Arbuscular mycorrhizal fungi interactions in the nitrogen cycle for mitigating nitrous oxide emissions from agroecosystems – FUNCTION
Arbuscular mycorrhizal fungi interactions in the nitrogen cycle for mitigating nitrous oxide emissions from agroecosystems
Fertilizer use in agriculture has had enormous deleterious environmental consequences. Inefficient use of N fertilizer in agricultural soils results in the loss of N through nitrate leaching or emission of the greenhouse gas nitrous oxide, contributing to climate change, ozone depletion and major economic losses. Arbuscular mycorrhizal fungi are a key group of soil microbes that utilize and transfer N to symbiotic plant partners and have shown potential for reducing nitrous oxide emissions.
Determine the role of arbuscular mycorrhizal fungi in the N-cycle, their interactions with N-cycling microbes, and their involvement in mediating nitrous oxide emissions derived from N fertilizers.
N-cycling research has largely focused on prokaryotes and fungi that are directly involved in the processes of nitrification and denitrification, both of which produce nitrous oxide. However, the role of other organisms indirectly affecting these processes by mediating N availability is rarely considered. We currently have little knowledge about the role of arbuscular mycorrhizal fungi (AMF) in the N-cycle, and their impact on nitrous oxide emissions. Our current knowledge on microbes directly involved in the N-cycle has yet to be fully incorporated into a conceptual model, nor the mechanistic testing of the impact of AMF interactions on N-cycling processes. The objectives of this project are to determine the impact of AMF on nitrification and denitrification, N-cycling microbial groups, and derived nitrous oxide emissions under different fertilizer scenarios, and to validate and improve predicted models of soil nitrous oxide emissions.
A bespoke engineered plant-soil mesocosm system was designed for use in a series of experiments across an inorganic - organic N fertilization gradient. Incorporation of nitrification inhibitors and stable isotope techniques are being used for tracing the fate and fluxes of N compounds in the mesocosms. Soil nitrous oxide emissions are monitored using an autonomous gas analysis system that continuously records nitrous oxide using infrared spectrophotometers. Changes in microbial communities and genes involved in N-cycling are being monitored using qPCR, metagenomics and metatranscriptomics.
Experiments are ongoing and initial results suggest that arbuscular mycorrhizal fungi increase plant biomass and negatively impact the abundance of nitrifiers across the N inorganic - organic fertilization gradient.
As the project is only approaching the halfway point, there are no changes to the original objectives being pursued.
The drafting of manuscripts from this work are in progress.
Fertilizer use in agriculture has had enormous deleterious environmental consequences. The inefficient use of nitrogen (N) fertilizer in agricultural soils results in the loss of N through nitrate leaching or emission of the greenhouse gas nitrous oxide (N2O), contributing to climate change, ozone depletion and major economic losses. The rate at which anthropogenic-derived N is returned to the atmosphere, including the proportion as N2O, is largely governed by the ecology and biology of the microorganisms involved. Arbuscular mycorrhizal fungi (AMF) are a key group of soil microorganisms that utilize and transfer N to symbiotic plant partners, and have shown potential for reducing N2O emissions. However, these mechanisms have yet to be determined. FUNCTION will define the role of AMF in the N-cycle via their interaction with microorganism that contribute both direct and indirectly to N2O production in agroecosystems and their involvement in mediating N2O emissions derived from N fertilizer inputs in soil. We predict that AMF will have consequences on the growth and activity of N-cycling microbial groups, and will test our conceptual model which focuses on the contribution of ammonia oxidizers and denitrifiers to nitrification and denitrification, respectively, based on sources of ammonia (inorganic fast and slow release N fertilizer and organic N fertilizer) and potential competition with AMF for N, and the subsequent impact on N2O emissions. Ultimately, FUNCTION will determine the extent to which AMF mitigate N2O emissions under different N fertilizer scenarios and the mechanisms responsible. The resulting quantitative data will be used for improving existing N2O modelling approaches that currently do not consider differences in the resulting interactions between AMF and N-cycling microbial groups.
Project coordination
Christina Hazard (Laboratoire Ampère)
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
Partner
Ampère Laboratoire Ampère
Help of the ANR 298,490 euros
Beginning and duration of the scientific project:
February 2021
- 42 Months
