还田秸秆及其腐解产物的吸水能力研究

目的]研究水稻、小麦和油菜作物秸秆的腐解规律及其对秸秆吸水能力的影响,为农田秸秆资源有效利用和田间水分管理提供相应的理论依据。方法]采用尼龙网袋法进行试验研究。结果]在土壤水分饱和状态下,3种秸秆腐解速率均表现为前期快,后期缓慢的特点。培养结束(110d)时,水稻、小麦和油菜秸秆的累积腐解率分别为67.8%,55.5%和49.2%。光学显微镜结合红外光谱结果显示,与对照相比,水稻秸秆经过110d的腐解,其物质组成、化学结构和形貌特征均发生显著变化,小麦和油菜秸秆变化不明显。腐解0d时,水稻、小麦和油菜秸秆饱和吸水量依次分别为3.87,2.51,3.61g/g。随着秸秆组分、结构和形貌的变化,秸秆及其腐解产物饱和吸水量也有显著性差异。水稻秸秆在腐解15d时的饱和吸水量最大,为5.17g/g,之后其饱和吸水量逐渐下降并趋于稳定;小麦和油菜秸秆的饱和吸水量在腐解5d时达到最低值,分别为1.87,2.59g/g;之后其饱和吸水量逐渐增加。单位秸秆的吸水效果表明,3种作物秸秆在腐解初期的持水量最大,之后随着腐解时期的延长而有所降低。结论]还田作物秸秆的吸水能力受到还田秸秆质量和腐解时期的双重影响,故在开展秸秆还田(尤其翻压)时,应注意秸秆含水量,还田时期和田间水分管理,降低由秸秆吸水产生的负面效应。

Water Absorption Capacity of Straw Returns and Its Decomposing Matters

Objective] The objective of this study is to study the relationships between straw decomposition period and water absorption capacity of rice,wheat and rape straw in order to provide the theoretical basis for effective utilization of straw resources and field water management.Methods] The method of nylon net bag under moisture saturation incubation was used.Results] The decomposition rate of three crop straws was much faster at the early period than the following periods. The cumulative decomposing rates were 67.8%, 55.5% and 49.2% for rice, wheat and rape straw after 110 days, respectively. The light microscopy and infrared radiation(IR) analysis indicated that the composition, chemical structure and morphology of rice straws changed greatly compared to control treatment after 110 days incubation. The results of water absorption capacity showed that the saturated water of dried rice, wheat and rape straw were 3.87, 2.51 and 3.61 g/g, respectively. After 15 days incubation, the saturation water absorption of rice straw reached to the largest value of 5.17 g/g, then gradually decreased and tended to be stable. While the saturated water absorption of wheat and rape straw reached to the lowest, which were 1.87 and 2.59 g/g, respectively, after a 5 days incubation, and then increased gradually. The results of water absorption effects showed that the crop straw had the largest water retention capacity in the early decomposition period, and the water retention capacity decreased with the extension of the decomposing process. In brief, the water retention capacity of crop straw was influenced by both decomposition period and straw quality.Conclusion] In the implement of straw returning to filed, especially for straw incorporation, we should pay more attention to straw water content, returning period and field moisture, to reduce the negative effect caused by straw water absorption.