Difficultly Extractable Fixed Ammonium in Some Soils of China

摘要

Ninety-three soil samples and 19 sedimentary rock samples collected from 21 provinces of China were analyzed for their contents of fixed ammonium and that is not determinable by Kjeldahl-HF method. Results showed that amount of difficultly extractable fixed ammonium (the fixed ammonium that is not determinably by Kjeldahl procedures commonly used for soils) in soils ranged from 0 to 202 mg kg~-1. It was generally more than 50 mg kg~-1 in soils in Changji and Turpan districts, Xinjiang, accounting for 3.2/100￣36.8/100 with an average of 13.9/100 of the total N.