不同农作方式红壤坡耕地土壤氮素流失特征

采用径流小区法研究了6种不同农作方式土壤N素的流失特征。结果表明，同顺坡农作方式相比，其它农作方式均有明显控制土壤N素流失的作用，水平草带、水平沟、等高耕种、休闲、等高土埂等农作方式分别减少土壤N素流失量43．46％、46．55％、71．36％、77．05％和87．92％，等高耕种、等高土埂、休闲等农作方式控制土壤N素流失优于水平沟和水平草带农作方式，坡耕地土壤N素的流失途径主要为径流流失，约占土壤N素流失量81．9％－93．4％，径流流失的N素中又以水溶态N素为主，约占径流流失N素的78％－87．6％，坡耕地土壤N素流失主要集中在5－8月份，占全年流失量的85％－100％。

Characteristics of nitrogen loss from sloping field in red soil area under different cultivation practices

The characteristics of nitrogen loss under six types of cultivation practices were studied in Lanxi Water and Soil Conservation Supervision Station of Zhejiang Province. The results showed that compared with the traditional cultivation practice (treatment 5, straight farming), the other cultivation practices including grass strip, contour ditch, contour farming, contour dam, and fallow decreased soil nitrogen loss significantly, and the percentages of nitrogen loss under the 5 types of cultivation practices decreased by 43.46%, 46.55%, 71.36%, 77.05%, and 87.92%, respectively. Soil nitrogen lost mainly with runoff, and it accounted for 81.9-93.4% of total soil nitrogen loss. Dissolved nitrogen was the major form of lost nitrogen and accounted for 78-87.6% of total lost nitrogen in runoff. Nitrogen loss was occurred mainly during May to August, and it accounted for 85-100% of total annual nitrogen loss.