1. Center for Resources, Environment and Food Security (CREFS)College of Resources and Environmental SciencesChina Agricultural Univ.Beijing100193China
2. Key Lab. of Arable Land Conservation (Middle and Lower Reaches of Yangtze River)Ministry of AgricultureCollege of Resources and EnvironmentHuazhong Agricultural Univ.Wuhan430070China
3. CSIRO Agriculture and FoodGPO Box 1700CanberraACT2601Australia
4. Inner Mongolia Key Lab. of Soil Quality and Nutrient ResourcesKey Lab. of Grassland Resource (IMAU)Ministry of EducationCollege of GrasslandResources and EnvironmentInner Mongolia Agricultural Univ.Hohhot 010018China