|CALVO, PAMELA - Auburn University|
|KLOEPPER, JOSEPH - Auburn University|
|Torbert, Henry - Allen|
Submitted to: Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/5/2016
Publication Date: 9/1/2016
Publication URL: http://handle.nal.usda.gov/10113/5661734
Citation: Calvo, P., Watts, D.B., Kloepper, J.W., Torbert III, H.A. 2016. Application of microbial-based inoculants for reducing N2O emissions from soil under two different ammonium nitrate-based fertilizers. Soil Science. 181:427-434.
Interpretive Summary: Preventing nitrous oxide (N2O) emissions from agricultural fields continues to be an environmental issue world-wide. It has been proposed that the addition of beneficial microbes to soil could reduce N2O emissions. A study was performed to examine the effects of adding microbes known to improve plant growth on reducing N2O emissions. The microbial based treatments were SoilBuilder (SB), a metabolite extract of SoilBuilder (SBF), and a mixture of four Bacillus spp (BM). Experiments included two differ N fertilizers: ammonium nitrate 32%N (AN) and calcium ammonium nitrate 17% N (CAN). After 29 days of incubation, the microbial treatments effect on N2O emissions were different depending on the fertilizer used. Nitrous oxide emissions from soil fertilized with AN were lower than soil with CAN. However, the greatest reduction in N2O emissions was observed in the CAN soil. Cumulative N2O emissions were reduced 81%, 67%, and 50% for the SBF, SB, and BM treatments, respectively when the CAN was applied. In an unfertilized soil, SBF reduced cumulative N2O emissions 92%. Overall, this study proved that the use of microbial treatment can potentially reduce N2O emission.
Technical Abstract: Considerable effort is being made among the scientific community to identify mechanisms to reduce nitrous oxide (N2O) emissions from agriculture soils. Thus, the objective of this study was to test the hypothesis that microbial-based inoculants known to promote root growth and nutrient uptake will reduce N2O emissions in the presence of ammonium nitrate-based nitrogen fertilizers under controlled conditions. The microbial-based treatments evaluated were SoilBuilder (SB), a metabolite extract of SoilBuilder (SBF), and a mixture of four strains of plant growth-promoting Bacillus spp. Experiments included an unfertilized control and two different nitrogen fertilizers: ammonium nitrate (AN-32) and calcium ammonium nitrate (CAN-17). Measurements of N2O and carbon dioxide (CO2) were determined from soil incubations and analyzed with gas chromatography. After 29 days of incubation, cumulative N2O emissions were reduced 81%, 67%, and 50% for the SBF, SB, and BM treatments, respectively, in soils fertilized with CAN-17. In the unfertilized treatment, cumulative N2O emissions with SBF were significantly reduced 92%, and emissions at 2, 4, and 8 days of incubation were significantly reduced by SB and Bacillus. Emissions from the AN-32 treatment were generally lower than those from CAN-17. Microbial-based treatments increased N2O emissions when associated with AN-32 application, with SBF having the greatest flux. No differences in total CO2 emissions were observed among treatments when AN-32 was applied. Microbial-based treatments increased CO2 emissions from soils fertilized with CAN-17 and from the unfertilized control, indicating a possible increase in microbial activity. Overall, the results demonstrated that microbial-based inoculants can impact (reduce or increase) N2O emissions from soil. This response is highly dependent on the fertilizer type and microbial-based product applied.