Abstract. Increasing soil organic carbon (SOC) in agricultural soils is nowadays receiving growing attention also due to the COP21 initiative of “4 per 1000”. In this study, the effect of five decades of different residue management (residue removal, residue incorporation, and residue incorporation + poultry manure) was investigated on SOC stock and related to the 4 per 1000 and C saturation concepts. Preliminary results showed that higher 0–60 cm SOC stock was found after 54 years of the experiment when residues were incorporated into the soil compared to residue removal (75.0 vs 69.0 t ha⁻¹) while poultry manure had a negligible effect. Comparing the 0–30 cm SOC stock with pre-existent data series, a general decreasing trend was observed from the start of the experiment in 1966 up to 1986, being greater in residual removal (−8.6 t ha⁻¹) than residual incorporation (−4.8 t ha⁻¹, irrespective of poultry manure addition). In 2020, the difference between the above-mentioned systems was 4.1 t ha⁻¹ corresponding to a 2.2 ‰ which is lower than what was suggested by the 4 per 1000 initiative. This SOC stock attributed to residue retention arose in response to 141 t C ha⁻¹ residue resulting in a 0.1 % yearly conversion rate that is sensibly lower than what is generally reported in the literature. Therefore, an alternative use (e.g., bioenergy production) of at least part of crop residues is conceivable in temperate climate for a more efficient C cycle. The studied soil was demonstrated also to be far from C saturation, being in the 30−47 % degree of saturation range. Therefore, specific studies on how both organic and inorganic (i.e., carbonates) C fractions related to different soil aggregates and aggregate mineralization are namely requested.

中文翻译：

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温带气候下五年不同作物残留物管理后的碳动态

摘要。由于 COP21 提出的“千分之四”倡议，如今增加农业土壤中的土壤有机碳 (SOC) 也受到越来越多的关注。在这项研究中，研究了五年不同残留物管理（残留物去除、残留物掺入和残留物掺入 + 家禽粪便）对 SOC 储量的影响，并与千分之四和 C 饱和度概念相关。初步结果表明，与去除残留物相比，在 54 年的实验后发现残留物被纳入土壤时，0–60 cm SOC 储量更高（75.0 对 69.0 t ha ^-1) 而家禽粪便的影响可以忽略不计。将 0–30 cm SOC 储量与先前存在的数据系列进行比较，从 1966 年实验开始到 1986 年，观察到总体下降趋势，残留去除 (-8.6 t ha ^-1 ) 大于残留掺入 ( −4.8 t ha ⁻¹，与家禽粪便添加无关）。2020 年，上述系统之间的差异为 4.1 t ha ⁻¹，相当于 2.2 ‰，低于每 1000 人 4 个倡议建议的水平。这种归因于残留物保留的 SOC 存量响应于 141 t C ha ⁻¹残留物导致 0.1% 的年转化率明显低于文献中通常报道的转化率。因此，为了更有效的碳循环，可以设想在温带气候下至少部分作物残余物的替代用途（例如，生物能源生产）。所研究的土壤也被证明远离 C 饱和度，处于 30-47% 的饱和度范围内。因此，需要具体研究有机和无机（即碳酸盐）碳组分如何与不同的土壤团聚体和团聚体矿化相关。