Soil macroaggregation drives sequestration of organic carbon and nitrogen with three-year grass-clover leys in arable rotations.
Soil macroaggregation drives sequestration of organic carbon and nitrogen with three-year grass-clover leys in arable rotations.
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土壤宏观团聚驱动三年草三叶草地在耕地轮作中封存有机碳和氮。
DOI：
10.1016/j.scitotenv.2022.158358
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发表时间：
2022
期刊：
影响因子：
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通讯作者：
Guest EJ
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作者：
Guest EJ
传统的耕地种植与一年生作物建立犁和耙降解较大的土壤团聚体，有助于储存土壤有机碳（SOC）。迫切需要增加土壤有机碳含量的耕地，以改善其功能和封存大气中的CO2，激发了研究的影响，重新引入leys到长期的常规耕地。然而，短期leys对总SOC积累的影响一直是模棱两可的。由于土壤团聚体可能是重要的碳储存，我们研究了三年后，形成土的土壤中，土壤的水稳性团聚体的浓度和库存的SOC，氮和它们的分布的影响。这些值是以树篱边缘以下的土壤为基准的。土壤有机碳储量（0-7 cm深度）从20.3 Mg ha− 1增加到22.6 Mg ha− 1，相比之下，绿篱中的土壤有机碳储量为30 Mg ha− 1，但这2.3 Mg ha− 1（或0.77 Mg C ha− 1 yr −1）的差异并不显著。然而，大团聚体（> 2000 μm）的比例在犁地到犁地的转换中增加了5.4倍，恢复到与树篱土壤相似的丰度，推动大团聚体中SOC和氮的几乎平行增加（分别为5.1和5.7倍）。大团聚体中储存的总有机碳（0-7 cm深度）在阿拉伯到土地转换中从2.0增加到9.6 Mg ha− 1，与绿篱下的12.1 Mg ha− 1不再有显著差异。因此，大团聚体中的碳积累速度比大体积土壤快三倍，为2.53 Mg C ha− 1 yr −1。这些研究结果强调了监测大团聚体结合SOC的价值，作为土壤质量变化的关键早期指标，以应对田间管理的变化，以及leys在土壤团聚，碳积累和土壤功能方面的好处，为鼓励在耕地轮作中更广泛地使用leys的财政激励措施提供了理由。
Conventional arable cropping with annual crops established by ploughing and harrowing degrades larger soil aggregates that contribute to storing soil organic carbon (SOC). The urgent need to increase SOC content of arable soils to improve their functioning and sequester atmospheric CO2has motivated studies into the effects of reintroducing leys into long-term conventional arable fields. However, effects of short-term leys on total SOC accumulation have been equivocal. As soil aggregation may be important for carbon storage, we investigated the effects of arable-to-ley conversion on cambisol soil after three years of ley, on concentrations and stocks of SOC, nitrogen and their distributions in different sized water-stable aggregates. These values were benchmarked against soil from beneath hedgerow margins. SOC stocks (0–7 cm depth) rose from 20.3 to 22.6 Mg ha−1in the arable-to-ley conversion, compared to 30 Mg ha−1in hedgerows, but this 2.3 Mg ha−1difference (or 0.77 Mg C ha−1yr−1) was not significant). However, the proportion of large macroaggregates (> 2000 μm) increased 5.4-fold in the arable-to-ley conversion, recovering to similar abundance as hedgerow soils, driving near parallel increases in SOC and nitrogen within large macroaggregates (5.1 and 5.7-fold respectively). The total SOC (0–7 cm depth) stored in large macroaggregates increased from 2.0 to 9.6 Mg ha−1in the arable-to-ley conversion, which no longer differed significantly from the 12.1 Mg ha−1under hedgerows. The carbon therefore accumulated three times faster, at 2.53 Mg C ha−1yr−1, in the large macroaggregates compared to the bulk soil. These findings highlight the value of monitoring large macroaggregate-bound SOC as a key early indicator of shifts in soil quality in response to change in field management, and the benefits of leys in soil aggregation, carbon accumulation, and soil functioning, providing justification for fiscal incentives that encourage wider use of leys in arable rotations.