Journal of Integrative Agriculture ›› 2021, Vol. 20 ›› Issue (1): 248-259.DOI: 10.1016/S2095-3119(20)63238-5

所属专题： 农业生态环境-氮素合辑Agro-ecosystem & Environment—Nitrogen

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  • 收稿日期:2019-12-10 出版日期:2021-01-01 发布日期:2020-12-13

Nitrogen release and re-adsorption dynamics on crop straw residue during straw decomposition in an Alfisol

LI Ji-fu, ZHONG Fang-fang   

  1. Engineering Research Center of Ecology and Agricultural Use of Wetland, Ministry of Education/College of Agriculture, Yangtze University, Jingzhou 434025, P.R.China
  • Received:2019-12-10 Online:2021-01-01 Published:2020-12-13
  • Contact: Correspondence LI Ji-fu, Tel: +86-716-8066314, E-mail: jifuli@yangtzeu.edu.cn
  • Supported by:
    This work was supported by the National Key Research & Development Program of China (2018YFD0200900), the Young and Middle-Aged Talents Project of Hubei Provincial Department of Education, China (Q20181303), and the Open Fund of Key Laboratory of Fertilizer Utilization, Ministry of Agriculture and Rural Affairs, China (KLFAW201901). We thank LetPub (www.letpub.com) for its linguistic assistance during the preparation of this manuscript.

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摘要：

秸秆还田不仅提高土壤氮素供应和保持能力，还可减少农业有机废物量和防止空气污染。明确田间作物秸秆腐解与氮素释放、再吸附过程的关系，有助于加强作物生长期氮肥科学施用和管理。本研究以水稻、小麦和油菜秸秆为研究对象，采用尼龙网袋法在稻田进行腐解试验。结果表明，在腐解初期，3种作物秸秆的腐解速率均较快；后期则较为稳定，3种作物秸秆的腐解速率无显著性差异。腐解120 d后，水稻、小麦和油菜秸秆的累积腐解率分别为72.9%、56.2%和66.9%；秸秆氮素累积释放率则依次分别达到52.0%、54.4%和54.9%。水稻、小麦和油菜秸秆腐解产物的Zeta电位和比表面积随腐解时间的延长而逐渐增加。不同腐解时期，水稻秸秆的吸水能力变化明显，其饱和吸水量在腐解30 d时达到最大值（4.17 g g-1），之后略有下降。小麦和油菜秸秆的饱和水量在腐解30 d时均达到最低值，之后逐渐增加并保持动态平衡。综合研究表明，作物秸秆及其腐解物在释放氮素的同时可从周围溶液中重新吸附NH4+离子，其再吸附能力受腐解时期和外源NH4+浓度的双重影响，且通过物理吸附、化学吸附、离子交换和秸秆保水4种方式共同作用，与作物秸秆种类无关。因此，在农田进行秸秆还田配施氮肥过程中，要考虑土壤含水量差异的潜在负面影响，如秸秆投入过多或者淹水都会增加土壤供氮水平，可适当减少氮肥用量。


Abstract:

Returning crop straw to the field not only improves the nitrogen (N) supplying capacity and N retention of soil but also decreases the amount of rural organic waste and prevents air pollution.  Therefore, understanding the mechanisms of the N release and re-adsorption dynamics on crop straw residue during straw decomposition in agricultural soil is important, and this understanding can help us strengthen N fertilizer management during the crop growth period.  An on-farm incubation experiment was conducted in the Jianghan Plain in Central China under flooded conditions using the nylon mesh bag method.  Results showed that the decomposition rate of crop straw was much faster at the beginning of the incubation stage, whereas it was steady during the later stage with no observed differences among the three types of crop straw.  After 120 d of incubation, the cumulative decomposition proportion of rice straw, wheat straw and rape straw was 72.9, 56.2, and 66.9%, respectively.  The proportion of N that released from the three crop straws was 52.0, 54.4 and 54.9%, respectively.  The zeta potentials and Brunauer, Emmett and Teller (BET) surface area of the rice, wheat and rape straw residues increased gradually as the decomposition period progressed.  The water adsorption capacity of the rice straw was significantly affected during the decomposition period.  The saturated water adsorption capacity of rice straw was the highest at 30 d of decomposition (4.17 g g–1) and then decreased slightly.  The saturated water adsorption of wheat and rape straws reached the lowest value at 30 d and then gradually increased and became stable.  All the results demonstrated that crop straw and straw residue can re-adsorb NH4+ ions from the surrounding solution.  The re-adsorption was affected by the decomposition period and concentration of exogenous NH4+ and was independent of the crop species via the combined efforts of physical and chemical adsorption, ion exchange and water retention on residue surfaces.  Future studies will focus on straw returning and N fertilizer application at different levels of moisture content of the soil reduce potential negative effects such as water-logging and excess N caused by the straw substrate.
 

Key words: adsorption ,  decomposition ,  nitrogen (N) ,  Alfisol ,  straw substrate