碳含量对再生水灌溉土壤氮素迁移转化规律的影响

Effects of carbon content on transport and transformation discipline of nitrogen in soil with wastewater irrigation

为深入了解碳含量对再生水灌溉系统中氮素迁移转化的影响,该研究进行了碳含量影响下的再生水灌溉系统氮素迁移转化规律试验。利用不同碳含量的再生水灌溉种植在土柱中的黑麦草,测定各试验周期内灌溉水、土壤溶液和排水中不同形态氮的含量,分析不同生育期作物干物质产量和氮含量。结果表明,随灌溉水进入系统的氮素约有34%可被作物吸收利用,62%可通过反硝化作用去除或调节土壤氮库中的氮量,随水分下渗到根系层以下并随排水排出系统的氮量仅占灌溉水中氮量的3%～4%。从作物长势、干物质量和氮的利用量看,高碳处理优于低碳处理。试验条件下,再生水中碳含量较高时有利于氮素的转化、作物吸收利用以及氮的反硝化作用。研究结果对于以灌溉利用为目的的污水处理,具有一定的指导意义。

To understand the impact of carbon content on nitrogen transport and transformation in wastewater irrigation systems, soil column experiments were conducted. Soil columns with ryegrass growing in them were irrigated with primarily treated effluent （high carbon content） and secondarily treated effluent （low carbon content）. Samples of irrigation water, soil solutions from 10, 40 and 70 cm beneath soil surface, and drainage were collected during each irrigation event for analysis of ammonia, nitrate and total nitrogen. Dry matter yields of ryegrass were recorded and total nitrogen in them were measured. The results showed that about 34% of the nitrogen from irrigation water was uptaken by crop, 62% was removed through denitrification or deposit in the soil nitrogen pool. The amount of nitrogen that infiltrated into soil deeper than root zone was only 3% - 4% of the amount in irrigation water. For the dry matter yield and the amount of nitrogen utilized by crop, columns irrigated with high carbon content wastewater were better than columns irrigated with low carbon content wastewater. Higher carbon content was benefit to the transformation of nitrogen, its uptaken by crop and removal through denitrification.