Long-term straw return increases fungal residual contribution to soil microaggregate nitrogen pool: An eco-enzymatic stoichiometric study

IF 6.1 1区 农林科学 Q1 SOIL SCIENCE Soil & Tillage Research Pub Date : 2024-08-29 DOI:10.1016/j.still.2024.106278
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Abstract

Straw return is a widespread agricultural practice for improving cropland nitrogen (N) stocks. However, the contribution of microbial N to the soil aggregate N pool and the underlying microbial metabolic regulation mechanisms remain uncertain. This study was based on a 13-year field experiment with rice (Oryza sativa L.) and wheat (Triticum aestivum L.) rotation, using only a chemical fertilizer alone (CF) as the control. We analyzed the effects of the chemical fertilizer combined with (CS, 9500 kg ha−1 y−1) and wheat (4000 kg ha−1 y−1) straw on microbial derived-N, microbial carbon (C) and N limitations. We also assessed microbial N use efficiency (NUE) in various aggregates of ferric lixisols (020 cm). Rotary tillage reached a depth of 20 cm. The CS significantly increased microbial-derived N concentrations in soil aggregates and enhanced the contribution of fungal residual N to the N pool in aggregates < 0.25 mm, but did not affect those > 0.25 mm. Conversely, the bacterial contribution to the N pool was not affected by CS. Meanwhile, CS significantly increased the soil organic C and microbial biomass in the aggregates. The results of our eco-enzymatic stoichiometric model revealed that the CS significantly alleviated microbial C limitations and increased microbial NUE in soil aggregates. Structural equation modeling further revealed that the microbial biomass and soil organic C contents are key drivers of the microbial C limitation. The increased contribution of fungal residual N to the N pools in < aggregates 0.25 mm was attributed to improved microbial NUE resulting from the straw, without altering net N mineralization rates or β-1,4-N-acetylglucosidase activity. Our findings suggest that straw return promotes microbial-derived N production and sequestration by alleviating microbial C limitation. The strategies governing these microbial-derived N responses in aggregates to straw return might vary. This might be valuable for designing cropland management practices to improve N storage.

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长期秸秆还田增加了真菌对土壤微团聚氮库的残留贡献:生态酶化学计量学研究
秸秆还田是改善耕地氮(N)储量的一种普遍农业做法。然而,微生物氮对土壤总氮库的贡献以及潜在的微生物代谢调节机制仍不确定。本研究基于一项为期 13 年的水稻(Oryza sativa L.)和小麦(Triticum aestivum L.)轮作田间试验,仅以单独施用化肥(CF)作为对照。我们分析了化肥与(CS,9500 kg ha-1 y-1)和小麦(4000 kg ha-1 y-1)秸秆相结合对微生物衍生-N、微生物碳(C)和氮限制的影响。我们还评估了铁质lixisols(0-20 厘米)中各种聚集体的微生物氮利用效率(NUE)。旋耕深度为 20 厘米。CS明显增加了土壤团聚体中微生物衍生的氮浓度,提高了真菌残余氮对0.25毫米及以上团聚体中氮库的贡献,但对0.25毫米及以上团聚体没有影响。相反,细菌对氮库的贡献不受 CS 的影响。同时,CS 能明显增加团聚体中的土壤有机碳和微生物生物量。我们的生态酶化学计量模型的结果表明,CS 能明显缓解土壤团聚体中微生物的 C 限制,增加微生物的 NUE。结构方程模型进一步显示,微生物生物量和土壤有机碳含量是微生物碳限制的主要驱动因素。真菌残留氮对 0.25 毫米秸秆团聚体中氮库的贡献增加归因于秸秆改善了微生物的氮利用效率,而没有改变净氮矿化率或β-1,4-N-乙酰葡萄糖苷酶活性。我们的研究结果表明,秸秆还田通过缓解微生物的碳限制,促进了微生物衍生氮的产生和固碳。在秸秆还田的情况下,聚合体中微生物源性氮的反应策略可能会有所不同。这对于设计耕地管理措施以改善氮储存可能很有价值。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Soil & Tillage Research
Soil & Tillage Research 农林科学-土壤科学
CiteScore
13.00
自引率
6.20%
发文量
266
审稿时长
5 months
期刊介绍: Soil & Tillage Research examines the physical, chemical and biological changes in the soil caused by tillage and field traffic. Manuscripts will be considered on aspects of soil science, physics, technology, mechanization and applied engineering for a sustainable balance among productivity, environmental quality and profitability. The following are examples of suitable topics within the scope of the journal of Soil and Tillage Research: The agricultural and biosystems engineering associated with tillage (including no-tillage, reduced-tillage and direct drilling), irrigation and drainage, crops and crop rotations, fertilization, rehabilitation of mine spoils and processes used to modify soils. Soil change effects on establishment and yield of crops, growth of plants and roots, structure and erosion of soil, cycling of carbon and nutrients, greenhouse gas emissions, leaching, runoff and other processes that affect environmental quality. Characterization or modeling of tillage and field traffic responses, soil, climate, or topographic effects, soil deformation processes, tillage tools, traction devices, energy requirements, economics, surface and subsurface water quality effects, tillage effects on weed, pest and disease control, and their interactions.
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