| Serious soil erosion leads to severe soil quality degradation in the black soil region ofNortheast China in recent years. Soil enzyme activities can be used as soil biological indicesand soil fertility indices. Therefore, carrying out research on the influence of soil erosion onspatial distribution of soil enzyme activities could provide scientific basis for soil qualityimprovement and sustainable utilization of soil resources. In this study, Binzhou River Basin,which located in Bin county, Heilongjiang province, was taken as the research area.According to field investigation combining with laboratory analysis, we revealed spatialdistribution of soil urease, soil alkalin, soil invertase and soil protease on watershed and slopescale, analyzed effects of soil erosion, soil aggregates and soil fertility index on spatialdistribution of soil enzyme activities.The mainresults were as follows:(1) Spatial distribution characteristics of soil enzyme activities were studied. Soil ureaseactivities varied from525.0to2009.0mg/kg·d, and its activity in downstream was bigger thanthat in midstreamand upstream; soil alkaline phosphatase activities varied from1582.0to3245.0mg/kg·d, and followed as the orders upstream<midstream<downstream; soil invertaseactivities varied from11.4to26.3mg/g·d, and increased form upstream to downstream, butdid not reached significant difference; soil protease activities vary from0.09to0.47mg/g·d,and showed the sequences of midstream>upstream>downstream, and it in upstream anddownstream significantly reduced by20.0%and54.3%respectively, compared withmidstream. Soil alkaline phosphatase activities in sloping scale were found in the ordersof.upslope position<midslope position <downslope position; soil urease activity and soilinvertase activity were not obvious along the slope length; soil protease activities showed thesequences of upslope position> midslope position> downslope position; soil alkalinephosphatase, soil urease and soil invertase activities reached maximum at downslope; soilprotease reached maximum at upslope of midstream. Soil alkaline phosphatase activities werethe biggest among four kinds of enzyme activities.(2) Effects of soil erosion on soil enzyme activities were revealed. Spatial distribution ofsoil urease, soil alkaline phosphatase and soil invertase activities were corresponded to soil erosion distribution characteristics, and these three soil enzyme activities showed thesequences of deposition area> soil erosion-deposition area> soil erosion area, whichreflected effects of soil erosion on three kinds of soil enzyme activities. Soil proteaseactivities showed the orders of soil erosion-deposition area> soil erosion area> depositionarea. Soil urease, soil alkaline phosphatase and soil invertase activities showed the oppositetrend to soil erodibility K value distribution at watershed and sloping scales, while soilprotease activities distribution was similar to the spatial distribution of soil erodibility Kvalue. The relationship between both of soil urease and soil alkaline phosphatase activitieswith soil erodibility K value were significantly negative correlation respectively; but therewas a significant positive correlation between soil protease activities and soil erodibility Kvalue.(3) The relationship between four types of soil enzyme activities and soil aggregates,soil fertility indices and soil erodibility was comprehensively analyzed. The key factor ofsoil urease and soil alkaline phosphatase activities was mean weight diameter of soilaggregates, but the key factor affecting soil protease activities was soil organic matter. |
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