摘要
耕作能直接造成大量的土壤向坡下运动 ,却在以往土壤侵蚀研究中被忽视。为了定量评价耕作侵蚀以及在坡耕地土壤侵蚀中的重要性 ,通过耕作侵蚀示踪试验及铯 - 1 37示踪的方法对黄土区耕作侵蚀及其对总土壤侵蚀贡献的空间格局进行了研究 ,取得了如下结果 :( 1 )一次耕作造成的单宽土壤搬运量为 2 3.60～ 45 .68kg/m,并从坡地上部和下部向中部逐渐变大 ;( 2 )耕作侵蚀强度主要集中在 70 0～ 2 0 0 0 t/km2 和- 1 2 0 0～ - 2 0 0 0 t/km2 之间 ,分别发生在坡地凸型和凹型部位 ;( 3)总土壤侵蚀强度主要集中在 2 60 0～890 0 t/( km2· a)和 - 2 75 0～ - 3390 t/( km2· a)之间 ,分别发生在坡地凸型部位与凹型部位的上部及坡地凹型部位的下部 ;( 4 )耕作侵蚀占总土壤侵蚀的百分比 ,主要集中在 1 0 %～ 2 8%、- 2 7%～ - 398%和 36%～ 5 4 %之间 ,从坡顶向坡底 ,依次分布在两种侵蚀皆呈侵蚀的部位、耕作侵蚀呈沉积而总土壤侵蚀呈侵蚀的部位及两种侵蚀皆呈沉积的部位。结果表明 ,耕作侵蚀是黄土区坡耕地的一种重要的土壤侵蚀 ,是总土壤侵蚀的重要组成部分 ,水土保持工作中应充分考虑耕作侵蚀及其对总土壤侵蚀贡献的空间格局。
Tillage implements can cause a large amount of downhill movement of soil, but it is neglected in the past research on soil erosion. To quantitatively evaluate tillage erosion and its importance to soil erosion on sloping cultivated land, authors study the spatial patterns of tillage erosion and its contribution to total erosion in the loess region of China by conducting a tillage experiment and using 137Cs tracing method. Tillage manner is animal powered contour plowing and tillage depth is about 16cm on study site. Slope length and slope gradient are about 30m and about 4°~29° respectively, and slope profile is convexity in the upper segment and concavity in the lower segment on study site. In the tillage experiment, the small cubes with volume of 1cm 3 and specific gravity of 1.15 g/cm 3 is used as tracers. In 137Cs tracing method, the space for soil sampling is about 3m. Study shows that soil flux per tillage operation is 23.60～45.68 kg/m on study site. The segments of study site with soil flux less than 30.00 kg/m, between 30.00 and 40.00 kg/m, and greater than 40.00 kg/m account for 25.08%, 37.27%, and 37.65% of the whole slope respectively, and distribute in the upper and the lower parts, the upper middle and the lower middle parts, and the middle part of sloping land respectively. The spatial variation of slope gradient with projected slope length determine the spatial variation of soil flux per tillage operation with the projected length. Tillage erosion intensities mainly range from 700 to 2000 t/km 2. The eroded area accounts for 43.92% of the sloping land, distributing on the convexity. Tillage deposition intensities mainly range from 1200 to 2000 t/km 2. The deposition area accounts for 43.92% of the sloping land, distributing on the concavity. Erosion and deposition are not observed in the transition position from convexity to concavity. The spatial variation of topography curvature with projected slope length determine the spatial variation of tillage erosion intensity with projected slope length. The total erosion intensities mainly range from 2600 to 8900 t/(km 2·a). The total erosion area accounts for 81.24% of the sloping land, distributing on the convexity and the upper segment of concavity. The total deposition intensities mainly range from 2750 to 3390 t/(km 2·a). The total deposition area accounts for 18.76% of the sloping land, distributing on the lower segment of concavity. The average total soil loss intensity is 4445.33 t/(km 2·a) and the sediment delivery ratio is 0.91. The integrated effect of slope gradient, slope length and topography curvature is responsible for spatial variation of total soil erosion intensity, and the relationship can be described by a linear equation of three variables. The spatial variation of percentage of tillage erosion intensity over total soil erosion intensity with projected slope length differs greatly in the 3 segments of sloping land. The first segment distributes on convexity of study site where both the tillage operation and the integrated erosion force produce net erosion. The percentages mainly range from 10% to 28% and the area accounts for 54.25% of the whole sloping land. The second segment distributes on the upper part of concavity where tillage operation causes soil deposition, but the integrated erosion force produces net erosion. The percentages mainly range from -27% to -398% and the area accounts for 34.86% of the whole sloping land. The third segment distributes on the lower part of concavity where both the tillage operation and the integrated erosion force produce soil deposition. The percentages mainly range from 36.54 to 54% and the area accounts for 10.89% of the whole sloping land. The results show that tillage erosion is one of important soil erosion processes and one of important components of total erosion on sloping cultivated land in the loess region of China. Great attention should be paid to the spatial patterns of tillage erosion and its contribution to total erosion in the soil conservation management.
出处
《生态学报》
CAS
CSCD
北大核心
2003年第7期1328-1335,共8页
Acta Ecologica Sinica
基金
国家自然科学基金资助项目 ( 4 9871 0 5 1 )
黄土高原土壤侵蚀与旱地农业国家重点实验室基金资助项目 ( 0 2 -B0 0 4)
中国科学院知识创新工程重要方向资助项目 ( KZCX3 -SW-44 2 )
陕西省人事厅留学基金资助项目~~
关键词
黄土区
耕作侵蚀
总土壤侵蚀
空间格局
示踪
耕作搬运
贡献
loess region
tillage erosion
total erosion
spatial patterns
tracing
tillage translocation
contribution
