[1] State Key Lab Grassland Agroecosyst, Lanzhou 730000, Gansu, Peoples R China
[2] Minist Agr & Rural Affairs, Key Lab Grassland Livestock Ind Innovat, Lanzhou 730000, Gansu, Peoples R China
[3] Gansu Tech Innovat Ctr Western China Grassland In, Minist Educ, Engn Res Ctr Grassland Ind, Lanzhou 730000, Gansu, Peoples R China
[4] Lanzhou Univ, Coll Pastoral Agr Sci & Technol, Lanzhou 730000, Gansu, Peoples R China
[5] Gansu Prov Bur Geol & Mineral Resources, Inst Geol & Mineral Explorat 3, Lanzhou 730030, Gansu, Peoples R China
[6] Gansu Nonferrous Engn Explorat & Design Res Inst, Lanzhou 730030, Gansu, Peoples R China
[7] Univ Catholique Louvain UCLouvain, Earth & Life Inst, Soil Sci, B-1348 Louvain La Neuve, Belgium