新疆绿洲区连续五年施用沼液对农田土壤质量的影响

Effect of biogas slurry on soil quality of intensive plantation field in Xinjiang oasis for 5 years

以施用化肥为对照,通过5年田间小区试验,研究沼液灌溉对绿洲设施蔬菜地土壤质量的影响。试验结果表明:连续施用沼液能够有效调节绿洲农田耕层土壤酸碱度,有利于改良碱性土壤;沼液灌溉能够显著提高设施蔬菜地土壤肥力,尤其是表层土壤中有机质和全氮、全磷、速效氮、有效磷、速效钾、钙、铁、锌和铜等植物必需营养元素含量;然而,连续施用沼液也会导致表层土壤电导率显著升高,土壤中重金属元素显著积累,虽然5年内设施蔬菜地土壤盐分和重金属等有害元素含量均在蔬菜种植允许范围内,但随着沼液灌溉年限的增加,土壤存在次生盐渍化现象和重金属超标风险,尤其以Cd、As和Ni的风险最大。

A 5-years field trial was established in Yili area to investigate the effects of the biogas slurry on soil quality in oa- sis farmland. The control group was treated by chemical fertilizer and the experimental groups were treated by biogas slurry. The results showed that application of biogas slurry to the same soil for 5 years was helpful for adjusting soil pH of intensive vegetable field, and improved soil alkaline soil of intensive vegetable field. Moreover, application of biogas slurry to the same soil for 5 years could also enhance soil fertility of the oasis farmland, particularly the contents of the essential nutrients required for plant growth in soil depth of 20 cm, such as soil organic matter, total N, total P, available N, available P, available K, total Ca, total Fe, total Zn and total Cu. However, application of biogas slurry to the same soil for 5 years could lead to electrical conductivity increase significantly in soil depth of 20 cm, and the heavy metals were accumulated re- markably in the topsoil of oasis farmland. At the end of 5 years field trial, no soil secondary salinization was detected in the soil of oasis farmland, and the concentrations of soil heavy metals were lower than the criteria of National Soil Quality Stand- ards. With the biogas slurry irrigation duration prolonged, there were potential risk of soil secondary salinization and soil heavy metals exceeding, especially Cd, As and Ni of the soil.