JOURNAL OF NATURAL RESOURCES ›› 2011, Vol. 26 ›› Issue (11): 1890-1899.

• Resources Ecology •

### Distribution Characteristics of Soil Organic Carbon Fractions of the Typical Soil Types on the Loess Plateau

DANG Ya-ai1,3, WANG Guo-dong3, LI Shi-qing1,2, SHAO Ming-an1,2

1. 1. State Key Labarotary of Soil Erosion and Dryland Farming on Loess Plateau,Northwest A & F University, Yangling 712100,China;
2. Institute of Soil and Water Conservation,CAS,Yangling 712100,China;
3. College of Science,Northwest A & F University,Yangling 712100,China
• Received:2011-01-10 Revised:2011-05-24 Online:2011-11-20 Published:2011-11-20

Abstract: In order to evaluate the effects of location, soil depth, and land use on the soil light fraction organic carbon (LFOC) and soil heavy fraction organic carbon (HFOC), we investigated the contents and the distribution characteristics of soil LFOC and HFOC of three types (Ust-Sandiic-Entisols at Shenmu, Los-Orthic-Entisol at Yan’an and Eum-Orthic-Anthrosol at Yangling) soils profiles (0－200 cm) sampled along a north-south gradient on the Loess Plateau. The results indicated that the contents of soil LFOC and HFOC decreased significantly (P<0.05) from south to north. The ratios of LFOC in soil organic carbon ranged from 1% to 26%. LFOC content and the ratios of LFOC in soil organic carbon significantly (P<0.05) decreased with soil depth. Both of them were lower than the previous reports in other regions of China. Land use closely (P<0.05) correlated with the contents of LFOC and HFOC fractions in the upper soil layers.Compared with farmland, the contents of soil LFOC and HFOC in grassland were significantly higher at the 0－60 cm layers, but had no significant difference below 60 cm soil layers. Both soil LFOC and HFOC contents positively correlated with soil microbial biomass nitrogen and carbon contents, the former with a correlation coefficient of 0.841 and 0.507, respectively. This suggested that soil LFOC was one of the most important carbon and energy sources for soil microbial growth and thus more liable to the impacts of microbial activities and land use change. Our results also implied that soil LFOC could more effectively reflect the variation of soil organic carbon pools than HFOC.

CLC Number:

• S153.6