Comparative Study of Guizhou Sloping Land Soil and Water Conservation Effect of the Three Cropping Patterns

Surface cover degree, monthly variation of topsoil water content, loss of soil and nutrient in alfalfa-corn intercropping, strip rotation cropping and corn monoculture were studied in this paper. Then soil and water conservation effect of these planting modes were compared. Results showed that surface cover degree was high during the all rainy season in both alfalfa-corn intercropping and strip rotation cropping mode, with slope field covered by vegetation all the year round. Roots of alfalfa grew well, which not only improved the root biomass in 0-20 cm layer, enhanced the capacity of the infiltration of rainwater to soil, protected biodiversity, but also reduced surface off and soil erosion of 39.3% and 59.3%. Strip rotation cropping could also reduce surface off and soil erosion of 10.4% and 21.3%. Both alfalfa-corn intercropping and strip rotation cropping increased soil moisture in rainy season and before rainy season, whilst reduced loss of organic matter (caused by soil erosion) of 29.9%-52.4%, total N of 26.7%-54.9%,total K of 27.3%-70.9%, slow available K of 21.4%-58.9%, increased corn production of 33.0-35.9%. Moreover, there was 13664kg/hm2 in alfalfa-corn intercropping, which was 4.1 times higher than common mode. There was 12492 kg/hm2 in strip rotation cropping which was 2.7 times higher than common mode.