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Microbial‐Based Inoculants Impact Nitrous Oxide Emissions from an Incubated Soil Medium Containing Urea Fertilizers
Author(s) -
Calvo Pamela,
Watts Dexter B.,
Ames Robert N.,
Kloepper Joseph W.,
Torbert H. Allen
Publication year - 2013
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2012.0300
Subject(s) - microbial inoculant , nitrous oxide , soil water , chemistry , fertilizer , agronomy , incubation , nutrient , urea , carbon dioxide , environmental chemistry , environmental science , bacteria , biology , biochemistry , organic chemistry , soil science , genetics
There is currently much interest in developing crop management practices that will decrease N 2 O emissions from agricultural soils. Many different approaches are being investigated, but to date, no studies have been published on how microbial inoculants affect N 2 O emissions. This study was conducted to test the hypothesis that microbial‐based inoculants known to promote root growth and nutrient uptake can reduce N 2 O emissions in the presence of N fertilizers under controlled conditions. Carbon dioxide and CH 4 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–NH 4 NO 3 32% N (UAN), and an unfertilized control. Emissions of N 2 O and CO 2 were determined from soil incubations and analyzed with gas chromatography. After 29 d of incubation, cumulative N 2 O emissions were reduced 80% by SB and 44% by SBF in soils fertilized with UAN. Treatment with Bacillus spp. significantly reduced N 2 O production on Days 1 and 2 of the incubation in soils fertilized with UAN. In the unfertilized treatment, cumulative emissions of N 2 O were significantly reduced 92% by SBF. Microbial‐based treatments did not reduce N 2 O emissions associated with urea application. Microbial‐based treatments increased CO 2 emissions from soils fertilized with UAN, suggesting a possible increase in microbial activity. Overall, the results demonstrated that microbial‐based inoculants can reduce N 2 O emissions associated with N fertilizer application, and this response varies with the type of microbial‐based inoculant and fertilizer.