ARS | Publication request: Manipulations of soil microbiota for C sequestration and mitigation of greenhouse gas emissions in managed systems

Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: June 30, 2011
Publication Date: N/A

Technical Abstract: Soil microbes dominate processes that regulate soil trace gas emissions and soil C and N dynamics. Intensive management in agroecosystems provides unique opportunities to assess the effectiveness of microbial manipulations to enhance soil C retention and reduce trace gas emissions. While reduced tillage can be conducive to the development of the soil microbial community with fungal dominance and facilitate soil C retention, direct inhibition of nitrifying bacteria has been shown to effectively reduce nitrous oxide emission and enhance soil N retention. However, it is unclear whether and how inhibition of nitrification affects soil C dynamics. Inhibition of nitrification would increase soil ammonium and alter plant C allocation to roots and mycorrhizal fungi, potentially affecting organic C inputs to soil and microbial activities. Using wheat as a model plant, we conducted both field and microcosm experiments examining the impact of a nitrification inhibitor (dicyandiamide, DCD) on soil microbes and organic residue decomposition under both ambient and elevated carbon dioxide. Our preliminary results from the microcosm experiment showed that elevated carbon dioxide, but not the nitrification inhibitor, significantly increased mycorrhizal colonization of roots. Inhibition of nitrification appeared to increase soil N retention, but did not affect plant N uptake. The impact of the nitrification inhibitor on residue decomposition and organic C dynamics in soil is being examined.