猪场废水灌溉对土壤有机氮矿化的根际激发效应与影响机制

The contradiction of water shortage in China is becoming more and more serious. Livestock wastewater, as a replacing water resource has received continuous attention. Currently , some studies showed that the irrigation of reclaimed water facilitated the form transformation and bioavailability improvement of nitrogen in the soil. The applicant have found that swine wastewater irrigation could enhance the nitrogen supply capacity of soil, but the mechanism is not clear. Based on the safe farmland irrigation technologies of swine wastewater and the mineralization theory of soil organic nitrogen , our study aim to investigate the rhizosphere priming effect of swine wastewater irrigation on soil organic nitrogen mineralization and the relevant mechanism. There are two innovation points in our research as follows: (1) With the lysimeter and the image-monitoring analytical system and other situ observation platform, and the combination of indoor incubation experiment, the effect of swine wastewater irrigation on migration regularity of nitrogen and root activity parameters will receive real-time supervision to clarify. The mineralization characteristics of organic nitrogen and rhizospheres priming effect in field.(2)we focus on the reasonable interdisciplinary research, select the mineralization process of soil organic nitrogen as the hitting poing explore the driving factors of mineralization of soil organic nitrogen under swine wastewater irrigation from the angle of mineralization hotspot in rhizosphere ,and discuss the pathway of organic nitrogen mineralization mediated by rhizosphere soil-root exduates-microorganism system and the key interaction mechanism. Our study can provide theory guidence for the safe and efficient use of swine wastewater and the improvement of nitrogen use efficiency ,which is of great significance.

我国水资源紧缺的矛盾日益凸显，养殖废水作为替代水源受到越来越多的关注。研究表明，城市再生水灌溉有利于土壤氮素形态的转化与活性的提高。申请者前期研究发现，猪场废水灌溉能够提高土壤供氮能力，但机制尚不清楚。本项目基于猪场废水安全回灌农田技术与土壤有机氮矿化理论，研究猪场废水灌溉条件下土壤有机氮矿化的根际激发效应与影响机制。该项目研究特色及创新之处在于：一、依托地中渗透仪及根系原位监测系统等田间原位观测平台，结合室内培养试验，实时监测猪场废水灌溉对氮素运转规律及根系活力参数的影响，研究田间状态下有机氮矿化特征及根际激发效应；二、关注学科间的合理交叉，以土壤有机氮矿化过程为切入点，从根际“矿化活性热区”微域角度，挖掘猪场废水灌溉土壤有机氮矿化的驱动因子，探讨根际土壤-根系分泌物-微生物系统介导有机氮矿化的途径及其关键互作机制。本项目研究意义在于为安全高效利用猪场废水及提高氮素利用效率提供理论指导。

随着水资源短缺矛盾的不断加剧，作为替代水资源的养殖废水农业利用日益受到重视。养殖废水灌溉能够增加土壤养分含量，促进氮素的迁移转化，但影响氮素转化的驱动因子和机制尚不明确，而且猪场废水含有的一些危害物质尤其是病原菌、抗生素抗性基因和重金属等，不仅会导致土壤环境恶化、农业生产力下降，还会影响生态环境和食品安全。.本项目通过地中渗透仪田间微区灌溉试验和室内培养试验，研究了猪场废水灌溉土壤氮素在时间和空间上的变化特征，并根据氮平衡原理对农田氮输入和氮输出项进行分析，测算了作物整个生育期内的氮矿化量，探讨了激发土壤氮素矿化的驱动因子。同时，利用根箱模拟试验，研究了猪场废水灌溉土壤典型污染物的迁移累积特征。结果表明：猪场废水高氮处理PWH对氮素矿化有着显著的正向激发效应，该处理土壤硝酸还原酶、pH值及细菌数量对氮的矿化影响表现出较大的直接正效应，且脲酶、蛋白酶活性的提高及固氮基因（nifh）丰度的降低也是氮素矿化的主要原因。猪场废水灌溉条件下，等量高氮施肥PWH处理较低氮施肥PWL处理显著增加了微生物α多样性，而低量氮肥处理PWL显著增加了人类疾病（如Cancers）的代谢通路。同时，猪场废水灌溉增加了农田尤其是根际土壤中有效铜（24%）、有效锌（293%）、抗生素及其抗性基因丰度的检出率，而添加生物炭能够降低土壤总抗生素浓度和作物根部铜的累积，却提高了土壤抗性基因的丰度。