Bone meal is a mixture of finely and coarsely ground animal bones and slaughter-house waste products. It is an organic source of phosphorous as well as calcium. The phosphorous content of bone meal varies from 20 to 25 per cent. Besides phosphorous, bone meal also contains to around 2-4 percent nitrogen. The fertilizer is recommended mainly at the time of planting.
Bone meal is primarily used as a slow release source of phosphorus. Finely ground bone meal ensures quicker release of nutrients.
Rock phosphate is a natural source of phosphorous mined from phosphorous containing mineral rocks. The reactivity of rock phosphate depends on the type of mineral and its inherent purity. Rock phosphate mined from the place Mussorie is called Mussoriephos.
Rock phosphate contains 18-20% phosphorous. The phosphorous present in rock phosphate is insoluble in water. However, it will become available to plants slowly under acidic conditions.
Rock phosphate is most reactive when it is finely ground and incorporated into warm, moist, acidic soils. Though the availability of rock phosphate is slow, it has a good residual effect.
Single Super Phosphate
Single Super Phosphate (SSP) is the first fertilizer produced commercially. It is also known as ordinary superphosphate and normal superphosphate.
Phosphorous is present mostly in water solouble form. It contains 18 per cent phosphorous as major nutrient. It also provides 12 per cent sulphur and 21 per cent calcium. It is a grey powder with good keeping quality.
Single Super Phosphate is an excellent source of three plant nutrients. The presence of both phosphorous and sulphur in the fertilizer is beneficial in soils where both nutrients are deficient.
Triple Super Phosphate
Triple Super Phosphate is the concentrated super phosphate containing 46 per cent phosphorous. It is suitable for all crops and all soils. In acid soils, it should be used in conjunction with organic manure. It can be applied at the time of land preparation or at sowing/transplanting. It is available in granular and non granular form. Most part of phosphorous in triple super phosphate is in water solouble form.
Triple Super Phosphate contains 15 per cent calcium also. It is also suitable to leguminous crops as no nitrogen fertilization is needed to supplement biological nitrogen fixation.