Liang Xin-Qiang, Li Hua, Chen Ying-Xu, He Miao-Miao, Tian Guang-Ming, Zhang Zhi-Jian
Dep. of Environmental Engineering, College of Natural Resources and Environmental Science, Zhejiang Univ., Hangzhou, China.
J Environ Qual. 2008 Mar-Apr;37(2):712-7. doi: 10.2134/jeq2007.0073.
A near-trench paddy field experiment with five urea application rates (0-360 kg N ha(-1) in 90-kg increments) was conducted on a paddy soil in the Taihu Lake Region of China to elucidate N losses through lateral seepage during three rice (Oryza sativa L.) growing seasons. The total N (Nt), NH4(+) -N, and NO3(-) -N concentrations in the lateral seepage water increased with increasing N rates. The seasonal Nt fluxes by lateral seepage varied from 6.8 to 25.6 kg N ha(-1) for urea application rates of 90 to 360 kg N ha(-1). Lateral seepage accounted for 4.7 to 6.6% of the Nt applied, implying that lateral seepage was an important pathway of N loss from near-trench paddy fields. The cumulative N loss via lateral seepage was significantly related to N fertilization rate (P = 0.05). Floodwater level was also identified as a main factor affecting N losses via lateral seepage from paddy fields, as indicated by a positive linear relationship (R2 = 0.43) between floodwater level and daily lateral flow during the flooded period (P = 0.05). Under the conditions of these experiments, a shallow floodwater depth of 50 mm, urea application rates of 90 kg N ha(-1) or less, and no rainfall within 1 wk after N application reduced N losses by lateral seepage from paddy fields.
在中国太湖地区的水稻土上进行了一项近沟渠稻田试验，设置了5个尿素施用量水平（0 - 360 kg N ha⁻¹，增量为90 kg），以阐明三个水稻（Oryza sativa L.）生长季期间通过侧向渗漏造成的氮损失。侧向渗漏水的总氮（Nt）、铵态氮（NH₄⁺ - N）和硝态氮（NO₃⁻ - N）浓度随施氮量增加而升高。对于90至360 kg N ha⁻¹的尿素施用量，侧向渗漏的季节性Nt通量在6.8至25.6 kg N ha⁻¹之间变化。侧向渗漏占施氮总量的4.7%至6.6%，这意味着侧向渗漏是近沟渠稻田氮损失的重要途径。通过侧向渗漏的累积氮损失与施氮量显著相关（P = 0.05）。淹水水位也被确定为影响稻田侧向渗漏氮损失的主要因素，这体现在淹水期淹水水位与日侧向流量之间呈正线性关系（R² = 0.43）（P = 0.05）。在这些试验条件下，50 mm的浅淹水深度、90 kg N ha⁻¹或更低的尿素施用量以及施氮后1周内无降雨，可减少稻田侧向渗漏造成的氮损失。
