陕西省耕地土壤可蚀性因子

目的]土壤可蚀性因子是计算土壤侵蚀的一个重要因子,对陕西省耕地土壤可蚀性因子展开研究,可为陕西地区的耕地土壤侵蚀计算及评价提供科学依据。方法]以陕西省9个地区的耕地土壤实测数据为基础,利用通用土壤流失方程USLE(universal soil loss equation)、修订土壤流失方程RUSLE2(revised universal soil loss equation version 2)、侵蚀生产力影响模型EPIC(erosion productivity impact calculator)中可蚀性因子K值的计算公式以及几何平均粒径公式和几何平均粒径—有机质Dg-OM公式,计算不同耕地土壤质地条件下的土壤可蚀性因子。结果]RUSLE2的极细砂粒转换公式在陕西黄土丘陵沟壑区平均低约14.53%,在陕南地区平均高约32.91%,使用修正公式后平均误差分别为7.81%和13.14%;对比分析K值的估算值与实测值,子洲县实测K值为0.002 69〔(t·hm2·h)/(hm2·MJ·mm)〕,Dg-OM模拟计算均值为0.0297〔(t·hm2·h)/(hm2·MJ·mm)〕;水蚀预报模型WEPP(water erosion prediction project)中的细沟间可蚀性(Ki)和细沟可蚀性(Kr),与USLE的K值相关系数分别为0.738 6和0.607 4。结论]极细砂粒转换修正公式的计算误差小于RUSLE2模型;Dg-OM模型适合陕西黄土丘陵沟壑区及长武县、杨凌区和安康市典型耕地土壤;WEPP中Ki和Kr,当土壤砂粒含量小于30%,USLE的K值与WEPP的Ki和Kr值有强相关性。

Cultivated Soil Erodibility in Shaanxi Province

Objective] Soil erodibility is a key factor of calculating the soil erosion, and the investigation of cultivated soil erodibility provide the scientific basic to calculate and evaluate soil erosion in Shaanxi Province.Methods] The soil data was from nine experimental plots that distributed in Shaanxi Province of China. To calculate soil erodibility of these areas, we utilized five commonly used models, which are universal soil loss equation(USLE), revised universal soil loss equation version 2(RUSLE2), Erosion productivity impact calculator(EPIC), geometric mean diameter(Dg) and geometric mean diameter-organic matter(Dg-OM).Results] The equation of very fine sand(VFS) in RUSLE2 underestimated 14.53% of VFS content in hilly area of Losses Plateau of Shaanxi Province and overestimated 32.91% of VFS content in the Southern Shaanxi Province. Based on the measured values, the revised equation reduced the average calculation error of VFS content to 7.81% and 13.14% respectively. Secondly, comparison of K values, the measured K value in Zizhou County is 0.002 69(t·hm²·h)/(hm²·MJ·mm)], the mean K value of Dg-OM model is 0.029 7(t·hm²·h)/(hm²·MJ·mm)]. Thirdly, the interrill erodibility(K_i) and rill erodibility(K_r) parameters in water erosion prediction project model(WEPP) were calculated and the correlation of erodibility parameter between K_i, K_r and K of USLE were 0.738 6 and 0.607 4.Conclusion] The average calculation error of revised equation of very fine sand is less than the equation of very fine sand in RUSLE2. Dg-OM model was suitable for calculation the soil erodibility in hilly area of Losses Plateau of Shaanxi Province and the area of Changwu County, Yangling District and Ankang City. Moreover, K_i and K_r parameters in WEPP was found the good correlation of erodibility parameter between USLE and WEPP model when the sand content was less than 30%.