奶牛场废水灌溉不同水分处理对土壤质量及硝态氮淋溶的影响

The Effect of Dairy Effluent Irrigation with Different Water Treatments on Soil Properties and Nitrate Leaching

以小白菜为研究对象进行奶牛场废水灌溉试验,试验设水质和灌水下限两个因素,水质处理分原污水灌溉WW和再生水灌溉RW2个处理,灌水下限分60%田间持水量M6,70%田间持水量M7,80%田间持水量M8 3个水平。试验结果表明,原污水灌溉和再生水灌溉会影响土壤的化学性质,导致土壤pH值有明显变化,而EC则无明显变化。奶牛场废水及其再生水灌溉均会增加土壤速效氮、速效磷和有机质;污水灌溉和再生水灌溉土壤速效氮随灌水下限的升高而降低,而土壤速效磷和有机质则随灌水下限的升高而增大。土壤硝态氮的测定结果表明,在有小白菜生长的情况下,土壤硝态氮含量随小白菜的生长而减少,随土层深度的加深而降低,奶牛场废水灌溉引起地下水的硝态氮污染的可能性较小。总体而言,奶牛场废水可直接用于灌溉,较高的水分下限有助于提高土壤肥力和减小硝态氮的淋溶。

Field experiments of dairy effluent irrigation were conducted, with Chinese cabbage as a case study. The research investigated the effects of two kinds of irrigation water quality and three different water stress levels on soil properties and nitrate leaching. Raw dairy effluent （WW） and EM treated dairy effluent （RW） were used to irrigating cabbage. The levels were 60% field capacity （M6）, 70% field capacity （M7）, and 80G field capacity （M8） as the lower limit of irrigation. Results showed that EM treated/ without treated dairy effluent irrigation had no significant effect on EC after plant harvests, but there were significant effects on the values of soil pH, available N, available P and organic matter. Furthermore, soil available N increased with soil water contents. However, soil P and organic matter decreased with the decline of water stress. The results also showed that NO3-N concentrations decreased with time and soil depth, which suggested that risk of NO3-N leaching to ground induced by dairy effluent irrigation was low when cabbage was growing. In general, dairy effluent can be used to irrigation without EM treatment. Higher water moisture treatment helps to improve soil fertility and decrease NO3-N leaching.