宁夏第二次土壤普查结果表明,灌淤耕地速效磷含量明显提高,平均含量由1985年的16.3 mg/kg增加到现在28.04 mg/kg.吴忠市利通区东塔乡国家农业科技示范园区磷肥肥效试验研究表明:土壤速效磷含量在50～60 mg/kg高水平下,小麦套玉米施磷效果较低,小麦玉米总产量肥料函数效应达显著水平.施P2O5最大量114kg/hm2,产量最大为12 245 kg/hm2,肥科农学效率为4.43 kg/kg P2O,肥料农学效率随施肥量增加而降低,施有机肥(45 t/hm2)条件下施磷无效;水稻施磷也无效.但为保持土壤养分平衡,小麦套种玉米、水稻分别需施P2O5 89、107kg/hm2.土壤含磷中下等水平,水稻施磷效果显著,特别是配施氮钾肥处理的磷肥农学效率最高达26.6 kg/kgP2O5.P2O5施量达到135 kg/hm2时则减产.当施P2O5量>64 kg/hm2时产量随施磷量增加而降低,在此施磷量下产量最高为10 158 kg/hm2,磷肥农学效率23.3 kg/kg P2O5.%The Second Soil Census of Ningxia showed that the content of available phosphorus (FRP) in anthro-pogenic-alluvial soil of irrigation areas was improved obviously, and the average content of FRP was increased from 16.3 mg/kg to 28.0 mg/kg in 1985. Fertilization experiments in Dongta village of Wuzhong showed that application of phosphate fertilizer did not affect the crops in the soil containing 50 ～ 60 mg/kg FRP. The more fertilizer used, the lower fertilizer efficiency produced. The maximum fertilizer efficiency was of 4.4 kg. It had little impact on crop yield when applying P2O5 combined with organic manure. However, P2O5 should be applied with the amount of 90 kg/hm2 to keep the soil nutrient in balance. Though there was a negative effect of phosphate fertilizer applied in paddy fields, P2O5 should be applied with an amount of 92 kg/hm2 to keep the paddy soil available phosphorus in balance. Reasonable application amount of P2O5 in paddy field was better when the soil phosphorus content was in middle or lower level. The yield of rice was decreased with the amount of P2O5 applied higher than 64 kg/hm2 and fertilizer efficiency on crops was at 23.3 kg.
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