We will use a combination of field work, greenhouse experiments, incubations, laboratory methods (including physiochemical, molecular, and spectroscopic analyses), advanced imaging, stable isotope tracing, multi-omics (DNA/RNA sequencing, metabolomics, proteomics), and computational approaches to characterize and measure soil organic matter and its dynamic interactions with the ever-changing soil environment and its inhabitants. Our upcoming work will focus on mineral associated organic matter nitrogen (MAOM-N)—a critical but often overlooked component of soil organic matter. Recent works shows that MAOM may be both an important N sink and source. Since organic N is coupled to carbon (C) in soil, plant and microbial acquisition of MAOM-N likely influence soil organic C (SOC) turnover and persistence, as well. As part of a collaborative, multi-institutional project, we will investigate the following questions:
1. How do soil type, agricultural management practices, and environmental conditions influence MAOM-N pool size and availability?
2. How do roots and microbes mobilize MAOM-N; can MAOM-N supply crops with sufficient N?
3. Can MAOM-N pools be managed to provide crop N and simultaneously support SOC accrual?
We will use spectroscopy (e.g., FTIR, NEXAFS), sequential extractions, elemental and chemical analyses (e.g., IRMS, TOC, TON, FTICRMS), and imaging (e.g., SEM, TEM, IR microscopy, STXM-NEXAFS) to characterize MAOM-N present in paired soil samples maintained under annual wheat (conventional tillage and fertilization) vs perennial grasslands (no tillage or fertilization) across a gradient of soil texture and climatic conditions. Next, we will conduct incubations and greenhouse experiments to investigate how this MAOM-N is formed, transformed, and mobilized by plants and microbes. We will use stable isotope tracing to distinguish the fate of different organic matter inputs. Together, these efforts will help us understand how MAOM-N supports soil fertility and sustainable soil management.
