An Evaluation of Asphalt Coatings on Phosphorus Fertilizers
1967
Hall, J. K. | Baker, D. E.
Controlling the dissolution rate of P from fertilizer by use of an effective asphalt coating on water-soluble superplaosphate did not result in increased recovery of added P by successive crops. Average growth response of plants and amounts of P absorbed from this coated fertilizer by successive croppings were less than those obtained by plants grown with water-insoluble dicalcium phosphate and calcium metaphosphate. Four to five times as much of the coated as uncoated superphosphate was required to supply equal amounts of P to millet. With reduced availability of P in the coated fertilizer, a much larger portion of the plant P was absorbed from the indigenous soil P. The asphalt coating' which was effective on superphosphate was not effective on diammonium phosphate or magnesium ammonium phosphate because ot failure to adhere to the surface of the crystals. Other similar asphalt coatings were not effective on superphosphate.
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