1. Ministry of Agriculture Key Lab. of Crop Nutrition and Fertilization Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences Beijing 100081 P.R. China
2. International Plant Nutrition Institute China Program Beijing 100081 P.R. China
3. Institute of Plant Nutrition and Resources, Beijing Academy of Agriculture and Forestry Sciences, Beijing Engineering Technology Research Center for Slow/Controlled‐Release Fertilizer Beijing 100097 P.R. China
4. College of Resources and Environment Henan Agricultural University Zhengzhou 450002 P.R. China
5. Institute of Agricultural Resources and Environment, Hebei Academy of Agriculture and Forestry Sciences Shijiazhuang 050051 P.R. China
6. Institute of Agricultural Resources and Environment, Shandong Academy of Agricultural Sciences Jinan 250100 P.R. China
7. Institute of Agricultural Resources and Environment, Shanxi Academy of Agricultural Sciences Taiyuan 030031 P.R. China