A glasshouse experiment was conducted to evaluate the agronomic potential of four partially acidulatedrock phosphates (PARP) in three representative soils sampled from subtropical China. The PARPs weremanufactured by ...A glasshouse experiment was conducted to evaluate the agronomic potential of four partially acidulatedrock phosphates (PARP) in three representative soils sampled from subtropical China. The PARPs weremanufactured by attacking a moderately reactive phosphate rock either with sulfuric acid alone or withcombination of sulfuric and phosphoric acids at 30 or 60 percent of acidulation. Shoot dry weight and Paccumulation of six successive cuttings of ryegrass were used to compare the agronomic potential of thesefertilizers with that of the raw rock phosphate (RP) and monocalcium phosphate (MCP). Results indicatedthat the effectiveness of various phosphates was determined both by the solubility of the phosphates andby the acidity and P-fixing capacity of the soils. The higher the watersoluble P contained, the better theeffectiveness of the fertilizer was. Although plant P accumulation of PARP treatments was constantly lowerthan that of MCP treatment, some PARPs could still get a dry matter production similar to that of MCPtreatment. PARP SP60, which was acidulated with a mixture of sulfuric acid and phosphoric acid at 60percent of acidulation and contained the highest soluble P, was as effective as MCP in terms of dry matterproduction on all the soils. 560 and C1, which were both acidulated with sulfuric acid with the formerat 60 percent of acidulation and the latter at 30 percent but with a further addition of monoarninoniumphosphate, were more than 80 percent as effective as MCP. Raw RP also showed a reasonable effectivenesswhich increased with soil acidity. It was suggested from the study that some of these PARPs could beexpected to have a comparable field performance as soluble P fertilizers in the acid soil regions.展开更多
Loss of ammonia-nitrogen to volatilization and the over application of phosphorus in agricultural wastewaters has led to excess phosphorus build up in topsoil and in surface waters. In order to increase the usable amo...Loss of ammonia-nitrogen to volatilization and the over application of phosphorus in agricultural wastewaters has led to excess phosphorus build up in topsoil and in surface waters. In order to increase the usable amount nitrogen in agricultural wastewaters, the wastewaters underwent a nitrogen treatment process consisting of a hanging basket biological filter. The filters utilized never before used biological growth media, rice hulls, to assist in the formation of a mature biofilms as the oxidation of ammonia to nitrate. The filter design was used on a lab scale that treated both artificial wastewater and dairy parlor wastewater treated with a lime precipitation step for phosphorus treatment. The filters were tested to see if bio-fouling occurred in the filter media bed under high nitrogen loading, if the rice hulls could withstand an extended time frame as bacterial growth media, and to see if the oxidation of ammonia to nitrate would occur. A 50% reduction in ammonia occurred between 30 and 48 hrs in each trial with eventual nitrite oxidation reported in the final two trials. Statistical analysis preformed determined that the ammonia removal rates at the beginning of both the synthetic wastewater and dairy parlor wastewater ten-day tests were statistically similar, but varied toward the end of the trials.展开更多
文摘A glasshouse experiment was conducted to evaluate the agronomic potential of four partially acidulatedrock phosphates (PARP) in three representative soils sampled from subtropical China. The PARPs weremanufactured by attacking a moderately reactive phosphate rock either with sulfuric acid alone or withcombination of sulfuric and phosphoric acids at 30 or 60 percent of acidulation. Shoot dry weight and Paccumulation of six successive cuttings of ryegrass were used to compare the agronomic potential of thesefertilizers with that of the raw rock phosphate (RP) and monocalcium phosphate (MCP). Results indicatedthat the effectiveness of various phosphates was determined both by the solubility of the phosphates andby the acidity and P-fixing capacity of the soils. The higher the watersoluble P contained, the better theeffectiveness of the fertilizer was. Although plant P accumulation of PARP treatments was constantly lowerthan that of MCP treatment, some PARPs could still get a dry matter production similar to that of MCPtreatment. PARP SP60, which was acidulated with a mixture of sulfuric acid and phosphoric acid at 60percent of acidulation and contained the highest soluble P, was as effective as MCP in terms of dry matterproduction on all the soils. 560 and C1, which were both acidulated with sulfuric acid with the formerat 60 percent of acidulation and the latter at 30 percent but with a further addition of monoarninoniumphosphate, were more than 80 percent as effective as MCP. Raw RP also showed a reasonable effectivenesswhich increased with soil acidity. It was suggested from the study that some of these PARPs could beexpected to have a comparable field performance as soluble P fertilizers in the acid soil regions.
文摘Loss of ammonia-nitrogen to volatilization and the over application of phosphorus in agricultural wastewaters has led to excess phosphorus build up in topsoil and in surface waters. In order to increase the usable amount nitrogen in agricultural wastewaters, the wastewaters underwent a nitrogen treatment process consisting of a hanging basket biological filter. The filters utilized never before used biological growth media, rice hulls, to assist in the formation of a mature biofilms as the oxidation of ammonia to nitrate. The filter design was used on a lab scale that treated both artificial wastewater and dairy parlor wastewater treated with a lime precipitation step for phosphorus treatment. The filters were tested to see if bio-fouling occurred in the filter media bed under high nitrogen loading, if the rice hulls could withstand an extended time frame as bacterial growth media, and to see if the oxidation of ammonia to nitrate would occur. A 50% reduction in ammonia occurred between 30 and 48 hrs in each trial with eventual nitrite oxidation reported in the final two trials. Statistical analysis preformed determined that the ammonia removal rates at the beginning of both the synthetic wastewater and dairy parlor wastewater ten-day tests were statistically similar, but varied toward the end of the trials.
