Modification of the standard method for determination of non-exchangeable NH4-N in soil

Abstract

It is well accepted that non-exchangeable NH₄-N plays an important role in the N dynamics of arable soils. However the widely-used Silva/Bremner method for determining this N fraction is very time consuming and the use of the hazardous hydrofluoric acid (HF) is indispensable. In the modification the use of HF is avoided and the quantity of analysed samples per unit of time could be increased by a factor of 2.5. After pretreating soil samples with KOBr to destroy soil organic matter soil samples are dried and the content of non-exchangeable NH₄-N is measured using a CNS analyzer. The results of the analysis of 3 out of 4 different soils show no significant differences between both methods.