长期畜禽养殖污水灌溉对土壤养分和重金属积累的影响

Effects of Long-term Irrigation of Livestock Farm Wastewater on Nutrients and Heavy Metals in Agricultural Soils

在浙北地区选择了16个样区（包括7个水田样区和9个蔬菜地样区），每个样区同时采集了畜禽养殖污水长期灌溉农田与无污水灌溉历史的对照农田土壤样品，比较分析了土壤中养分和重金属积累状况。结果表明，长期畜禽养殖污水灌溉可明显增加表层土壤（0～20cm）有机C、全N、全P、Cu、Zn、As、Cd、盐分、NH4＋-N、NO3^- —N、有效P和有效K的含量，但对土壤pH、全K、Pb、Ni、Cr、Hg的影响不明显。畜禽养殖污水灌溉对蔬菜地的影响明显大于水田。典型样区土壤垂直剖面分析结果表明，长期畜禽污水灌溉也可对剖面中20～60cm土层的NH4^＋-N、NO3^- -N和有效P含量也产生一定的影响。

Sixteen sites of agricultural fields, including 7 paddy fields and 9 vegetable fields, were selected for studying the effects of long-term irrigation of livestock farm wastewater on soil quality. At each of 16 sites, soil samples were collected from both agricultural fields with and without irrigation of livestock farm wastewater, pH value, and concentrations of organic C, total N, total P, total K, NH4^＋ -N, NO3^- -N, available P, available K, dissolved salt, and heavy metals （Cu.Zn.Pb.Cd.As. Hg.Cr and Ni） in the soils were measured. The results showed that long-term irrigation of livestock farm wastewater, the concentra- tions of organic total N, total P, total Cu, total Zn, total As, total Cd, salt, NH4^＋ -N, NO3^- -N, available P, available K increased significantly. However, there is no significant effect on soil pH, total K, total Pb, total Ni, total Cr and total Hg. The effects were more significant in vegetable fields than paddy fields. The irrigation also increased vertical transfer of NH4^＋ -N, NO3^＋ -N, available P in soil profiles, the concentrations of NH4^＋ -N, NO3^＋ -N, available P in 20-60 cm depth were significantly higher in the fields with irrigation of livestock farm wastewater than those without the irrigation.