1. Shanxi Academy of Agricultural Sciences, Institute of Agricultural Environment and Resources, Taiyuan, Shanxi, China
2. Key Laboratory of Soil Environment and Nutrient Resources of Shanxi Province, Taiyuan, Shanxi, China
3. College of Biological Engineering, Shanxi University, Taiyuan, Shanxi, China
4. Department of Crop and Soil Environmental Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA