地理学报 ›› 2003, Vol. 58 ›› Issue (1): 147-154.doi: 10.11821/xb200301018

• 论文 • 上一篇    

北京地区农田氮素养分随地表径流流失机理

黄满湘,章申,张国梁,张秀梅   

  1. 中国科学院地理科学与资源研究所,北京 100101
  • 收稿日期:2002-06-08 修回日期:2002-10-11 出版日期:2003-01-25 发布日期:2003-01-25
  • 作者简介:黄满湘 (1967-), 男, 博士后.主要从事环境生物地球化学和地理信息系统研究。 E-mail: huangmx@lreis.ac.cn
  • 基金资助:

    国家自然科学基金重大项目(397901000)

Losses of Nitrogen Nutrient in Overland Flow from Farmland in Beijing under Simulated Rainfall Conditions

HUANG Manxiang, ZHANG Shen, ZHANG Guoliang, ZHANG iumei   

  1. Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China
  • Received:2002-06-08 Revised:2002-10-11 Online:2003-01-25 Published:2003-01-25
  • Supported by:

    National Natural Science Foundation of China, No.397901000

摘要:

田间模拟降雨径流试验研究了北京地区农田暴雨径流氮素流失与雨强、作物覆盖、施肥因子的关系,以及侵蚀泥沙的粒径分布特征和对氮的富集作用。结果表明:(1) 降雨强度越大,地表径流模数和侵蚀模数增大,氮素流失越多;作物覆盖有效地减少地表水土和颗粒态氮流失;(2) 颗粒态氮浓度占径流全氮浓度的88.9 % (施尿素) 和98 % 以上 (未施氮肥),是农田径流氮损失的主要形态;(3) 施用化学氮肥增大了农田径流溶解态氮浓度,化学氮肥容易通过地表径流流失;(4) 侵蚀泥沙的团聚体组成和原来土壤有很大差异,粒径 <0.25 mm的团聚体,尤其是含氮量较高的 <0.045 mm 团聚体的富集是侵蚀泥沙富集氮的主要原因。减少地表径流和土壤侵蚀,降低表土速效氮含量是减少农田地表径流氮养分流失的关键。

关键词: 模拟降雨;地表径流;侵蚀泥沙;溶解态氮;颗粒态氮;团聚体;富集系数

Abstract:

Rainfall simulation experiments were performed to evaluate the contribution of both particulate N and dissolved N to losses of nitrogen by comparing the difference of the N concentrations and the yields in runoff from three tilled plots A, B and C, and the effect of fertilizer applications on them. The catchment area of the plot is 2 m × 5 m each with a slope of 5 degrees. A and B were bare and unfertilized, and C was fertilized with granular urea (360 N kg/ha) idle 35%. These results indicate that: (1) higher rainfall intensity results in higher discharge, sediment yield and losses of N, even lower cover rate significantly reduces discharge, and sediment yield and loss of N; (2) particulate N was the dominative form of N loss in surface runoff, added fertilizer N may suffer loss by runoff dissolved N form. Mechanism of soil aggregates detachment by rainfall and loss by runoff was investigated to seek explanation for the enrichment of PN in eroded sediment to original soil. The results showed that the aggregate size distribution of the eroded sediment was drastically different to that of the original soil. Aggregates smaller than 0.25 mm constituted more than 81% of the sediment as compared with only 16% in the original soil. More than 99% of total N transported by runoff was in the particulate form, whereas 78% of particulate N lost with finer aggregates smaller than 0.25 mm. About 44% of particulate N lost with finer aggregates smaller than 0.045 mm. ERN decreased as the erosion process continued. A higher percentage of aggregates smaller than 0.25 mm, especially the enrichment of aggregates smaller than 0.045 mm which has a high concentration of nitrogen is responsible for the enrichment of N in eroded sediment.

Key words: simulation rainfall, overland flow, sediment, aggregate, dissolved nitrogen, particulate nitrogen, enrichment ratio (ER)