Nature Environment and Pollution Technology

Jianping Li ¹, Yingzhong Xie ¹, Lei Deng ², Kaibo Wang ², Xiaowei Li ¹

Affiliations
1 School of Agriculture, Ningxia University, Yinchuan, Ningxia, 750021, CN
2 State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A & F University, Yangling, Shaanxi 712100, CN

Abstract

Continually growing alfalfa (Medicago sativa) is very common in the dry land region of the Loess Plateau, China. The objective was to study the dynamics of the soil physico-chemical properties in alfalfa field soils over time. The space-for-time method was used to study a succession gradient of alfalfa, which were seven aged fields (1, 5, 8, 11, 15, 18 and 22 years). The results showed that the soil water content increased between 1 and 11 years, and then significantly decreased at 15 years (6.9%), finally, increased from 15 to 22 years. Soil bulk density continually decreased, and the variability between each layer for a given growing year significantly fell from 1 to 22 years. Long-term (up to 22 years) alfalfa cultivation has an important influence on the soil structure of the upper layer (0- 70 cm), but has little effect on the deeper soil layer (70-100 cm). The soil organic carbon and soil carbon storage for the different soil layers in different planting years first decreased (1-11 years) and then increased (11-22 years). Total nitrogen storage (0-100 cm) first increased (1-5 years) and then decreased (after 5 years). The soil available K storage and soil alkali-hydrolyzale N storage, both increased as the number of cultivation years rose.

Keywords

Alfalfa, Soil Organic Carbon, Soil N Storage, Soil Structure.

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