Compared to discharge into waterways, land application of treated municipal effluent (TME) can reduce the need for both inorganic fertilizers and irrigation. However, TME irrigation may result in the accumulation of phosphorus (P) or trace elements in soil, and increased salinity and sodicity, which could damage soil structure and reduce infiltration. TME irrigation can also result in groundwater contamination through nitrate leaching or surface water contamination through runoff. This study aimed to evaluate the effects of increasing TME irrigation rates on quantity and quality of leachate and pasture growth in a lysimeter experiment using a Fluvial Recent soil and a Fragic Pallic soil. Pasture growth in the lysimeters was up to 2.5-fold higher in the TME treatments compared to the non-irrigated treatments. There were no signs of toxicity or accumulation of B, Al, Cd, Cu, Fe, Mn, As, and Zn. TME significantly increased the concentration of P and Na in the pasture. Nitrogen leaching from the lysimeters was negligible (< 1 kg/ha-1 equiv.) in all treatments, but mineral N accumulated in the soil profile of the highest application rate (1672 mm/yr). Although more P was added than removed in pasture, the rate of accumulation indicated that over a 50-year period, P will still be within the current New Zealand thresholds for grazed pastures. Sodium accumulated in the soil columns in all the TME treatments. The rate of accumulation was not proportional to the TME application rate, indicating that Na was moving down through the soil profile and leaching. Results indicate a low to moderate risk of sodicity in soil or toxicity in plants caused by Na.

中文翻译：

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使用经过处理的市政污水进行牧场灌溉的风险和收益：溶菌计案例研究，新西兰坎特伯雷。

与排放到水道相比，经过处理的市政污水（TME）的土地施用可以减少对无机肥料和灌溉的需求。但是，TME灌溉可能会导致土壤中磷（P）或微量元素的积累，并增加盐分和碱度，这可能会破坏土壤结构并减少渗透。TME灌溉还可能因硝酸盐浸出而导致地下水污染，或因径流而导致地表水污染。这项研究的目的是在使用河流最近的土壤和脆弱的pallic土壤的溶渗仪实验中，评估提高TME灌溉速率对渗滤液和牧场生长数量和质量的影响。与非灌溉处理相比，TME处理中的溶菌计中的牧场生长高出2.5倍。没有B，Al，Cd，Cu，Fe，Mn，As和Zn的毒性或积累迹象。TME显着提高了牧场中P和Na的浓度。在所有处理中，从溶渗仪中浸出的氮几乎可以忽略不计（<1 kg / ha-1当量），但矿质氮以最高施用量（1672 mm / yr）积累在土壤中。尽管磷的添加量大于牧场中的清除量，但累积速率表明，在50年的时间里，磷仍将在新西兰目前放牧草场的阈值之内。在所有TME处理中，钠都累积在土壤柱中。积累速率与TME施用量不成比例，表明Na在土壤剖面中向下移动并浸出。结果表明，Na引起的土壤中碱度或植物毒性的中低风险。