贵州省石漠化综合治理人工种草对土壤侵蚀的影响

Effect of Planting Grass on Soil Erosion in Karst Demonstration Areas of Rocky Desertification Integrated Rehabilitation in Guizhou Province

采用野外调查和室内分析相结合的方法,对贵州省盘县哮天龙小流域和晴隆县孟寨小流域坡耕地、人工草地和天然草地3种土地利用方式下土壤理化性质、抗剪强度和崩解速率进行研究,以揭示石漠化综合治理工程草地建设对土壤侵蚀的影响程度。结果表明:(1)在坡耕地上实施人工种草可有效改善土壤容重,调节土壤孔隙度,增加土壤保水能力,0-10cm,10-20cm和20-30cm土壤容重分别降低0.07%,17.83%和15.08%,土壤孔隙度分别增加0.01%,16.06%和13.26%,土壤含水量分别增加43.45%,43.61%和30.46%。(2)坡耕地实施人工种草措施后,土壤有机质含量相对增加77.24%,其中0-10cm,10-20cm和20-30cm土层土壤有机质含量分别增加48.06%,85.58%和107.78%,土壤全氮含量相对增加42.64%,土壤全磷含量相对增加45.24%,土壤全钾含量相对降低43.28%。(3)人工草地和天然草地相对坡耕地表现出良好的土壤抗侵蚀性能,人工草地土壤抗剪强度是坡耕地的2.08倍,天然草地是坡耕地的2.06倍。坡耕地0-10cm土层土壤表现出较高的崩解速率,随着土层深度的增加而减小。与此相反,人工草地和天然草地0-10cm土层土壤表现出较低的崩解速率,但随着土层深度的增加崩解速率表现出逐渐增大的趋势。(4)人工草地土壤相对坡耕地具有较小的容重、较高的土壤孔隙度和较强的抗剪强度,土壤整体的抗侵蚀性能强于坡耕地,在坡耕地上实施人工种草,蓄水保土效益非常明显。

By means of fields investigation and lab experiments,soil physical and chemical characteristics,shear strength and soil scouring modulus with different soil depth under planting grassland,nature grassland and slope farmland in Xiaotianlong and Mengzhai small watersheds were studied.The result showed that:(1)After planting grass,it was effective to reduce soil bulk density,improve soil porosity and SWC in slope farmland.Soil bulk density reduced by 0.07%in 0-10cm soil layer,17.83%in 10-20cm soil layer and 15.08%in 20-30cm soil layer.Soil porosity improved by 0.01%in 0-10cm soil layer,16.06%in 10-20 cm soil layer and 13.26% in 20-30cm soil layer.SWC improved by 43.45% in 0-10cm soil layer,43.61%in 10-20cm soil layer and 30.46% in 20-30cm soil layer.(2)After planting grass,it was effective to improve soil organic matter content in slope farmland and soil organic matter content increased by 77.27%.Soil organic matter contents increased by 48.06%,85.58%,107.78%in 0-10cm,10-20cm and 20-30cm soil layer,respectively.The soil total N content and soil total P content increased by 42.64% and 45.24%,the soil total K content decreased by 43.28%.(3)The shear strength of planting and nature grassland were 2.08,2.06times than that of slope farmland,so planting and nature grassland showed a good soil anti-erosion ability than slope farmland.Slope farmland soil in 0-10cm layer showed higher soil scouring modulus,which decreased with increasing soil depth.In contrast,planting and nature grassland soil in 0-10cm layer showed lower soil scouring modulus,which increased with increasing soil depth.(4)Compared with slope farmland soil,planting grassland had lower soil bulk density,higher soil porosity and shear strength.Therefore,it had an obvious benefit for getting water and soil conservation after planting grass in slope farmland.