| Abstract: | The widely-used Silva-Bremner method for determining non- exchangeable NH4?N in the soil was modified so as to reduce reagent requirement and the time taken to carry out the analyses. In the modification, boiling the mixture of soil and KOBr on a hot plate was replaced with heating the soil/KOBr mixture, directly placed in centrifuge tubes, in a boiling water bath or a microwave oven. The best procedure is to keep the soil/KOBr mixture for 10 minutes in the water bath or for 10 minutes at 50% of full power in a microwave oven. The modified method gave similar values to the standard method on 4 quite different soils and also slightly increased reproducibility. |
