西南地区红黄壤坡耕地可蚀性研究

Studies on Erodibility of Sloping Farmland on Red-Yellow Soils in Southwest China

针对西南地区典型红黄壤坡耕地,采用同时Wischemeier、Williams的计算公式、诺谟图查值、美国通用水土流失方程(USLE)K值表查值法开展土壤可蚀性研究,结果表明:A、B、C土层的K总平均值分别在0.222~0.369、0.329~0.413、0.430~0.560和0.405~0.595之间(见表3)。各种方法计算出来的K值差距甚大,变异系数差别也很大,用Sharply A.与Williams J. R.提出的公式计算出的K值变异系数小,相对稳定和精确,是红黄壤坡耕地K值计算的适宜方法;红黄壤坡耕地A层的K值随着年份的增长,呈下降的趋势,整个土层可蚀性强、抗侵蚀弱,侵蚀的危害大。通过4年不同种植制度和利用类型的影响,不同土层的K值都下降,其中A层下降1.26%~12.34%,B层下降1.29%~13.80%,C层下降1.26%~10.82%,A、B、C三层平均下降3.17%~11.64%。不同种植制度和利用类型坡耕地K值下降幅度不一样,除工程梯化处理外,草地、分带轮作、经果林、粮草间作、植物篱、混交林处理的K值下降幅度都高于农民习惯,下降幅度从高到低的排列顺序是:草地 >分带轮作 >经果林 >粮草间作 >植物篱 >混交林。种树种草,有利于坡耕地可蚀性的改善和耕地质量的提高。玉米与其它植物间套作,提高覆盖度和增加生物种类,也有利于坡耕地可蚀性的改善。

With Wischemeier and Williams’s design formulas, nomograph and USA Universal Soil Loss Equation (USLE) K-value table, the study to typical sloping farmland on red-yellow soils in southwest showed that the mean K-values of A, B and C layer were 0.262 - 0.476, 0.308 - 0.578 and 0.237 - 0.595 (table 3), respectively. The K-value and variation coefficient were very different with different utilization methods, and Sharply and Williams’s calculation formula in EPIC model was relatively constant and accurate, as the suitable utilization method. The K-value of A layer trended down with age, and the whole A layer had a serious harm of soil erosion with strong erodibility and weak anti-erodibility. The K-values of A, B and C layer turned down 1.29% - 13.80%, 1.29% - 13.80% and 1.26% - 10.82% with different planting systems and land use types in 4 years, and the whole layer turned down 3.17% - 11.64%. The drops in K-value of different planting systems and land use types were not same: Excepted terracing treatment, others drop more than CK, and grass >rotation >fruit forest >grass and crop intercropping >hedgerow >mixed forests. Planting trees and grasses was conducive to improve the erodibility and the quality of the sloping farmland. The maize intercropped and relay intercropped with other plants could improve the coverage and species of the sloping farmland, could also improve the erodibility of the sloping farmland.