强度耕作对^(137)Cs、^(210)Pb_(ex)和有机质剖面分布的影响  

Profile Variations of ^(137)Cs, ^(210)Pb_(ex) and SOM as Affected by Intensive Tillage on Steep Slope

作　　者：李勇[1] 白玲玉[1] 张兴昌[1] Lindstrom M L Bork H R 

机构地区：[1]中国农业科学院农业环境与可持续发展研究所,北京100081 [2]美国农业部土壤保持实验室 [3]德国基尔大学

出　　处：《水土保持学报》2003年第3期1-4,73,共5页Journal of Soil and Water Conservation

基　　金：国家自然科学基金资助项目(40071054和90202005);IAEAResearchContractNo.12323/RegularBudgetFund.

摘　　要：很少有关于直接测定强度耕作侵蚀引起土壤退化过程的报道。我们的目的是确定应用137Cs和210Pbex直接定量评价耕作侵蚀对土壤有机质(SOM)坡面运移影响的可能性。我们在黄土高原陡坡耕地上进行了50次犁耕活动,并将与其相临的另一块陡坡耕地作为对照。在对照坡地不同坡位,137Cs浓度均匀分布于上部0～30cm土层,而210Pbex浓度在坡上部和坡中部随土层深度增加呈现线性递减,在坡下部呈指数函数递减。0～30cm土层中土壤有机质含量显著大于30cm深度以下土层,并在坡中部和坡下部呈现与210Pbex类似的土壤剖面分布特征。与对照坡地比较,50次犁耕活动导致坡上部、坡中部0～45cm土层的SOM含量分别降低了38%和47%,坡下部0～100cm土层中的SOM含量却提高了18%。坡上部土壤剖面中137Cs浓度的加权平均值从1.48Bq/kg降低到0.29Bq/kg,坡中部从2.53Bq/kg减少到0.33Bq/kg,坡下部从1.48Bq/kg提高到2.81Bq/kg。210Pbex浓度的剖面加权平均值在坡上部从27.71Bq/kg下降到6.15Bq/kg,在坡中部和坡下部分别从35.46Bq/kg和25.53Bq/kg降低到1.57Bq/kg和19.40Bq/kg。137Cs和210Pbex的剖面分布与SOM在p<0.001水平呈显著相关,相关系数R2值在对照坡地为0.81～0.86,在犁耕实验坡地为0.86～0.91。实验结果表明。Few direct measurements have conducted to investigate the dynamic process of soil degradation as affected by intensive tillage at the field level. Our objective is to test the potential of 137Cs and 210Pbexfor directly assessing the movement of SOM on the slope land as affected by tillage operations. We conducted 50 plowing operations over a 5day period using a donkeydrawn moldbordplow on steep backslope of the Chinese Loess Plateau. Profile variations of 137Cs, 210Pbex and SOM contents were measured at upper, mid, and lower portion of the slope after 50 plowing operations. Intensive tillage effects on 137Cs, 210Pbex and SOM contents were determined from a control slope adjacent to experimental slope. 137Cs concentration was uniformly mixed in the upper 0~30 cm of soil whereas 210Pbex showed a linear decrease at upper and mid portion, and an exponential decrease with depth on the lower portion of the control slope. SOM contents of 0~30 cm layers were much higher than the soil layers below 30 cm on the control slope, and showed a similar decrease pattern to profile pattern of 210Pbex on the mid and lower portion of the control slope. Fifty 50plowing operations resulted in a decrease of SOM content (g/kg) by 38% and by 47% for the soil layers of 0~45 cm at upper portion and mid portion, respectively. However, the lower position showed an increase of SOM content by 18% in the soil layers of 0~100 cm after 50 plowing operations. Weighed mean values of 137Cs concentrations decreased from 1.48 Bq/kg to 0.29 Bq/kg at upper position, from 2.53 Bq/kg to 0.33 Bq/kg at mid position, and increased from 1.48 Bq/kg to 2.81 Bq/kg at lower position. Weighed mean values of 210Pbex concentrations decreased from 27.71 Bq/kg to 6.15 Bq/kg at upper position, from 35.46 Bq/kg to 1.57 Bq/kg at mid positi

关 键 词：土壤侵蚀 强度耕作侵蚀 土壤有机质 剖面分布 土壤退化 土壤质量 定量评价 铯 铅 同位素 

分 类 号：S157.1[农业科学—土壤学]