1. Soil and Fertilizer Institute, and Ministry of Agriculture Key Laboratory of Plant Nutrition and Nutrient cycling, Chinese Academy of Agricultural Sciences, 12 Zhongguancun Nandajie, Beijing, 100081, China
2. Department of Land Resource Science, University of Guelph, Guelph, Ontario, N1G2W1, Canada
3. Graduate School of Chinese Academy of Agricultural Sciences, 12 Zhongguancun Nandajie, Beijing, 100081, China
4. China Program, International Plant Nutrition Institute (IPNI), 12 Zhongguancun Nandajie, Beijing, 100081, China