沼肥替代化肥对设施蔬菜产量和土壤养分及重金属累积的影响

针对盲目施用沼肥可能带来的土壤环境问题,该研究采用5年8茬的设施番茄-甜椒田间轮作试验,研究不同沼肥和化肥配比对蔬菜产量、设施土壤氮磷养分及重金属累积的影响.结果表明:在等氮钾养分投入下,沼肥和化肥以不同比例配施的各处理没有影响蔬菜产量;氮素盈余和0~180cm土层土壤全氮含量随沼肥施用比例增加没有显著差异;磷素盈余随沼肥施用比例增加显著增加,完全沼肥处理0~30cm土层土壤Olsen-P及CaCl2-P含量分别达到151和8.0mg/kg,高于其他2个处理,且明显超出环境阈值.与完全沼肥处理相比,减量沼肥施用(3/5沼肥处理)明显降低了土壤氮素淋洗风险和磷素累积.与不施肥处理相比,施用沼肥后30~60、60~90、150~180cm土层土壤全Hg含量均低于不施肥处理;除30~60cm土层使用沼肥处理土壤中全As含量显著高于不施肥处理,其他土层各处理间均没有显著差异,而完全沼肥处理全Cr、全Cd、全Pb含量有所下降,且全Pb含量下降最为显著,但均没有出现重金属污染风险.沼肥替代化肥施用可有效实现废弃物中的养分资源循环利用,但增加菜田土壤磷素累积和淋失风险,本研究为设施菜田合理施用沼肥提供技术支持,为实现沼肥资源的循环利用和化肥替代模式提供理论参考.

Effects of biogas manure replacing chemical fertilizer on accumulation of nutrient and heavy metal in greenhouse vegetable soil

Abstract: Unreasonal application of biogas manure discharged from the biogas plants in livestock farms increased the environmental risk. In this study, 5-year with 8 seasons of tomato-pepper rotating protected-field experiment was conducted to investigate the effects of different applied proportions of biogas manures and chemical fertilizer (100% biogas manures, 3/5 biogas manures plus 2/5 chemical fertilizer, 2/5 biogas manures plus 3/5 chemical fertilizer, 3/5 biogas manures and unfertilized treatments) on vegetable yield and soil accumulation of nitrogen (N), phosphorus (P) and heavy metals, in order to support the possibility of biogas manure to replace chemical fertilizer. The results showed that there were no significant effects on vegetable yields among the treatments with 100% biogas manures, 3/5 biogas manures plus 2/5 chemical fertilizer, 2/5 biogas manures plus 3/5 chemical fertilizer treatments with the same N and potassium (K) input. No significant differences were investigated in the N surplus and soil total N in 0-180 cm soil depth after 5 years experiment. However P surplus significantly increased with the applied proportion of biogas manures. The contents of Olsen-P and CaCl2-P in the surface soil layer (0-30 cm) reached to 151 and 8.0 mg P/kg in treatment with 100% biogas manures application, respectively, much higher than other treatments, which significantly exceeded environmental threshold. Compared with the treatment with 100% biogas manures application, reduced biogas wastes application (3/5 biogas wastes) significantly decreased the nitrate leaching risk and P surplus. Compared with unfertilized treatment, the contents of total Hg in surface soil layer (0-30 cm) and totoal As content in the soil layer (0-180 cm) slightly increased, whereas the contents of total Cr, Cd and Pb in soil decreased, especially Pb, in the treatments with biogas manures application. No heavy metal pollution risk was observed in all treatments. Biogas manure replacing chemical fertilizer can effectively achieve the waste recycling utilization, but increase the risk of soil P accumulation and leaching.