紫色丘陵区不同土地利用方式土壤剖面微团聚体组成及分形特征

Composition and Fractal Features of Soil Micro-aggregates Under Different Land-use Types in Purple Hilly Area

通过野外采样和室内分析相结合的方法,研究了紫色丘陵区不同土地利用方式下的土壤剖面微团聚体组成及分形特征。结果表明：林地、花椒地、旱地、水田和柑橘园土壤微团聚体组成以0.25-0.05mm粒级为优势粒级,0.05-0.01mm次之,占比18.80%-35.57%,〈0.001mm粒级含量最少,为0.33%-2.57%;0—20cm土层土壤微团聚体平均重量比表面积（MWSSA）表现为林地（161.04cm2/g）〉柑橘园（134.49cm2/g）〉花椒地（117.31cm2/g）〉水田（100.67cm2/g）〉旱地（96.94cm2/g）,且林地土壤微团聚体MWSSA显著大于其他土地利用方式;0—20cm土层林地土壤团聚状况和团聚度显著高于其他土地利用方式,且其团聚体状况分别比花椒地、旱地、水田和柑橘园提高了16.55%,20.15%,11.23%和7.68%;20—40cm土层各土地利用方式土壤微团聚体分形维数D值表现为柑橘园（2.41）〉林地（2.40）〉花椒地（2.32）〉水田（2.31）〉旱地（2.12）,且旱地土壤微团聚体D值显著低于其他利用方式;5种土地利用方式土壤微团聚体分形维数与各因子的相关性分析有一定的相似性,同时也存在一定的差异性。因此,不同土地利用方式下土壤微团聚体分形维数在一定程度上能表征土壤物理性质的优劣、养分肥力的高低以及抗蚀能力的强弱。

Through filed sampling and laboratory analysis,the composition and fractal features of profile soil micro-aggregates in purple hilly area with different land use types were studied.The results showed as follows：Among woodland,pepper filed,dry land,paddy and citrus orchard,micro-aggregates of 0.25to0.05 mm was dominant,followed by micro-aggregates of 0.05 to 0.01 mm,which appropriated 18.80% to35.57% of the total samples,the least were〈0.001 mm,which proportion was between 0.33%to 2.57%.In 0—20cm soil layer,the annual mean weight soil surface area（MWSSA）sequence was woodland（161.04cm2/g）〉citrus orchard（134.49cm2/g）〉pepper land（117.31cm2/g）〉paddy（100.67cm2/g）〉dry land（96.94cm2/g）.In this layer,the MWSSA of woodland micro-aggregates was significantly higher than other land use types,which aggregate state and aggregate degree superior than others as its aggregate state showed a 16.55%,20.15%,11.23% and 7.68% higher than pepper filed,upland,paddy and citrus orchard,respectively.In 20—40cm soil layer,the fractal features Dof each land use type is like citrus orchard（2.41）〉woodland（2.40）〉 pepper field（2.32）〉 paddy（2.31）〉upland（2.12）,the D value of upland is significantly lower than other lands.The fractal features of these five land correlate with the result of factor analysis,though some inconsistent exist.Hence,the fractal features of micro-aggregates in different land use type can be,to some extent,seen as an index to characterize superior or inferior of soil physical properties,fertility level and corrosion resistance.