轮耕对土壤物理性状和冬小麦产量的影响

针对华北地区土壤连续单一耕作存在的主要问题，进行了土壤轮耕效应的研究。试验选择冬小麦夏玉米玉两熟区连续5 a免耕田，设置免耕、翻耕和旋耕3种轮耕处理（即免耕一免耕，免耕一翻耕和免耕一旋耕），冬小麦播种前进行耕作处理。研究结果表明：多年免耕后进行土壤耕作（翻耕、旋耕）可以显著降低土壤体积质量；旋耕显著降低0～10 cm土壤体积质量，翻耕则降低0～20 cm体积质量；随时间变化各处理土壤体积质量差异逐渐降低。翻耕、旋耕均显著增加了0～10 cm土壤总孔隙，同时翻耕显著增加了10～20 cm土壤总孔隙；翻耕、旋耕显著提高了5～10 cm毛管孔隙。0～10 cm土壤饱和导水率表现为旋耕＞翻耕＞免耕，翻耕、旋耕在5%水平上显著高于免耕；10～20、20～30 cm土层均表现为翻耕＞旋耕＞免耕，且10～20 cm翻耕5%水平上显著高于免耕；饱和导水率与体积质量呈显著线性负相关。翻耕、旋耕有效穗数与免耕相比分别提高了24.1%、22.3%；冬小麦的实际产量表现为：旋耕＞翻耕＞免耕，翻耕、旋耕分别比免耕增产11.8%、16.9%。总之，长期免耕后进行土壤耕作有利于改善土壤物理性状，提高作物产量。

Effects of rotational tillage on soil physical properties and winter wheat yield

Conservation tillage in Northern China was very common. However, many problems occurred for winter wheat fields with long-term no tillage, which was not favorable to winter wheat growth. In order to solve those problems, rotational tillage was introduced in this study. Rotational tillages were conducted in the winter wheat field with five years no-tillage under the wheat/corn double-cropping system. Treatments were NT (NT-NT), CT (NT-CT) and RT (NT-RT), respectively. The treatments were cultivated before sowing the winter wheat. Results showed as follows: Rotational tillages (CT, RT) after long-term no tillage significantly reduced soil bulk density; RT significantly reduced the soil bulk density at 0-10 cm layer While CT decreased at 0-20 cm soil layer. Differences of bulk density decreased with the growth of winter wheat. Rotational tillages significantly increased the soil total porosity at 0-10 cm layer, while CT significantly increased at the 10-20 cm soil layer. CT and RT increased soil capillary porosity at 5-10 cm layer. The soil saturated hydraulic conductivity at 0-10 cm soil layer was significantly higher for CT and RT than that for NT at 5% level, while that from the highest to the lowest were CT, RT, NT at 10-20 and 20-30 cm soil layers. And the soil saturated hydraulic conductivity of CT at 10-20 cm soil layer was significantly higher than NT at 5% level. The soil saturated hydraulic conductivity showed a significant negative linear correlation with soil bulk density. Rotational tillages significantly increased the effective panicle number and it was 24.1% higher in CT, 22.3% higher in RT compared with the NT. Yields from the highest to the lowest were RT, CT, NT. The yield of winter wheat was 11.8% higher in CT, 16.9% higher in RT compared with the NT treatment. After long-term no-tillage soil tillage can improve soil physical properties and increase crop yield.