TESTING THE INFLUENCE OF CHEMICALS ON SOIL AUTOTROPHIC AMMONIUM OXIDATION

Nitrification is crucial for the content of inorganic nitrogen in soil and hence of considerable ecological and agricultural importance. The first step in the nitrification process, the oxidation of ammonium to nitrite, is particularly sensitive to chemicals, and the ammonium oxidation activity of soils may thus be used as an indicator of chemical disturbances. A method for the determination of potential nitrification has been tested that measures ammonium oxidation specifically and under optimal conditions, has a good reproducibility, and makes it possible to screen a large number of chemicals during a short period of time. The method has been tested with a number of pesticides. Dithiocarbamate fungicides gave the most pronounced inhibition of ammonium oxidation.