耕作侵蚀对坡耕地土壤水稳定性团聚体和水分特征的影响

Tillage Erosion Influences on Soil Water-stable Aggregate and Moisture Properties on the Hillslope

通过模拟顺坡耕作（短期连续耕作45次）的方法研究模拟长期耕作对不同景观位置水稳定性团聚体和水分特征曲线分布等特征的影响。研究结果表明：与对照地相比（等高耕作1次）,模拟顺坡耕作样地（试验地）通过连续耕作45次后导致上坡和下坡土壤剖面深度发生显著变化（P〈0.05）,在上坡减小55.16%,然而下坡土壤剖面深度增加了40.62%;在中坡部位没有发生显著变化（P〉0.05）。与对照地相比,试验地平均质量直径（MWD）和几何平均直径（GMD）在上坡部位分别减少29.61%和35.63%,在下坡,MWD和GMD值分别显著增加78.23%和93.48%,然而在中坡,试验地MWD和GMD值仅分别增加13.51%和12.28%。试验地土壤水贮量在上坡部位比对照地降低了49.38%。对照地与试验地水分特征曲线分布显著变化主要发生在上坡和下坡部位。比较对照地,试验地在上坡的低吸力段（0-330kPa）土壤持水能力明显降低,而下坡的高吸力段（330-15 000kPa）土壤持水能力显著增大。这些变化主要是由于耕作侵蚀导致不同景观位置土壤再分布而产生的土壤空间变异性。

In this study,simulated tillage by hoeing was performed 45 times in a short time interval（3days）,to simulate the impact of long-term tillage on soil water-stable aggregates,and moisture properties at different slope positions.The results of the study showed that intensive tillage（consecutive 45 times tillage）results in a significant decrease by 55.16% at the upper slope positions and increased by 40.62% at down slope positions,but the middle slope position remained unchanged（P〉0.05）,compared with the control plot.In addition,the mean weight diameter（MWD）and geometric mean diameter（GMD）remarkably decreased by29.61% and 35.63%for the treatment plot at the upper slope positions,compared with those of the control plot.Significant increase of MWD and GMD values by 78.23% and 93.48% occurred at the lower slop positions,but there were slight increases by 13.51% and 12.28% at the middle slope positions as compared with control plot.A notable decrease by 49.38%in the water storage of soil profiles on the treatment plot was found at the upper slope positions compared with the control plot.At the upper and lower slop positions,a significant difference in the water characteristic curves was observed between the treatment plot and control plot.The moisture-holding capacity of the treatment plot in the low suction range（0-330kPa）of the upper slope positions were less than that of the control plot,yet there were remarkable increases in the high suction range（330-15 000kPa）of the lower slope positions.These results show that tillage erosion results in a large spatial variation in water-stable aggregates and moisture properties at the different landscape positions.