水土保持措施对坡耕地土壤养分时空变异影响

以水保林地、水平梯田及地埂植物带组成的水土保持措施体系和无水保措施布置坡耕地为研究对象,结合传统统计分析和ArcGIS地统计分析方法,研究不同深度土壤养分随时间及空间(垂直和水平)变化特征。结果表明,(1)所选研究区内土壤有机质、全氮、全磷和有效磷含量均随着土层深度的增加而降低,同一坡位高度,有水土保持措施坡耕地土壤养分含量比无措施坡耕地高,且土壤养分在垂直方向上相对均匀分布。(2)从各水土保持措施对不同深度土壤养分含量的影响来看,在水土保持体系内,0~15 cm和15~30 cm土壤有机质含量依次为:水保林地>水平梯田>地埂植物带,全氮、全磷和有效磷含量依次为:地埂植物带>水平梯田>水保林地。在无措施对照区,土壤有机质、全氮和有效磷含量两层次均顺坡逐渐增高,而全磷两层次分布均呈:中坡位无措施区>下坡位无措施区>上坡位无措施区。不同深度土壤有机质、全氮、全磷和有效磷含量均随月份变化先增加后损失,但其变化程度因水土保持措施不同而不同。(3)经统计分析表明,水土保持措施区0~15 cm土壤有机质和全氮变异系数大于无措施对照区,但土壤全磷和有效磷变异系数正好相反;无措施对照区15~30 cm土壤有机质、全氮、全磷和有效磷变异系数大于水土保持措施区。水土保持措施与不同深度土壤养分之间均呈极显著正相关关系,0~15 cm和15~30 cm土壤全氮和有效磷之间均呈显著正相关,而0~15 cm和15~30 cm其他各指标关系间均呈极显著正相关关系。

Effect of Soil and Water Conservation Measures on Temporal and Spatial Variability of Soil Nutrients in Sloping Farmland

We selected soil and water conservation measures (SWCMs) system composed of forest land with soil and water conservation,level terrace and terrace covered with vegetation and the corresponding control areas (CAs,slope farmland without measures) as the research objects.Traditional statistic and ArcGIS geo-statistic analysis methods were used to research the variation characteristics of soil nutrients distribution at spatial (horizontal and vertical) and temporal scale.The results showed as followed:(1) The contents of four indicators (soil organic matter,total N,total P and Olsen P) decreased with the increase in soil depth.At the same slope position,soil nutrient content in SWCMs was higher than that in CAs.And the distribution of soil nutrient was relatively uniform at the vertical soil profile of SWCMs.(2) Soil organic matter (SOM) at both 0-15 cm and 15-30 cm soil depths showed:forest land with soil and water conservation ＞ level terrace ＞ terrace covered with vegetation in SWCMs system.And the contents of total N,total P and Olsen P showed the same trend:terrace covered with vegetation ＞ level terrace ＞ forest land with soil and water conservation.In CAs,the contents of SOM,total N and Olsen P were increased gradually along slope downward.The distribution characteristics of total P at horizontal and vertical soil layer of CAs were:the middle slope ＞ downhill ＞ uphill.The contents of SOM,total N,total P and Olsen P in different depths increased first and then decreased with months,but the change was different among different soil and water measures.(3) The result of statistical analysis showed that at 0-15 cm soil depth,the variation coefficient of SOM and total N was greater in SWCMs than in CAs,but that of total P and Olsen P was greater in CAs than in SWCM.At 15-30 cm soil depth,the variation coefficient of SOM,total N,total P and Olsen P was greater in CAs than in SWCMs.There was a significant positive correlation between SWCMs and soil nutrient contents at different depths.And total N was significantly positively correlated with Olsen P at 0-15 cm and 15-30 cm soil depths,but the very.significant positive correlation was found among other indicators at 0-15 cm and 15-30 cm soil depth.