Abstract

Organic fertilization or conversion to grassland may increase soil organic carbon (SOC) and soil total nitrogen (STN). However, responses of net SOC and STN accumulation are sometimes inconsistent and little is known about temporal patterns when those strategies are stopped. We (a) assessed the effects of rye (Secale cereale L.) and hairy vetch (Vicia villosa Roth) cover crops (CCs) on SOC and STN during a 4-year “enriching” period (EP), and a following 2-year “depleting” period (DP); (b) compared these strategies with compost application and conversion to permanent fescue (Festuca arundinacea Schreb.); and (c) determined the responses of maize (Zea mays L.), soybean (Glycine max L. Merr.), and sunflower (Helianthus annuus L.) yields. Crop yield increased only in maize with compost and hairy vetch, which downsizes the role of these strategies to support productivity. SOC and STN increased with 4-year compost (+ 10.2 Mg C ha⁻¹; + 0.5 Mg N ha⁻¹), rye (+ 8.8 Mg C ha⁻¹; + 0.6 Mg N ha⁻¹), and hairy vetch (+ 6.9 Mg C ha⁻¹; + 0.6 Mg N ha⁻¹). Afterwards, SOC stock loss during 2-year DP tended to be higher than annual C input where there were CCs, and accounted for about 70% of annual C input where there was compost. High SOC loss highlights the weak effect of CCs for long-term SOC stabilization. Conversely, STN increased even during DP, which indicates a more lasting effect. Green manuring with CCs may be relevant for enhancing SOC and STN, although the beneficial effects are short-lived. Conversion to grassland remains the reference strategy.

Graphic abstract

中文翻译：

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覆盖农作物，堆肥并转化为草地，以增加集约化农业系统中的土壤碳和氮储量

摘要

有机肥或转化为草地可能会增加土壤有机碳（SOC）和土壤总氮（STN）。但是，净SOC和STN累积的响应有时会不一致，并且当停止这些策略时，对时间模式的了解很少。我们（a）评估了在为期4年的“浓缩”期（EP）中黑麦（Secale graine L.）和紫v（Vicia villosa Roth）覆盖作物（CCs）对SOC和STN的影响，以及随后的2-年度“消耗”期（DP）；（b）将这些策略与堆肥施用和转化为永久羊茅进行了比较（Festuca arundinacea Schreb。）；（c）确定玉米（Zea mays L.），大豆（Glycine max L. Merr。）和向日葵（向日葵（Helianthus annuus L.）产量。仅有堆肥和多毛紫菜的玉米单产提高，这降低了这些策略对提高生产力的作用。SOC和STN随着4年堆肥（+ 10.2 Mg C ha ^-1 ; + 0.5 Mg N ha ^-1），黑麦（+ 8.8 Mg C ha ^-1 ; + 0.6 Mg N ha ^-1）和有毛v子而增加（ + 6.9 Mg C ha ^-1 ; + 0.6 Mg N ha ^-1）。此后，2年DP期间SOC的库存损失往往高于有CC的年度C投入，占堆肥的年度C投入的约70％。高SOC损耗突出了CC对长期SOC稳定的弱作用。相反，即使在DP期间，STN也增加，这表明效果更持久。尽管有益效果是短暂的，但使用CC进行绿色施肥可能与提高SOC和STN有关。改用草地仍然是参考策略。

图形摘要