The ¹³C and ¹⁵N Natural Abundances to Characterize Soil Organic Matter Associated with Clay Minerals in Eurasian Steppe Soils (THE 2nd INTERNATIONAL CONFERENCE ON ARID LAND (ICAL 2)) The <sup>13</sup>C and <sup>15</sup>N Natural Abundances to Characterize Soil Organic Matter Associated with Clay Minerals in Eurasian Steppe Soils
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Soil organic matter (SOM) associated with clay minerals plays an important role in maintaining fertility and storing carbon in soil. Moreover, for soil conservation, it is necessary to understand the nature of SOM associated with clay minerals in various environments. Our objective was to characterize SOM associated with clay minerals in Eurasian steppe soils using particle size fractionation and stable isotopic techniques. In this study, we collected 43 samples from grassland soils in Ukraine, Kazakhstan, and Mongolia as well as Xinjiang and Inner Mongolia in China, and conducted particle size fractionation to evaluate SOM associated clay minerals. The results revealed that SOM associated with clay minerals plays a key role in the fertility of Eurasian steppe soils (52.5% ± 9.0% C and 55.0% ± 8.2% N in total organic carbon and total nitrogen). The C/N ratio decreased in the following order: sand (13.5 ± 5.5) > silt (11.5 ± 2.0) > clay (8.6 ± 1.0). The δ<sup>13</sup>C and δ<sup>15</sup>N values of clay fractions were higher than those of silt and sand fractions in most samples. The C/N, δ<sup>13</sup>C, and δ<sup>15</sup>N values suggested that SOM associated with clay minerals contains more decomposed SOM. In addition, the difference of δ<sup>15</sup>N values between clay and silt fractions had a larger range than that of δ<sup>13</sup>C values. This indicated that δ<sup>15</sup>N values of SOM were a useful tool for clearly showing the difference of quality between particle size fractions in Eurasian steppe soils.
- Journal of Arid Land Studies
Journal of Arid Land Studies 25(3), 153-156, 2015
The Japanese Association for Arid Land Studies