Optimizing Biological Nitrification Inhibitors for the Suppression of N2O Emissions from Agricultural Soils

Faculty Lead: Darcy McRose, Assistant Professor, Department of Civil and Environmental Engineering at MIT

Although the use of nitrogen fertilizers is essential for agricultural productivity, much of the fertilizer applied to fields is lost before it reaches plants. One particularly problematic fate for nitrogen fertilizer is its conversion to the climate-active gas nitrous oxide (N₂O) by soil microbes. This microbial transformation is ubiquitous in crop soils and makes agriculture a major anthropogenic source of N₂O. Several synthetic small molecule inhibitors that target the microbes responsible for nitrification, the first step in the process, are in use today. More recently, plant-derived inhibitors have emerged as a complementary strategy to combat N₂O release from soils. While these biological nitrification inhibitors (BNI) are incredibly promising, we lack a mechanistic understanding of how they affect soil microbes and how their efficacy fluctuates under different environmental conditions. This proposal will address key knowledge gaps in our understanding of how biological nitrification inhibitors alter N₂O release from pure microbial cultures, simple microbial consortia, and crop soils. Our goal is to provide quantitative information needed to assess the feasibility of using these inhibitors and to identify optimal management practices. We are particularly interested in producing results that can be translated to management practices, such as changes in the timing of BNI additions or alterations in irrigation patterns (which largely control soil oxygen) that might make these interventions most effective.