Management of rice straw in rice-soybean succession in tropical lowland

ABSTRACT This study aimed to analyze rice straw alternative managements to maximize the rice-soybean succession yield and to quantify their impacts on soil properties. The experiment was set up in a completely randomized design with six replicates. Nine rice straw managements were evaluated: straw burning (M1), straw harvesting (M2), straw incorporation with disc harrow and two passes (M3) or three passes (M4) of leveling disc harrow, straw incorporation with knife-roller and soybean no-tillage (M5), straw incorporation with knife-roller and two passes (M6) or three passes (M7) of leveling disc harrow, straw incorporation with two passes of knife-roller and two passes (M8) or three passes (M9) of leveling disc harrow. Straw incorporation by knife-roller provided the lowest soil organic matter (SOM) contents due to slow mineralization of fresh straw incorporated shallow into the soil, although SOM increased in the surface layer related to the initial content. Rice-soybean succession yield was more affected by the physical than by the soil chemical properties. The straw incorporation with one pass of knife-roller and two passes of leveling disc harrow (M6) can replace the straw burning, without affecting the rice-soybean succession yield and soil physical quality, with a reduction in machinery operations, allowing early soil tillage.

摘要：本研究旨在分析水稻秸秆的替代管理方案，以最大化稻豆连作产量，并量化其对土壤性状的影响。实验采用完全随机设计，设置6次重复。共评估9种水稻秸秆管理方案：秸秆焚烧（M1）、秸秆回收（M2）、采用圆盘耙结合2遍圆盘平地耙作业（M3）或3遍圆盘平地耙作业（M4）的秸秆还田、采用刀辊式还田机结合大豆免耕（M5）、采用刀辊式还田机结合2遍圆盘平地耙作业（M6）或3遍圆盘平地耙作业（M7）、采用2遍刀辊式还田机结合2遍（M8）或3遍圆盘平地耙作业（M9）的秸秆还田。由于鲜秸秆浅施还田后矿化速率较慢，刀辊式还田处理的土壤有机质（soil organic matter, SOM）含量最低；不过表层土壤有机质含量较初始水平有所提升。稻豆连作产量受土壤物理性状的影响大于化学性状。采用1遍刀辊式还田机结合2遍圆盘平地耙作业的M6处理可替代秸秆焚烧，既不会对稻豆连作产量及土壤物理质量造成负面影响，还能减少农机作业次数，实现土壤耕作的提早开展。