Ammonium oxidation kinetics in the presence of nitrification inhibitors DCD and DMPP at various temperatures

Use of N-based fertilisers in combination with nitrification inhibitors lengthens N presence in the ammonium form in soil (N-NH4+), with beneficial effects for agriculture and related ecosystems. The efficiency of these inhibitors depends on several factors, the most important being soil temperature. This paper studies the effects of soil temperature on the kinetics of N-NH4+ loss in the presence of the DCD and DMPP nitrification inhibitors. For a 105-day period, 3 chambers, each with 12 containers holding 500 g of dry soil, were incubated at 10, 20, and 30degreesC. Ammonium sulfate was applied to 4 containers in each chamber; in another 4 containers Basammon Stabil, a N fertiliser with DCD, was used; and Entec 26, a fertiliser with DMPP, was used in the remaining 4 containers. Soil ammonium content was periodically determined for each container. Both DCD and DMPP lengthened ammonium presence in soil in a similar manner. However, their effectiveness was drastically decreased at increased soil temperatures. Thus, when using these inhibitors, soil temperature should be taken into account, especially in warm climate areas.