Modeling the Impacts of Historical Weather and Management on Nitrogen Loss
There continues to be a need for more detailed information on where in the landscape and by how much recommended practices to reduce N loss can be expected to realistically mitigate water quality challenges, as well as their impacts on crop production.
This project will provide actionable data to inform stakeholders on
1) the contribution of controllable (management) and uncontrollable factors on water quality from 1980 to 2020, and
2) the effectiveness of three N loss reduction practices at scale: N fertilization amount, N fertilization timing and inclusion of cover crops.
Researchers will use the Agricultural Production Systems sIMulator (APSIM), a well-calibrated cropping systems model for Iowa, to perform a regional scale systems analysis (4,000 fields). The model will be driven by weather, soil and management databases that include tile drainage in the landscape, synthetic and organic N fertilizer by county and by year, annual changes in planting densities, cultivars and planting dates. By keeping one factor at a time constant we will determine the contribution of each factor on N loss, while a model sensitivity analysis will provide additional insights.