bone-meals, water is also responsible to form organic acids which increase the rate of decomposition and improve the phosphate status in aqueous solutions. Carbon dioxide decomposed these phosphatic materials and efficiency of CO2 was more pronounced at the lower concentration. The relative solubility of CO2 and water followed the order: Raw Bone-Meal>Steamed Bone-Meal>Calcined Bone-Meal>High Grade Basic Slag>Calcined Rock Phosphate>Rock Phosphate. The suitability of these phosphatic fertilizers for different soil conditions are discussed.
Water insoluble phosphates
