Smart residue amendments to improve greenhouse gas uptake by agricultural soils

• Applicant: Dr. Kristof Brenzinger
• Subject Area: Soil Sciences ; Microbial Ecology and Applied Microbiology ; Ecology of Land Use
• Term: from 2017 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 351977174

Multiple factors influence and contribute to global warming trends and climate change, however increasing greenhouse gases (GHG) emission mediated by anthropogenic activities is generally recognize as the major driver. Intensification of agricultural land use and excessive use of fertilizer to meet the global food, feed and bioenergy demand for the growing human population, can lead to the loss of soil methane uptake capacity and additionally leads to enhanced emission of nitrous oxide by lowering the rate of reduction of N2O to N2, which lead to an increase of CH4 and N2O emission in almost all studies. Therefore, future research must focus on understanding the underlying mechanisms of this effect to be able to develop strategies to reduce CH4 and N2O emission from agricultural soils, especially under ongoing fertilization regimes. Addressing these pressing issues, the objective of this proposal is to understand the influence of organic fertilizers on the microbe-plant-GHG balance relationship in agricultural soils. The study will focus on three major topics: 1. I aim to investigate the influence of a combination of organic amendments in agricultural soils on GHG balance, methane cycling and on N-transformation rates. 2. Furthermore, I will study the effect of the application of a variety of organic amendments on plants and their interaction with their associated microbial community in the rhizosphere. 3. Finally, I will identify the microbial communities involved in C- and N-cycle. During the two-year funding phase, I plan to set up a greenhouse experiment to investigate the influence of a combination of organic amendments (compost, biochar, mixture of cover crops residues) in agricultural soils on two important European crops (wheat and maize), the microbial community in the rhizosphere and the influence of the organic amendments on the GHG balance. GHG fluxes (CO2, CH4 and N2O) and the plant growth will be measured periodically under ambient air. After the gas measurement, samples of the soil will be taken from selected time points. From these soil samples methane oxidation rates, pH and soil nutrient contents (NOx, NH4+, and PO43-) are determined. For the molecular analyses, DNA from each sample will be quantitated by quantitative PCR of several important functional marker genes of the C- and N-cycle, which are included in GHG production and reduction (pmoA, amoA, nosZ). For further analyses of the microbial community composition a MiSeq Illumina sequencing will be set-up. I suggest that with an addition of smart mixes of organic amendments GHG emission from agricultural fields can be further reduced by alter several microbial metabolic and catabolic processes. With these approaches, I will shed light on the underlying mechanisms of how specialized organic fertilizers influence and possibly decrease GHG emission from agricultural soils without decreasing their biomass yield.

• DFG Programme: Research Fellowships
• International Connection: Netherlands
• Host: Privatdozent Dr. Paul Bodelier