金沙江流域干旱河谷区坡耕地作物类型对耕作侵蚀的影响

为了研究干旱河谷区坡耕地农作物种植对耕作侵蚀的影响，在不同作物类型坡耕地(玉米地和荞麦地)上进行耕作试验，通过磁性示踪法测量坡耕地顺坡耕作的耕作位移距离，分析了不同作物类型下的耕作侵蚀速率特征。结果表明：(1)试验地类的耕作位移距离表现为玉米地<荞麦地<裸地(对照地)的变化趋势，荞麦地和玉米地的耕作位移距离均显著低于裸地(p<0.05),表明坡耕地种植玉米和荞麦可以显著减小坡耕地土壤耕作位移距离；(2)3种地类的耕作位移距离与坡度均呈显著正相关关系，玉米地和荞麦地的耕作位移距离系数k₂值和传输系数k₄值明显小于裸地，说明作物因素减小了耕作位移距离随坡度的增加幅度；(3)裸地的耕作侵蚀速率显著高于玉米地和荞麦地(p<0.01),分别是玉米地和荞麦地的1.99倍和1.88倍，说明坡地种植农作物可明显减小坡面耕作侵蚀。综上，种植农作物可有效减少坡耕地耕作侵蚀，研究成果丰富了对坡耕地作物根系防蚀特性的认识，也为完善耕作侵蚀模型奠定重要基础。

Effects of Crop Types on Tillage Erosion in the Dry Valleys of Jinsha River Basin

To study the effect of crop types on tillage erosion in dry valleys, tillage experiments on slope farmland with different crop types(bare field, corn field and buckwheat field)were implemented to measure the tillage displacement distance and tillage erosion rate with the magnetic tracer in the dry valley regions of Sichuan. The results showed that: the soil displacement distance of three farmlands decreased in the order: bare field>buckwheat field>corn field; soil translocation of corn field and buckwheat field was significantly less than that of bare field(p<0.05), and that of buckwheat land was slightly greater than that of corn land, which showed that crop factors could reduce the soil tillage displacement in sloping land; there was a significant positive correlation between tillage displacement and slope for the three land types, and tillage displacement coefficient k₂ and tillage transport coefficient k₄ for corn field and buckwheat field were significantly smaller than that of bare field, which indicated that crop factors reduced the increasing amplitude of tillage displacement with slope; tillage erosion rate of bare field was significantly greater than those of corn field and buckwheat within the range of measured slope field(p<0.01); Compared with corn field and buckwheat field, the mean tillage erosion rate for bare field increased by 1.99 times and 1.88 times, respectively, with no significant difference between corn field and buckwheat field(p>0.05). The above results indicate that the crop system reduced obviously tillage erosion for sloping farmland and weakened the influences of slope gradient on tillage erosion. The crop system is beneficial to the control of tillage erosion for slope farmland. The research results can enrich the understanding of anti-erosion characteristics of crop roots in sloping farmland and lay an important foundation for improving the tillage erosion model.