Effects of Rotational Tillage on Soil Physicochemical Properties and Crop Yield in a Rice–Wheat Double Cropping Area

This paper aims to explore issues related to destruction of soil nutrients and structure in a rice-wheat double-cropping area caused by over-tillage prior to rice cultivation. A three-year cycle of rotation tillage pattern (RT), consisting of “no-tillage–no-tillage–plough”, with a straw-returning and direct rice-seeding technology, was designed and tested, and was compared with continuous no-tillage pattern (CN) and conventional ploughing & rotary tillage (PR). The soil rotation experiment in the rice-wheat double-cropping region is located on the southeastern coast of Shandong Province, with a warm, temperate, humid monsoon climate and paddy soil type. Comparison experiments were conducted on the three farming patterns over a period of 3 years, continuously measuring soil physical and chemical properties and crop yields. The results showed that under the same straw-returning conditions, RT significantly increased soil macroaggregates content and enhanced their stability within 0~30 cm (p < 0.05). RT significantly reduced the bulk density of 0~30 cm soil to below 1.5 g/cm3, which was beneficial to crop root growth (p < 0.05). Meanwhile, RT significantly increased the contents of soil organic carbon, total nitrogen, and available phosphorus, and the nutrients are evenly distributed in 0~30 cm layer(p < 0.05). Another result was that the RT significantly increased the rice panicle length, grains number per panicle, and thousand-grain weigh. The crop yield was not significantly different from that of PR, but significantly higher than that of CN (p < 0.05). At the same time, cultivation measures prior to rice cultivation had some after-effects on wheat; the RT significantly increased the average tillers, effective panicle number, effective panicle grain number, and thousand-seed weight of wheat; and the wheat yields were 10.5% and 13.3% higher than that of CN and PR, respectively. This study provides a theoretical reference for improving tillage patterns in rice-wheat double-cropping areas.