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Microbial-Based Inoculants Impact Nitrous Oxide Emissions from an Incubated Soil Medium Containing Urea Fertilizers

Author:
Pamela Calvo, Dexter B. Watts, Robert N. Ames, Joseph W. Kloepper, H. Allen Torbert
Source:
Journal of environmental quality 2013 v.42 no.3 pp. 704-712
ISSN:
0047-2425
Subject:
aerobic conditions, aerobiosis, agricultural soils, anaerobic conditions, carbon dioxide, crop management, fertilizer application, gas chromatography, greenhouse gas emissions, microbial activity, nitrous oxide, nutrient uptake, plant growth-promoting rhizobacteria, root growth, soil quality, urea, urea fertilizers
Abstract:
There is currently much interest in developing crop management practices that will decrease N₂O emissions from agricultural soils. Many different approaches are being investigated, but to date, no studies have been published on how microbial inoculants affect N₂O emissions. This study was conducted to test the hypothesis that microbial-based inoculants known to promote root growth and nutrient uptake can reduce N₂O emissions in the presence of N fertilizers under controlled conditions. Carbon dioxide and CH₄ fluxes were also measured to evaluate microbial respiration and determine the aerobic and anaerobic conditions of the incubated soil. The microbial-based treatments investigated were SoilBuilder (SB), a metabolite extract of SoilBuilder (SBF), and a mixture of four strains of plant growth-promoting Bacillus spp. Experiments included two different N fertilizer treatments, urea and urea–NH₄NO₃ 32% N (UAN), and an unfertilized control. Emissions of N₂O and CO₂ were determined from soil incubations and analyzed with gas chromatography. After 29 d of incubation, cumulative N₂O emissions were reduced 80% by SB and 44% by SBF in soils fertilized with UAN. Treatment with Bacillus spp. significantly reduced N₂O production on Days 1 and 2 of the incubation in soils fertilized with UAN. In the unfertilized treatment, cumulative emissions of N₂O were significantly reduced 92% by SBF. Microbial-based treatments did not reduce N₂O emissions associated with urea application. Microbial-based treatments increased CO₂ emissions from soils fertilized with UAN, suggesting a possible increase in microbial activity. Overall, the results demonstrated that microbial-based inoculants can reduce N₂O emissions associated with N fertilizer application, and this response varies with the type of microbial-based inoculant and fertilizer.
Agid:
56921
Handle:
10113/56921