Modeling the effects of management practices on soil greenhouse gas emissions and nutrient content for a corn-soybean system

Research Poster
Garrett Steinbeck
Sami Khanal
Department of Food, Agricultural and Biological Engineering

Garrett Steinbeck, Sami Khanal, Margaret Kalcic, and Kevin King
Food, Agricultural and Biological Engineering, The Ohio State University, Columbus, OH
USDA-ARS Soil Drainage Research Unit, Columbus, Ohio 43210, USAMonitoring of soil carbon and greenhouse gas (GHG) fluxes is challenging. Current field-based approaches are costly, and time intensive, and thus high-quality data are limited. The DeNitrification and DeComposition (DNDC) model is a biogeochemical model that has been widely used to simulate agriculture emissions, but calibration has predominately been carried out manually, which is time consuming and prone to high uncertainty in outputs. The goals of this study are to 1) develop and implement a framework for automated calibration and validation of DNDC and 2) examine the carbon sequestration and GHG reduction potential of a series of conservation practices in a corn-soybean rotation using DNDC model. The model was calibrated and validated using measured water and nitrate leaching and crop yield data over the years 2016-2017 from a field in corn-winter wheat-cover crop rotation under conventional tillage (CT), located in the Maumee River watershed in northwest Ohio. The model was integrated with PEST, an open-source parameter estimation and uncertainty analysis software, allowing for implementation of automated calibration using inverse modeling. Conservation practice scenarios simulated included no-till (NT) and winter wheat cover crop and the impact on daily and annual nitrous oxide (N2O) emissions and soil organic carbon (SOC). The DNDC model correctly predicted timing of N2O fluxes following major precipitation events and nitrogen fertilizer applications. Our preliminary assessment indicated greater annual "N" _"2"  "O"  emission under NT practices and significant decrease in SOC reduction when a cover crop is added to the crop rotation.