不同施肥处理稻田系统磷素输移特征研究

Phosphorus loss and migration characteristics in paddy fields under different fertilization treatments

  • 摘要: 磷是水体富营养化限制性元素, 近年来由于磷肥的过量施用, 农田迁移的磷素已成为水体磷素的主要来源。本研究通过野外测坑定位试验, 研究有机肥处理(OT)、混施肥处理(MT)和化肥处理(CT)3种施肥处理下, 稻田中磷素的迁移流失特征及这3种处理对水稻产量和磷素利用率的影响, 以探求稻田系统的最佳施磷方式。结果表明, CT、MT和OT 3种施肥方式的磷径流流失负荷分别为0.56 kg(P)·hm-2、1.13 kg(P)·hm-2和4.20 kg(P)·hm-2, 渗漏流失负荷分别为0.42 kg(P)·hm-2、0.44 kg(P)·hm-2和0.45 kg(P)·hm-2; 磷的径流流失占流失总量的56.86%~90.38%, 是水稻田磷素流失的主要途径。磷的径流流失主要受施肥和降雨的影响, 50%左右磷的流失发生在第1次径流过程; 磷素渗漏流失特征不受施磷处理的影响, 80%以上的流失发生在施肥后的前30 d。在磷素流失形态上, 坑面水、渗漏水和径流水中磷素的主要形态均为可溶性磷; 在土壤方面, MT处理和OT处理能保证土壤磷营养, CT处理的土壤有效磷和有机质含量则显著下降。3种施肥处理的水稻产量显著高于空白对照, 且MT最高, 为6 728.84 kg·hm-2; 磷肥利用率CT和MT处理显著高于OT, CT和MT间差异不显著。综合比较, 混施肥处理在磷素流失、土壤养分利用和水稻产量等方面更符合我国生态农业发展的要求。

     

    Abstract: Phosphorus is a restricted element as it causes eutrophication of especially still water systems. Due to the excessive application of phosphate fertilizers in recent years, farmlands have become the major source of phosphorus which causes water eutrophication. To determine optimal phosphorus applications in paddy fields, a field lysimeter experiment was conducted under different treatments of organic fertilizer (OT), mixed fertilizer (MT) and chemical fertilizer (CT). Phosphorus loss and migration characteristics in the fields under different treatments, and treatments effects on yield and phosphorus utilization ratio of paddy rice were analyzed. Results showed that runoff loads of phosphorus under CT, MT, and OT were 0.56 kg(P)·hm-2, 1.13 kg(P)·hm-2 and 4.19 kg(P)·hm-2, respectively. Also leaching loads of phosphorus under CT, MT and OT were 0.42 kg(P)·hm-2, 0.44 kg(P)·hm-2 and 0.45 kg(P)·hm-2, respectively. Phosphorus loss in paddy fields was mainly through runoff, accounting for 56.86%?90.38% of total phosphorus loss. Runoff of phosphorus was mainly driven by fertilizer dose and rainfall intensity, and the loss through the first runoff accounted for about 50% of phosphorus loss. Phosphorus leach was not influenced by phosphorus dose, and over 80% of phosphorus loss occurred in the first 30 days after fertilizer application. Soluble phosphorus was the main form of phosphorus in surface water, seepage water and runoff water. While it was possible for MT and OT to ensure sufficient phosphorus supply in soils, CT decreased Olsen-P and organic matter in soils. Yields of paddy rice under the three treatments were significantly higher than that under the control, among which MT had the highest yield (6 728.84 kg·hm-2). Phosphorus fertilizer use efficiencies under CT and MT were significantly higher than that under OT. In conclusion, MT was better fertilzation pattern for phosphorus loss control, soil nutrient utilization and paddy rice yield in eco-agricultural systems in China.

     

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