不同开垦年限黑土区坡耕地土壤团聚体稳定性与有机质关系

The relationships between aggregate water stability and soil organic matter of slope land with different reclamation years in black soil region

从不同开垦年限、土层和地形部位三个视角,应用慢速湿润法研究了东北黑土区坡耕地表层3~5 mm土壤团聚体稳定性与有机质的关系.结果表明：黑土开垦后,随着土壤有机质含量下降,土壤团聚体水稳性也明显降低;40 a以后,随着开垦时间的延长,两者的变化逐渐趋于稳定和平缓.MWDSW值、〉0.2 mm水稳定性土壤团聚体含量均与有机质含量显著正相关,相关系数分别是0.979和0.956（P〈0.05）.表层土壤团聚体水稳性高于次表层土壤,这与表层土壤有机质含量高于次表层有关.不同土层〉0.2、〉0.5 mm水稳性团聚体含量,MWD值与相应有机质含量相关系数分别为0.51、0.56、0.59（P〈0.05）,达到显著相关水平.不同地形部位表层土壤团聚体稳定性沿坡面呈波状起伏变化,变化规律不明显,主要是由于坡面不同地形部位土壤侵蚀、搬运和沉积作用强弱不同造成的.三种情况下,黑土表层土壤MWD值与有机质含量均显著相关.

The relationships between aggregate water stability（3～5 mm） and organic matter of top soil in slope land,black soil region of Northwest China,were studied by slow wetting method from the perspectives of different reclamation years,soil layers and landforms.The results showed that soil aggregate water stability decreases significantly with the declining of soil organic matter after reclamation,but 40 years later,the change trend of both becomes steady and gentle.The content of water-stable aggregate with 0.2 mm,and MWDsw value is notably related with the organic matter,and the correlative coefficients is 0.979 and 0.956（P0.05）.Water stability in the surface soil is much better than that of subsurface.It lies in the content of the organic matter in surface soil is higher than that in subsurface.The correlation coefficient of water-stable aggregates of 0.2 mm,0.5 mm and MWD value with organic matter is 0.59,0.51 and 0.56 respectively.The water-stable aggregate of surface soil in different landform presents a wavy change,and the change is not very regularly which is caused by the different power of soil erosion,movement,deposition in slope position.MWDsw value is notably related with the organic matter of subsurface soil under three conditions.