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Acta Prataculturae Sinica ›› 2018, Vol. 27 ›› Issue (12): 22-33.

### Effects of different management strategies on soil organic carbon and nitrogen pools in arid areas and their influencing factors

JIANG La-mei1, 2, YANG Xiao-dong1, 2, 3, YANG Jian-jun1, 2, 3, HE Xue-min2, 3, LÜ Guang-hui2, 3, *

1. 1.The College of Resource Environment Science of Xinjiang University, Urumqi 830046, China;
2.Ministry of Education Key Laboratory of Oasis Ecology of Xinjiang University, Urumqi 830046, China;
3.Research Institute of Arid Ecological Environment of Xinjiang University, Urumqi 830046, China
• Received:2018-01-25 Revised:2018-06-06 Online:2018-12-20 Published:2018-12-20
• Contact: E-mail:ler@xju.edu.cn

Abstract: The organic carbon content and total nitrogen content in soil and their dynamic balance are important indicators of the quality of soil and grassland. The aim of this study was to determine the effects of different management strategies on the quality of soil and grassland in the Xinjiang Aletai area. We analyzed soil in grasslands under three different management strategies (natural pasture, grazed pasture, and abandoned grassland), and determined soil organic carbon content, total nitrogen content, soil moisture, aggregate structure, pH, soil bulk density, and the relationships among these parameters. The soil carbon∶nitrogen ratio, total nitrogen content, organic carbon content, and total nitrogen reserves increased significantly with increasing soil depth (P<0.05). The soil total nitrogen contents and organic carbon contents in the 0-10 cm, 10-30 cm, and 30-50 cm soil layers were higher in natural grassland and grazed grassland than in abandoned grassland, but the soil carbon∶nitrogen ratio did not differ among the three types of grasslands. In the 0-10 cm, 10-30 cm, and 30-50 cm soil layers, soil conductivity and pH were significantly higher in grazed grassland than in natural grassland (P<0.05). In the 0-10 cm and 30-50 cm soil layers, the soil moisture content was significantly higher in grazed grassland than in abandoned grassland (P<0.05). The intermediate aggregate content differed significantly between abandoned grassland and the other two types of grasslands (P<0.05). Data for soil carbon content, nitrogen storage, and physical and chemical factors were used in correlation and canonical correlation analyses. In these analyses, the soil water content, aggregates, intermediate aggregates, micro aggregates, pH, and conductivity were explanatory variables, and soil nitrogen reserves and soil organic carbon reserves were the response variables. The explanatory factors explained up to 75.70% of the variation in soil nitrogen and soil organic carbon reserves, with soil moisture and aggregate structure showing strongest correlations with the response variables. We concluded that the soil carbon and nitrogen contents and reserves differed among the different management strategies, and that soil moisture content and soil aggregate structure were the main variables affecting soil carbon and nitrogen pools. Water content was strongly related to soil moisture and aggregate structure.