贵州坡耕地三种种植模式的水土保持效果对比研究

通过研究紫花苜蓿—玉米间作、作物分带轮作和玉米单作3种种植模式下地表覆盖度和表层土壤含水量月变化,年均土壤和养分流失量以及产量等,比较不同模式的水土保持效果。结果表明:紫花苜蓿—玉米间作与分带轮作模式可保持坡耕地全年覆盖,并在整个雨季保持较高的覆盖度。紫花苜蓿根系发达,增加了0—20cm耕层土壤中的根量,增强了土壤的渗透能力,保护了生物多样性,可减少地表径流39.3%,减少土壤侵蚀59.3%;分带轮作可减少地表径流10.4%,减少土壤侵蚀21.3%;两种模式都提高了雨季前和雨季耕层土壤中的水分,减少了水土流失引起的有机质流失29.9%～52.4%,全N流失26.7%～54.9,全钾流失27.3%～70.9%,缓效钾流失21.4%～58.9%,提高玉米产量33.0%～35.9%;紫花苜蓿—玉米间作还可收获紫花苜蓿干草13 664kg/hm2,复合产量是农民习惯的4.1倍;分带轮作可收获大豆、红薯、油菜等,复合产量为12 492kg/hm2,是农民习惯的2.7倍。

Comparative Study on Soil and Water Conservation Effect of the Three Cropping Patterns on Slope Land in Guizhou Province

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.Then soil and water conservation effect of these planting modes were compared.Results showed that surface cover degree was high during all the 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 soil infiltration,protected biodiversity,but also reduced 39.3% and 59.3% of surface runoff and soil erosion,respectively.Strip rotation cropping could also reduce 10.4% and 21.3% of surface runoff and soil erosion.Both alfalfa—corn intercropping and strip rotation cropping increased soil moisture in rainy season and before rainy season,while reduced loss of organic matter(caused by soil erosion) by 29.9%~52.4%,26.7%~54.9% for total N,27.3%~70.9% for total K,21.4%~58.9% for slow available K,increased corn production by 33.0%~35.9%.Moreover,The yield was 12 492 kg/hm2 in strip rotation cropping which was 2.7 times higher than conventional mode.The yield was 13 664 kg/hm2 in alfalfa—corn intercropping,which was 4.1 times higher than conventional mode.