机械压实对黑土区耕作土壤团聚体特征的影响

Effect of Heavy Machinery Operation on Soil Aggregates Character in Phaeozem Region

以东北典型黑土区耕地土壤为研究对象,通过对不同机械碾压处理后土壤干筛团聚体和水稳性团聚体粒级分布、破坏率PAD0.25、分形维数D、平均重量直径MWD、平均重量比表面积MWSSA等特征指标的测定和分析,研究了模拟机械作业过程中积累压实对土壤团聚体特征的影响。结果表明:黑土耕作区0～30cm范围内干筛团聚体组成以>2mm粒级的团聚体为主,机械压实后其组成特征表现出均质的趋向;水稳性团聚体构成则以<0.25mm为主,随着碾压次数的增加,对水稳性团聚体的影响也逐渐从大粒级过渡到小粒级;机械压实可以促进团聚体的团聚作用,增强土壤的机械稳定性和水稳定性,但稳定性会随着碾压次数的增加而削弱。MWSSA与其他常用团聚体特征值PA0.25、MWD、D、PAD0.25的线性关系达到了极显著水平,说明MWSSA同样可以作为分析和研究土壤团聚体特征的有效指标。

The influence of machinery compaction on the features of soil aggregates were revealed by measuring and analyzing the soil dry and water-stable aggregate distribution, percentage of aggregate disruption-PAD0.25,fractal dimension-D, mean weight diameter-MWD, mean weight soil specific area-MWSSA after machinery moving in typical black soil region of Northeast China. The results suggested that： soil dry aggregates over 2mm were predominate and showed homogeneous trend in the cropping region of 0-50cm depth, water-stable aggregates smaller than 0.25mm were the most and the disturbance effect on them was form greater to smaller diameter class. Machinery compaction could promote aggregation and enhance the mechanical stability and water stability, however the stability would be weakened with the tractor passes increasing. MWSSA had extremely significant linear relationship with PA0.25,MWD, D,PAD0.25, so MWSSA was also an effective index to analyze and study on soil aggregates.