Effect Of Different Tillage Measures On Soil Aggregate Stability Of Dry Farmland Of The Loess Plateau

A 12-year local experiment of spring wheat-pea rotation system was conducted in rainfed farmlands of the Loess Plateau in central Gansu. For determining the distribution characteristics of soil organic carbon, total nitrogen and total phosphorus in soil aggregate, assessing the stability of soil aggregate under different tillage methods by dry sieving, wet sieving and LB method. The treatments consisted of four tillage practices ― conventional tillage without straw mulch(T), conventional tillage with straw incorporation(TS), no-tillage without straw mulching(NT) and no-tillage with straw mulching(NTS). The experimental set-up was a Randomized Complete Block design with three replications. The soil samples were taken at three different soil depths(0-5 cm, 5-10 cm and 10-30 cm) per plot. The aim of the study was to explore the optimum tillage method for agricultural sustainable development, environment-friendly, reducing soil and water erosion, improving the ability of soil carbon and nutrient sequestration. The main results have been listed as follows:1. Compared with conventional tillage, all three kinds of conservation tillage treatment can improve the content and stability of soil aggregate, taken together, NTS was the best tillage method.Compared with conventional tillage, NT, TS and NTS three tillage methods all can improve the content and stability of soil mechanism-s Tab aggregate and water-s Tab aggregate under various degree, reduce soil aggregate PAD, taken together, NTS was the best tillage method.2. Conservation tillage method can reduce water erosion in rainfed farmland, NTS method had the best effects.After all three wetting methods which were FW, SW, WS method, content of ≥0.25 mm water-s Tab aggregate and MWD in NTS method different soil layer showed the highest effects on gas and water explosion and reducing the impact of raindrop under two rotation sequences.3. Compared with conventional tillage, all three conservation tillage methods can improve the ability of soil carbon and nutrient sequestration, in particular, NTS treatment showed the best effect. Micro-aggregate had a better ability on soil carbon and nutrient sequestration than macro-aggregate.NTS treatment showed the best effects on improving content of SOC, TN, TP in different size classes aggregate in spring wheat field, TS method took second place. NTS and TS treatments showed the best effects on improving content of SOC, TN, TP in different size classes aggregate in pea field. <0.25 mm size class Micro-aggregate showed a better ability on soil organic carbon, total nitrogen and total phosphorus sequestration than ≥0.25 mm size classes macro-aggregate under two rotation sequences.