Aims

Land use change from native grasslands to arable lands globally impacts soil ecosystem functions, including the storage of soil organic carbon (SOC). Understanding the factors affecting SOC changes in topsoil and subsoil due to land use is crucial for effective mitigation strategies. We determined SOC storage and persistence as affected by land use change from native prairies to arable lands.

Methods

We examined SOC stocks, soil δ¹³C and ∆¹⁴C signatures, microbial communities (bacteria and fungi), and soil mineral characteristics under native prairies and long-term arable lands (i.e., > 40 years) down to 3 m in the U.S. Midwest.

Results

Native prairie soils had higher SOC stocks in the A horizon and 0–50 cm depth increment than arable soils. For both land use types, the δ¹³C and ∆¹⁴C values significantly decreased with depth, with the latter pointing towards highly stabilized SOC, especially in the B- and C-horizons. Analysis of the microbial communities indicated that the diversity of bacteria and fungi decreased with increasing soil depth. The content of oxalate soluble Al appeared to be the single most important predictor of SOC across horizons and land use types.

Conclusion

Our data suggest that most SOC gains and losses and transformation and translocation processes seem to be restricted to the uppermost 50 cm. Increasing SOC retention in the A and B horizons within the 0–50 cm depth would enhance organic material serving as substrate and nutrients for microbes and plants (A horizon) and facilitate long-term SOC storage in the subsoil (B horizon).

中文翻译：

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耕地和原生草原土地利用下三米土壤上部有机碳的储存和持久性

 目标

从原生草地到耕地的土地利用变化在全球范围内影响着土壤生态系统功能，包括土壤有机碳（SOC）的储存。了解因土地利用而影响表土和底土 SOC 变化的因素对于有效的缓解策略至关重要。我们确定了 SOC 存储和持久性受土地利用从原生草原到耕地变化的影响。

 方法

我们研究了原生草原和长期耕地（即耕地）下的 SOC 储量、土壤 δ ¹³ C 和 Δ ¹⁴ C 特征、微生物群落（细菌和真菌）以及土壤矿物特征。 ，> 40 年）在美国中西部降至 3 m。

 结果

原生草原土壤在 A 层和 0-50 厘米深度增量中的 SOC 储量高于耕地土壤。对于两种土地利用类型，δ ¹³ C 和 Δ ¹⁴ C 值随深度显着降低，后者指向高度稳定的 SOC，特别是在 B 和 C 地平线。微生物群落分析表明，细菌和真菌的多样性随着土壤深度的增加而减少。草酸盐可溶性铝的含量似乎是跨地层和土地利用类型的 SOC 的最重要的预测因子。

 结论

我们的数据表明，大多数 SOC 的增益和损失以及转化和易位过程似乎仅限于最上面 50 厘米。增加 0-50 厘米深度内 A 和 B 层中 SOC 的保留将增强作为微生物和植物（A 层）基质和养分的有机物质，并促进底土（B 层）中 SOC 的长期储存。