陇中坡地不同退耕模式对土壤团粒结构分形特征的影响

Effect of Different Plants on Fractal Features of Soil Aggregates After Land Retired from Crop Cultivation in Slopes of Central Gansu

运用分形模型,研究陇中坡耕地及其退耕改种成苜蓿、侧柏、柠条、红柳、杏树后土壤团粒结构分形维数,并对分形维数与土壤理化性质之间的关系进行拟合。结果表明:各模式团粒结构分形维数介于2.014～2.153之间,且与>0.25mm粒径的团粒结构含量间呈极显著线性相关。退耕后,红柳、侧柏地>0.25mm的土壤团粒结构含量较其他模式显著增加,各类退耕地的土壤自然含水量、有机质、全氮含量明显高于坡耕地,但土壤团粒结构分形维数与有机质、全氮、全磷、有效磷、速效钾含量相关性不强。

By using fractal model,effects of different plants on fractal features of soil aggregates after land retired from crop cultivation,the relationship between fractal dimension and soil physical and chemical properties were investigated in slopes.Different plants investigated were alfalfa,arborvitae,Caragana,tamarisk and apricot.The results showed that the fractal dimension was ranged from 2.014 to 2.153,and it was significantly related with the content of aggregates 0.25 mm size class.As land retired from cultivation,the content of aggregates 0.25 mm size class in tamarisk and arborvitae field was higher than that of others.Soil moisture,organic matter and total N were increased compared with cultivated slopes,but the fractal dimension of soil aggregates was not significantly related with soil organic matter,total N,total P and available K.