Effect of NPK fertilization and organic matter on the respiration dynamics and microbial N transformation processes of the soil.

Gulyas, F.; Szili-Kovacs, T.; Szegi, J.; Fuleky, G.; Tolner, L.

Abstract

Respiration and changes in the quantitative and qualitative composition of soil microflora reflected the changes in inorganic N-forms of the soil. In the case of cellulose application, the original NO₃-N and NH₄-N content, as well as the N content of NH₄-N fertilizer added to the soil, were immobilized during the first 10-12 day period of incubation. After this period the intensity of cellulose decomposition was controlled by the rate of organic-N mineralization. The number of the nitrifiers was lower in soil samples treated with cellulose in all cases. This shows the assimilation of soil ammonium-N in microbial biomass. Potential denitrification was faster than aerobic soil respiration, which may be due to the higher electron donor demand for denitrification.