西南黄壤坡耕地保护性耕作的土壤结构效应

设置两种保护性耕作措施,通过6a持续试验,研究了保护性耕作措施对黄壤结构性状的影响,为西南黄壤地区保护性耕作技术应用与发展提供理论依据。[方法]分别用环刀法、干湿筛法测定土壤容重和土壤团聚体组成,土壤机械组成采用MS2000激光粒度分析仪测定,并计算出土壤孔隙度和团聚体破坏率。 [结果]结果表明：(1)垄播沟覆轮耕与免耕秸秆覆盖两种保护性耕作措施均可降低黄壤容重,增加土壤孔隙,且此作用是由表及里的渐进过程,垄播沟覆措施的土壤容重优化作用要优于免耕覆盖,而免耕覆盖对较深层次土壤孔隙状况优化效果更显著。(2)保护性耕作可提高0～20 cm土壤＞0.25mm干筛团聚体含量,水稳性团聚体含量处理之间差异不显著,但0～20cm层含量略大于20～40cm层。(3)保护性耕作可提高土壤团聚体稳定性,降低团聚体破坏率,免耕覆盖措施对提高土壤团聚体稳定性具有更加显著的效果。[结论]该试验证明了保护性耕作对黄壤土容重、孔隙、团聚体等结构性状有一定的改善作用,这种改善作用是一个非常漫长的由表及里的渐进过程,为西南黄壤地区保护性耕作技术应用与发展奠定了坚实的基础。

Soil Structure Effect of Conservation Tillage in Yellow Soil Slope Cropland in Southwest China

Effect of conservation tillage on soil structure of yellow soil was explored through setting two kinds of conservation tillage by continuous testing through 6 years to provide a theoretical basis for the conservation tillage technology application and development in yellow soil area in South China. [Method] Soil bulk density and soil aggregates were determined by ring-knife method and dry-wet sieve method. Soil mechanical composition was determined by MS2000 laser particle size analyzer, and soil porosity and aggregate failure rate were calculated. [Result]The results indicated that soil bulk density decreased and soil porosity increased in two kinds of conservation tillage of no-tillage with mulch(NTS) and sowed on ridges with mulch in furrows(LS). LS optimize the role of soil bulk density superior to NTS, and NTS optimized soil pore conditions effect is more pronounced for deeper levels of soil. The optimization process of conservation tillage on soil bulk density and soil porosity were gradually from surface to interior. Conservation tillage can increase the 0-20 cm layer of soil >0.25mm aggregate content. When it came to water stable aggregate content there"s no obvious difference between the three treatments but the content of 0-20cm layer of soil is slightly larger than 20-40cm layer. Conservation tillage can increase soil aggregate stability and reduce aggregate destruction and NTS have more significant effect to improve the stability of soil aggregates. [Conclusion] The experiment proved that the conservation tillage had some effect on the soil bulk density, porosity, aggregates and other structural traits of the yellow soil. The improvement was a very long process from the surface to the surface, which was the conservation tillage technology in the yellow soil region Application and development has laid a solid foundation.