秸秆还田量对稻田土壤氧化还原状况的影响

Effect of the Amounts of Straw Returning on Soil Redox Status in Paddy Field

    摘要
  • 摘要:
    目的 为了探究不同秸秆还田量对土壤氧化还原状况的影响程度及其动态变化特征。
    方法 试验采用土柱培养模拟稻田秸秆还田，设置5个模拟还田量处理，即0%（秸秆不还田）、25%（还田量1500 kg hm−2）、50%（还田量3000 kg hm−2）、75%（还田量4500 kg hm−2）、100%（还田量6000 kg hm−2），测定培养第2、4、7、14、21、28天土壤pH、电导率（EC）、氧化还原电位（Eh）、还原性物质总量、活性还原物质、亚铁和亚锰含量，以及水体溶解氧（DO）的动态变化。
    结果 与秸秆不还田相比，土壤pH、Eh、水体DO随秸秆还田量的增加而逐步降低，降幅分别为2.1% ~ 2.7%、820% ~ 1910%、6.3% ~ 36.6%；土壤EC、还原物质总量、活性还原物质、亚铁、亚锰含量随秸秆还田量的增加而逐步增加，增幅分别为60.3% ~ 213.1%、99.7% ~ 176.2%、157.4% ~ 263.9%、236.4% ~ 380.0%、17.5% ~ 76.0%。培养28天内，各处理土壤pH、Eh、还原性物质积累量呈现先升高（14天内）后降低趋势，EC随着培养时间的增加，逐渐上升；水体DO除培养2天内表现出较高值，4 ~ 28天整体呈先升高后降低趋势。
    结论 在稻田土壤中，随秸秆还田量及秸秆还田时间增加，还原性物质积累量增大，土壤还原性环境增强；控制秸秆还田量小于3000 kg hm−2，或在秸秆快速腐解阶段，采取有效措施，可以改善土壤还原状态。

     

    Abstract:
    Objective Straw returning affects the redox status of paddy soil by affecting the redox potential (Eh) and the quality of reducing material. In order to explore the influence of different straw returning amounts on the soil redox status and dynamic change characteristics, the cultivation experiment was carried out under different levels of returning amounts.
    Method In this experiment, soil column culture was used to simulate the rice straw returning. Five treatments were set up to simulate straw returning, namely 0% (not returning), 25%(straw returning amounts of 1500 kg hm−2), 50% (straw returning amounts of 3000 kg hm−2), 75% (straw returning amounts of 4500 kg hm−2) and 100% (straw returning amounts of 6000 kg hm−2). The dynamic changes of soil pH, electrical conductivity (EC), Eh, total reducing material, active reducing material, ferrous and manganese contents, and dissolved oxygen (DO) in water were measured on the 2nd, 4th, 7th, 14th, 21st, and 28th days after cultivation, aiming to provide a theoretical basis for the treatment of soil reducing material.
    Result The results showed that soil pH, Eh and water DO decreased gradually with the increase of straw addition, with decreases of 2.1% - 2.7%, 820% - 1910% and 6.3% - 36.6%, respectively. The contents of soil EC, total reducing material, active reducing material, ferrous iron and manganese increased gradually with the increase of straw addition, with the increases of 60.3% - 213.1%, 99.7% - 176.2%, 157.4% - 263.9%, 236.4% - 380.0% and 17.5% - 76.0%, respectively. Within 28 days of incubation, the accumulation of soil pH, Eh and reducing material in each treatment first increased (within 14 days) and then decreased, and the EC gradually increased with the increase of incubation time. The DO in water showed a high value except for 2 days of culture, and the overall trend of increasing first and then decreasing from 4 to 28 days.
    Conclusion In paddy soil, with the increase of straw returning amounts and returning time, the accumulation of reducing material increases, the soil reducing environment are enhanced. As long as the amount of straw returning is less 3000 kg hm−2, or effective measures are taken in the rapid decomposition stage, the soil redox status can be improved.

     

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