耕作方式对耕层土壤结构性能及有机碳含量的影响

为了寻求能够提高土壤结构稳定性的耕作模式,在陇中黄土高原半干旱区连续7年的定位试验研究基础上,采用常规分析方法(湿筛法、重铬酸钾容量法、环刀法),研究了不同耕作方式对耕层土壤结构性能及有机碳含量的影响.结果表明:与传统耕作(T)相比,免耕无覆盖(NT)、传统耕作+秸秆还田(TS)和免耕+秸秆覆盖(NTS)3种保护性耕作方式均能不同程度地增加耕层土壤的有机碳和不同粒径水稳性团聚体的含量,其中免耕+秸秆覆盖(NTS)处理效果最佳.在0～10 cm土层中,NTS处理的土壤容重低、孔隙度大,土壤结构得到了较大改善.不同耕作方式下0～5 cm、5～10 cm和10～30 cm土层粒径1～0.5 mm水稳性团聚体的含量最高,粒径>0.25 mm水稳性团聚体含量与有机碳含量和孔隙度呈显著正相关,与容重呈显著负相关.

Effect of tillage practices on structural properties and content of organic carbon in tilth soil

To further explore tillage practices for improving soil structure, the effect of different tillage practices on the structure and organic carbon of tilth soils were investigated using routine method (Wet-sieving, Potassium dichromate volumetry and Core-cutting sampling). The 7-year research was conducted at an experimental station in the semiarid Loess Plateau zone in central Gansu Province. The conservative management practices of no-tillage (NT), conventional tillage with straw incorporation (TS) and no-tillage with straw mulch (NTS) increase soil organic C and water-stable soil aggregates contents, with the highest effect under NTS tillage. Soil bulk density decreases while soil porosity increases, greatly improving soil structure under NTS in the 0~10 cm soil layer. Content of soil water-stable aggregate (1~0.5 mm) is the highest in all 3 soil layers, 0~5 cm, 5~10 cm and 10~30 cm. Soil water-stable aggregate (>0.25 mm) has a significant positive correlation with soil organic C content and porosity, but is significantly negatively correlated with soil bulk density.