麦稻轮作区周年耕作模式对作物产量和土壤特性的影响

Effect of Different Annual Tillage Patterns on Crop Yield and Soil Properties in Wheat-rice Rotation System

2004～2009年,在成都平原麦稻轮作区研究了不同周年耕作模式(周年翻耕无秸秆还田、小麦免耕稻草覆盖还田+水稻旋耕无秸秆还田、麦稻周年免耕秸秆全量还田、麦稻周年垄作免耕秸秆全量还田)对作物产量和土壤特性的影响。结果表明,不同模式间小麦产量差异较小,水稻产量差异较大;免旋结合稻草覆盖还田模式年际间水稻产量较其他模式稳定。麦稻关键生育阶段0～30 cm土层速效养分含量模式间差异较小;免旋结合稻草覆盖利于土壤表层有机质积累。周年免耕秸秆全量还田模式20 cm处紧实度降低,渗水速率增大,保水性能下降。研究结果说明,不同耕作模式下土壤养分供给能力不是影响作物产量的主要因素,因土壤物理性质变化导致水分下渗差异是水稻产量差异的重要原因,免旋结合稻草覆盖还田模式似乎更利于麦稻轮作田生产能力的稳定。

The wheat-rice rotation system was the major cropping system in south Asia and the Yangtze River Basin of China. From 2004 to 2009, the effect of different annual tillage patterns on crop yields and soil properties in a wheat-rice rotation system was studied in the Cheng- du Plain. The effects of four tillage patterns （annual plowing, no-tillage in wheat season with rice straw returning and rotary tillage in rice season, annual no-tillage with rice and wheat straw returning, annual ridge-no-tillage with rice and wheat straw returning）were tested in the experiment. The results showed that the difference in wheat yield among different treatments in the same year was not significant, but the difference in rice yield was obvious. The rice yield of the treatments with annual no-tillage and total straw mulching was lower than that of the control treatment with annual plowing and no straw zeturning, and decreased over the years. The rice yield of the treatments with no tillage in the wheat season and rice straw returning and rotary tillage in the rice season was higher and more stable than that of the other treatments. Because of the differenee in rice yield, the annual grain yield of the treatments with no tillage in the rice season and rotary tillage in the rice season remained similar over the years, while that of the control and annual no-tillage treatments showed a downward trend. During the main growth stages of wheat and rice in 2008 - 2009, available nutrient content in 0 - 30 cm soil layers was investigated; there was no obvious difference among different treatments. The combination of no-tillage and rotary tillage was favorable for the accumulation of organic matter. After 5 years, the organic matter content in 0 - 15 cm soil layers of the treatments with soil disturbance in the rice reason increased by 7.8 % compared with that in the control treatment. Total phosphorus, total potassium and available nutrient content did not obviously differ a- mong treatments in different soil layers. Compared with other treatments, the soil compactness of the treatments with annual no-tillage de- dined in 20 cm soil layers, and water transition rate in the rice season increased, especially during the green and tillering stage. These re-suhs suggest that the difference in water transition rate caused by the changes of soil physical properties is the primary cause of the difference in crop yields, and not any difference in soil fertility. The annual tillage pattern of no-tillage in the wheat season and rice straw returning and rotary tillage in the rice season helps keep production stable over years in a wheat-rice rotation system.