Enhanced efficiency phosphate fertilizers and phosphorus availability in Acrudox

摘要

The objective of this study was to evaluate the influence on P availability of the application of polymer-coated phosphate andorganophosphate fertilizers to the soil under different soil water matric potentials and contact times. The experiment was laid outin a randomized block design and replicated four times, with treatments distributed in a split-plot arrangement. The main plotcomprised four phosphate fertilizers (conventional mono-ammonium phosphate, MAP; polymer-coated mono-ammoniumphosphate, POL; pelletized mono-ammonium phosphate with filter cake, FC; and granulated mono-ammonium phosphate withswine compost, SC) and two soil water contents corresponding to two matric potentials (-10 and -50 kPa). The subplot comprisedsix contact times (2, 4, 6, 8, 10 and 14 days after fertilizer addition). P content was determined after extraction with Mehlich-1 orwater. The highest available P contents in soil were obtained using MAP (1474.3 mg dm -3 ) followed by POL (1355.7 mg dm -3 ), FC(1235.5 mg dm -3 ) and SC (804.2 mg dm -3 ). The available P contents during the 14 days of the experiment relative to the control(MAP) values ranged from 88.5 to 95.4% for POL, 83.2 to 84.4% for FC and 54.9 to 54.2% for SC. These results evidenced the effectsof the organic coating applied to the phosphate fertilizer on fertilizer solubility and the short-term release of P. A decrease in thesoil water matric potential decreased P availability in the short term for fertilizers with coating technologies, especially for SCcompared to MAP. This result indicates that organic coating technologies may hold promise for maintaining P availability over time.