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.