Effects of climate and clay content on soil organic carbon in the Eurasian steppe
2016
Kanda, T. (University of Tsukuba, Tsukuba, Ibaraki (Japan). Graduate school of Life and Environmental Sciences) | Tamura, K. | Asano, M. | Wuyunna | Tsunekawa, A. | Nakamura, T.
This study involved a large soil survey of the entire Eurasian steppe and analysis of physico-chemical properties in A horizons to examine factors that control soil organic carbon (SOC) content. The relationship between Eurasian steppe SOC and clay content was characterized and compared with that of grassland regions in different climates. There were 43 Eurasian steppe sites studied between Ukraine and Inner Mongolia with mean annual temperatures of - 4.5-8.2 degC and mean annual precipitation of 118-621 mm. The SOC and clay content of the A horizons were 4.9-65.7 g/kg and 6.6%-56.0%, respectively. Simple linear regression analyses indicated that mean annual precipitation, aridity index, and clay content each have a significant linear correlation with the SOC content (r = 0.73, 0.76, and 0.71, respectively, p < 0.01). Clay content was also correlated with the mean annual precipitation (r = 0.62, p < 0.01). Comparison of the SOC and clay content relationship among grassland regions resulted in a higher SOC content of the Eurasian steppe than the semiarid-arid grassland in South America. The increased mean annual precipitation in the Eurasian steppe coincides with the increased SOC content in the A horizon because the carbon input from vegetation and clay content increases. The Eurasian steppe A horizon has characteristically more SOC accumulation because it is typically cooler and drier than other grassland regions.
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