Stimulating effect of earthworm excreta on the mineralization of nitrogen compounds in soil

The effect of excreta of earthworm species Aporrectodea caliginosa and Eisenia fetida on the mineralization of nitrogen compounds in soils has been studied. A single application of excreta obtained from three earthworms in one day increased the formation of nitrate nitrogen compounds in the soil by 10–50%. The application of ammonium nitrogen (in the form of NH₄Cl) in amounts equivalent to the ammonium nitrogen content in the daily excreta of three earthworms had the same effect on the mineralization of nitrogen compounds. The effect of earthworm excreta, as well as the effect of ammonium nitrogen, on the nitrification process was an order of magnitude higher than their contribution to the formation of nitrates due to the oxidation of the introduced ammonium. Hence, ammonium—an important component of the earthworm excreta—can exert a stimulating effect on nitrification processes in the soil and produce long-term cumulative effects that are much more significant than the direct effect of this nitrogen compound.