长三角地区典型稻作农业小流域氮素平衡及其污染潜势

Balance and Pollution Potential of Nitrogen in a Typical Rice-Based Agricultural Watershed of Yangtze River Delta Region

江苏省句容市陈武镇水库流域是以稻作为主的农业小流域,在长三角地区颇具典型性。于2007年5月至2008年4月在该流域进行定位观测与现场调查,通过估算氮素平衡来分析预测流域农田氮污染潜势。结果表明,研究时段内流域氮素输入量为1 589.1 t,输出量为1 168.4 t。化肥氮输入是农田氮素的最主要来源,占氮输入总量的67.2%;而作物收获是农田氮输出的主要方式,占氮输出总量的46.7%。水田和旱地氮平衡均处于盈余状态,盈亏率分别为20.5%和52.4%,氮素利用率分别为33.6%和34.9%,利用率较低。水田47.8%的氮素以气态形式损失,气态氮和储存在土壤中的氮素极易导致大气和水体污染。

The Chenwu Town Reservoir Watershed of Jurong, Jiangsu Province, is a typical rice-based agricultural watershed in the Yangtze River Delta region of China. Based on the data collected from stationary observation and field investigation of the rice-based agricuhural watershed from May 2007 to April 2008, nitrogen flow was balanced for the analyses and prediction of pollution potential of the farmland nitrogen to the watershed. Results show that the total input of nitrogen was 1 589. 1 t, while the total output of nitrogen was 1 168.4 t in the watershed during the period. Fertilizer application was the dominant source of nitrogen input, accounting for 67.2% , and harvest of crops was the major way of nitrogen output, accounting for 46. 7% o Balancing of input with output showed N surplus in both paddy fields and upland fields, of 20. 5% and 52.4%, respectively, demonstrating low nitrogen use efficiency, being 33.6% and 34. 9%, respectively. In paddy fields, about 47. 8% of the N input was lost in gaseous form. The gaseous nitrogen and the remaining nitrogen in soil are ready pollutants to the air and waterbodies.