1st International Conference of Soil and Agriculture:
TOWARDS SOIL SUSTAINABILITY
11–13 June 2024 • Lublin–Nałęczów, Poland

https://doi.org/10.24326/ICSA1.PP.20
Published online: 4 October 2024

Organic carbon in Mollisols of the world – a review
Beata Łabaz¹*, Alfred E. Hartemink², Yakun Zhang², Annalisa Stevenson², Cezary Kabała¹

¹ Institute of Soil Science, Plant Nutrition and Environmental Protection, Wroclaw University of Environmental and Life Sciences, Grunwaldzka 53, 55-093 Wrocław, Poland
² FD Hole Soils Lab, Department of Soil Science, University of Wisconsin-Madison, 1525 Observatory Drive, Madison, WI 53706, USA
* Corresponding author:

Abstract
Mollisols are considered one of the most fertile soils in the world. The high yields of cereals, root crops and vegetables have caused them to be a so-called symbol of soil fertility or the granary of the world. This SOC-rich and fertile soils are currently threatened with severe degradation or even complete disappearance in many countries worldwide. This study reviews scientific literature that included SOC data in Mollisols. The three objectives were to review: (i) the diversity of Mollisols in terms of A horizon thickness, soil pH, clay content, SOC concentrations and SOC pools; (ii) the influence of climatic factors (soil temperature and moisture regimes), land use (cropland, grassland, forest) and soil texture on the SOC concentration and SOC pools; and (iii) to determine key environmental factors that are responsible for SOC storage in Mollisols. The mean thickness of the humus A horizon in Mollisols worldwide is 50 cm, the mean SOC concentration in the 0–30 cm soil layer is 2.3% and 1.9% in the 0–50 cm layer. SOC pool is 84 and 132 t/ha for the 0–30 and 0–50 cm layer, respectively, and the mean clay fraction is 21% in the 0–50 cm soil layer. Mollisols in Poland have the same mean A horizon thickness as the global mean thickness, 50 cm, but are distinguished by a lower SOC concentration: 1.8% and 1.5% in the 0–30 and 0–50 cm horizons respectively, the lower than global mean SOC pool of 74 and 106 t/ha in the 0–30 and 0–50 cm horizons, and the lower mean clay fraction content, 17%. Globally, the highest SOC concentrations and resources are found in the Mollisols of Eastern Europe (including Ukraine and the European part of Russia) and Asia, while the lowest SOC pools are recorded in South American soils. Mollisols in Western and Central Europe and North America are similar in terms of SOC resources. Soil moisture and temperature regimes determine SOC accumulation in Mollisols. The highest SOC accumulation occurs in areas with an aquic moisture regime, as well as with an aridic moisture regime and a simultaneous frigid temperature regime. Important environmental factors that influence SOC accumulation in Mollisols are soil texture and soil temperature regimes and A horizon thickness.

Keywords: Mollisols, SOC concentrations, SOC pools, A horizon thickness, distribution of Mollisols

How to cite
Łabaz B., Hartemink A.E., Zhang Y., Stevenson A., Kabała C., 2024. Organic carbon in Mollisols of the world – a review. 1st International Conference of Soil and Agriculture: Towards Soil Sustainability. https://doi.org/10.24326/ICSA1.PP.20