Sunlight and soil biota accelerate decomposition of crop residues in the Argentine Pampas
Sunlight and soil biota accelerate decomposition of crop residues in the Argentine Pampas
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DOI：
10.1016/j.agee.2022.107908
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发表时间：
2022-02-14
影响因子：
6.6
通讯作者：
Austin, Amy T.
中科院分区：
文献类型：
--
作者：
Araujo, Patricia, I;Grasso, Andres A.;Austin, Amy T.
在农业生态系统中保持土壤有机质的好处早已得到公认，尽管在控制作物残留物分解以及碳和养分循环的后果方面存在许多悬而未决的问题。阿根廷潘帕斯草原的大豆、向日葵、小麦和玉米密集种植农业的大规模推广，促使人们需要更广泛地了解这些控制措施。在现代免耕农业中，收获后的作物残留物可能会直立或长时间留在土壤表面;然而，阳光照射及其与土壤生物群的相互作用对作物残留物分解的影响尚未得到评估。我们建立了一个操纵性实验，大豆，向日葵，小麦和玉米作物残留物与处理的充分或减弱阳光照射和存在或不存在土壤生物群。在决定叶残体分解速率和质量损失方面，种间一致性显著，大豆>向日葵>小麦>玉米。在没有土壤生物的情况下，光照显著加速了叶片残体的分解，而在光照和无光照的情况下，土壤生物显著促进了叶片残体的分解。与此相反，茎残留物的分解是温和的，在所有条件下，分解的差异是由物种的身份。叶和茎残留物的表面积是最强的凋落物质量预测作物残留物分解的变化。我们的研究结果表明，阳光照射，休耕期的持续时间有或没有轮作或覆盖作物，以及与土壤生物群相互作用的作物残留物中的叶与茎的比例可能是决定这些密集种植的农业生态系统中的碳周转的基本要素。在本区域和全球可持续农业模式中纳入阳光照射的影响和作物残留物质量的未加探索的方面将具有重大价值。
The benefits of maintaining soil organic matter in agroecosystems have long been recognized, although there are many open questions with respect to the controls on crop residue decomposition and the consequences for carbon and nutrient cycling. The large extension of intensively cropped agriculture in the Argentine Pampas of soybean, sunflower, wheat, and maize motivates the need for a broader understanding of these controls. In modern no-till agriculture, post-harvest crop residues may remain upright as standing or on the soil surface for extended periods of time; nevertheless, the effects of sunlight exposure and its interaction with soil biota on decomposition of crop residues have not been evaluated. We established a manipulative experiment using soybean, sunflower, wheat and maize crop residues with treatments of full or attenuated sunlight exposure and presence or absence of soil biota. Species identity was significant in determining rates of leaf residue decomposition with mass loss of soybean > sunflower > wheat > maize. Sunlight exposure significantly accelerated decomposition of leaf resi-dues in the absence of soil biota, while soil biota significantly contributed to increased leaf residue decompo-sition with and without sunlight exposure. In contrast, stem residue decomposition was modest under all conditions and differences in decomposition were determined by species identity. Surface area for leaf and stem residues across species was the strongest litter quality predictor for the variation in crop residue decomposition. Our results suggest that sunlight exposure, duration of fallow period with or without rotation or cover crops, and the proportion of leaves vs. stems in crop residues interacting with soil biota may be fundamental elements in determining carbon turnover in these intensively cropped agroecosystems. There would be great value in incorporating the impacts of sunlight exposure and unexplored aspects of crop residue quality in models for sustainable agriculture in the region and globally.