College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China.
College of Agricultural Science and Engineering, Hohai University, Nanjing 210098, China.
Int J Environ Res Public Health. 2021 Mar 24;18(7):3348. doi: 10.3390/ijerph18073348.
In southern China, the growing period of rice is synchronized with the rainy period, and the loss of nutrients (such as nitrogen) due to unreasonable irrigation and drainage, along with rainfall and runoff, has become the main source of agricultural nonpoint source pollution. The laws of runoff and nitrogen loss in paddy fields under different irrigation and drainage modes are not clear. In this study, field experiments were adopted to observe the runoff and nitrogen loss under typical rainfall and throughout the whole growth period. The results showed that, compared with the traditional irrigation and drainage mode, the controlled irrigation and drainage mode reduced the drainage of two typical rainfall processes by 47.5% and 31.3% and the peak drainage by 38.9% and 14.4%. Compared with those under the traditional irrigation and drainage mode, the average concentrations of total nitrogen, nitrate nitrogen, and ammonium nitrogen under the controlled irrigation and drainage mode were reduced by 22.2%, 22.7%, and 27.8%, respectively, during the whole rainfall process on July 21 and were decreased by 27.1%, 11.4%, and 25.6%, respectively, on August 25. In irrigated rice areas, under the controlled irrigation and drainage mode, drainage was reduced after two intercepts through paddy fields and drainage ditches. The nitrogen concentration in the drainage ditch decreased due to the increase in retention time and the effect of the ditch and field wetland. Compared with the traditional irrigation and drainage mode, the total nitrogen, nitrate nitrogen, and ammonium nitrogen loads of the controlled irrigation and drainage mode were reduced by 69.8%, 65.3%, and 69.7%, respectively.
在中国南方，水稻的生长周期与雨季同步，由于不合理的灌溉和排水，以及降雨和径流导致的养分（如氮）流失，已成为农业面源污染的主要来源。不同灌溉排水模式下稻田的径流和氮素流失规律尚不明确。本研究采用田间试验，观测典型降雨和整个生育期的径流和氮素流失。结果表明，与传统灌溉排水模式相比，控制灌溉排水模式可减少两次典型降雨过程的排水量 47.5%和 31.3%，峰值排水量减少 38.9%和 14.4%。与传统灌溉排水模式相比，控制灌溉排水模式在 7 月 21 日整个降雨过程中，总氮、硝态氮和铵态氮的平均浓度分别降低了 22.2%、22.7%和 27.8%，在 8 月 25 日分别降低了 27.1%、11.4%和 25.6%。在水稻灌区，控制灌溉排水模式下，稻田和排水渠两次截留后排水量减少，排水中氮浓度因滞留时间增加和沟渠、田间湿地的作用而降低。与传统灌溉排水模式相比，控制灌溉排水模式的总氮、硝态氮和铵态氮负荷分别减少了 69.8%、65.3%和 69.7%。
