Study of  tillage patterns suitable for soil physicochemical properties and crop yields in wheat/maize fields

【Objectives】Weibei Highland, part of Loess Plateau of China, is characterized by drought and rainless throughout the year, and the lack of natural rainwater is the main reason for crop cultivation. A long-term practice of applying single soil tillage treatment in this area causes soil compaction, poor ability of storing rainwater and providing nutrition, influencing the crop yields. In this study, the effects of different rotational tillage patterns on soil physicochemical properties and crop yields were investigated by conducting a long-term experiment in wheat/maize fields.【Methods】A four-year field experiment was conducted. Balance fertilization (N 150 kg, P2O5 120 kg and K2O 90 kg per hectare) was used as main plot and tillage systems including notillage/subsoiling rotation pattern(NT/SS), sub-soiling/ploughing rotation pattern (SS/P) and ploughing/notillage rotation pattern (P/NT) were used as subplots. Continuous no-tillage, sub-soiling and ploughing were used as controls. 【Results】 Compared with the continuous no-tillage, the soil bulk density of 0-40 cm soil layer under NT/SS, SS/P and P/NT was decreased by 4.50%, 6.45% and 3.57%, respectively. No difference was found between SS/P and continuous subsoiling. The SS/P decreased the soil bulk density by 1.78% compared with continuous ploughing. Compared with controls, organic matter content, total N, P, K contents, available N and K contents in 0-40 cm soil layer under SS/P are increased by 0.27%-15.60%, 3.14%-8.61%, 3.76%-24.32%, 15.62%-25.17%, 10.90%-14.43%, 8.61%-15.53%, respectively. The organic matter content, total N and available N content under P/NT are increased compared with continuous ploughing. The 0.25 mm water-stable aggregate contents of different tillage patterns in 0-40 cm soil depth are in order of continuous NT NT/SS continuous SS SS/P P/NT continuous ploughing. The water-stable aggregate contents under continuous no-tillage is significantly higher than all the other treatments (1.1-2.5 times). The four-year average yields of both winter wheat and spring maize in SS/P are higher than in NT/SS and P/NT, except the spring maize yield in 2009. Compared with continuous no-tillage, NT/SS increased crop yields by 12.05% (P0.05). Compared with continuous no-tillage, continuous sub-soiling and continuous ploughing treatments, the crop yields under the SS/P were significantly increased by 18.15%, 4.55% and 11.22%, respectively. The crop yields in SS/P are 5.44% and 14.57% higher than those in NT/SS and P/NT. The of P/NT is weak in the investigated soil physicochemical effects and the crop yields is decreased by 2.92% (P0.05). In general, NT/SS and SS/P systems had the better abilities of reducing soil bulk density, increasing soil water-stable aggregate, improving soil nutrients and promoting crop growth and development.【Conclusions】 In drought and rainless regions, the sub-soiling/ploughing rotation pattern could significantly improve the soil physicochemical properties, increase water-stable aggregates content, decrease soil bulk density, thereby stimulate the release of soil nutrition and improve crop yields. Therefore, no-tillage/sub-soiling rotation and sub-soiling/ploughing rotation patterns can be employed in Weibei Highland and similar areas for improving soil fertility and crop yield.