Application of Microbial Inoculants As Tools for Reducing Nitrous Oxide Emissions From Different Nitrogen Fertilizers.

Emissions of nitrous oxide (N₂O) are increasing due to several factors, including increased use of nitrogen fertilizers. New management tools are needed to reduce N₂O emissions from production agriculture. One potential such tool is the use of microbial inoculants, which are increasingly being used in agriculture. In a previous soil incubation study, we found that application of microbial-based treatments reduced N₂O emissions when nitrogen fertilizers were present. The current study compared emissions of N₂O and CO₂ following applications of microbial based treatments to corn planted in field soil in a greenhouse test. Treatments consisted of SoilBuilder (SB) from Agricen Science, a metabolite extract of SoilBuilder (SBF), and a mixture of PGPR bacilli (BM).  Experiments included three nitrogen fertilizers: urea, urea ammonium nitrate 32% N (UAN), and calcium ammonium nitrate 17% N (CAN) and an un-fertilized control. Cumulative fluxes of N₂O from pots at 41 DAP showed significant reductions of 15% (SB), 41% (BM) and 28% (SBF) with CAN fertilizer. When UAN was used, reductions of 34% (SB), 35% (SBF), and 49% (BM) were obtained. However, no reduction of N₂O occurred with urea fertilizer. Nutrient uptake (N, P, and K) and plant growth was also increased by microbial treatments. Overall, the results demonstrate that microbial inoculants can reduce emissions of N₂O resulting from nitrogen fertilizer application depending on the type of N fertilizer and they also enhanced the nutrient uptake and plant growth. Future studies are planned to determine the mechanisms of N₂O reduction by microbial inoculants.