Principal investigators: H.A. Torbert
Associated with: USDA-ARS National Soil Dynamics Laboratory
Nitrous oxide (N2O) emissions are increasing at an unprecedented rate owing to the increased use of nitrogen (N) fertilizers. Thus, new innovative management tools are needed to reduce emissions. One potential approach is the use of microbial inoculants in agricultural production. In a laboratory incubation study, reductions in N2O emissions were observed when microbial-based inoculants were added to soil (no plants present) with N fertilizers. Further study evaluated the effects of microbial-based inoculants on N2O emissions when applied to soil planted with corn (Zea mays L.) under controlled greenhouse conditions. Inoculant treatments consisted of (i) SoilBuilder (SB), (ii) a metabolite extract of SoilBuilder (SBF), and (iii) a mixture of 4 strains of plant-growth- promoting Bacillus spp. (BM). Experiments included an unfertilized control and 3 N fertilizers: urea, urea – ammonium nitrate with 32% N (UAN-32), and calcium – ammonium nitrate with 17%N(CAN-17). Cumulative N2O fluxes showed significant reductions in N2O of 15% (SB), 41% (BM), and 28% (SBF) with CAN-17 fertilizer. When UAN-32 was used, reductions of 34% (SB), 35% (SBF), and 49% (BM) were obtained. However, no reductions in N2O emissions occurred with urea. N uptake was increased by an average of 56% with microbial inoculants compared with the control (nonmicrobial-based treatments). Overall, results demonstrate that microbial inoculants can reduce N2O emissions following fertilizer application depending on the N fertilizer type used and can enhance N uptake and plant growth. Future studies are planned to evaluate the effectiveness of these microbial inoculants in field-based trials and determine the mechanisms involved in N2O reduction.
Calvo, P., D.B. Watts, J.W. Kloepper, and H.A. Torbert. 2016. Application of microbial-based inoculants for reducing N2O emissions from soil under two different ammonium nitrate-based fertilizers. Soil Sci. 181:427-434.
Calvo, P., D.B. Watts, J.W. Kloepper, and H.A. Torbert. 2016. The influence of microbial-based inoculants influence on N2O emissions from soil planted with Corn (Zea mays L.) under greenhouse conditions with different nitrogen fertilizer regimens. Can. J. Microbiol. 62:1041-1056.