Mollisols represent 29 % of agricultural land and they are considered to be one of the most fertile soils in the world. Here, we compare soil organic carbon (SOC) concentrations and pools of Mollisols for the globe, the USA and Poland, and review how differences are caused by climate, land use, and key environmental factors. Globally, the mean thickness of the A horizon in Mollisols is 50 cm. At 0–30 cm the mean SOC concentration is 2.3 %, SOC pool is 84 t ha, and clay content calculated at 0–50 cm soil depth is 21 %. Mollisols in the USA have an A horizon thickness of 36 cm and have a mean clay content of 27 % (0–50 cm). SOC concentrations are 2.0 and 1.7 % and SOC pools are 85 and 116 t ha at 0–30 and 0–50 cm soil depth, respectively. Mollisols in Poland have SOC concentrations of 1.8 and 1.5 % at 0–30 and 0–50 cm soil depth, respectively, and lower clay content (17 %) at 0–50 cm depth. The SOC pool at 0–30 cm depth is 74 t ha whereas it is 106 t ha at 0–50 cm. At the global scale, the highest SOC concentrations and pools are in Mollisols from Eastern Europe (including Ukraine and Western Russia) and Asia, while the lowest SOC pools are found in Mollisols from South America. The Mollisols in Western and Central Europe and North America have similar SOC pools, although Mollisols in North America have higher SOC concentrations and lower A horizon thickness. Globally, the mean pH value of Mollisols is 7.1, and the pH is slightly lower in Mollisols of the USA (6.9 ± 0.9). The SOC concentrations and pools are strongly and positively correlated with clay content. Soil moisture and temperature regimes determine SOC concentration and pools in Mollisols, and higher SOC concentrations and pools are in Mollisols with frigid and frigid-cryic soil temperature regimes as well as aquic, xeric, and aridic soil moisture regimes. Mollisols under grassland have the largest SOC pools compared to those cultivated or under forest. The important environmental factors on SOC concentrations and pools in Mollisols worldwide are soil texture, land use, and soil temperature regime.

中文翻译：

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世界软土中的有机碳——综述


软土占农业用地的 29%，被认为是世界上最肥沃的土壤之一。在这里，我们比较了全球、美国和波兰的土壤有机碳 (SOC) 浓度和软土池，并回顾了气候、土地利用和关键环境因素如何造成差异。全球范围内，莫利索尔斯 A 层的平均厚度为 50 厘米。 0–30 cm 的平均 SOC 浓度为 2.3%，SOC 库为 84 吨公顷，0–50 cm 土壤深度计算的粘土含量为 21%。美国的软土的 A 层厚度为 36 厘米，平均粘土含量为 27%（0-50 厘米）。土壤深度为 0-30 厘米和 0-50 厘米时，SOC 浓度分别为 2.0 和 1.7%，SOC 库分别为 85 和 116 吨公顷。波兰软土的 0-30 和 0-50 厘米土壤深度的 SOC 浓度分别为 1.8 和 1.5%，0-50 厘米深度的粘土含量较低 (17%)。 0-30 厘米深度的 SOC 池为 74 吨公顷，而 0-50 厘米深度为 106 吨公顷。在全球范围内，最高的 SOC 浓度和池位于东欧（包括乌克兰和俄罗斯西部）和亚洲的莫利土壤中，而最低的 SOC 池位于南美洲的莫利土壤中。西欧、中欧和北美的软土具有相似的 SOC 池，但北美的软土具有较高的 SOC 浓度和较低的 A 层厚度。全球范围内，Mollisols 的平均 pH 值为 7.1，美国 Mollisols 的 pH 值略低 (6.9 ± 0.9)。 SOC 浓度和池与粘土含量呈强烈正相关。 土壤湿度和温度状况决定了软土中的 SOC 浓度和库，并且在具有寒冷和寒冻土壤温度状况以及湿润、干旱和干旱土壤湿度状况的软土中，SOC 浓度和库较高。与耕地或森林下的软土相比，草地下的软土具有最大的 SOC 库。影响全球软土中 SOC 浓度和池的重要环境因素是土壤质地、土地利用和土壤温度状况。