PARENT SESSION
Poster Session #12: Modeling.
Tuesday, August 7, 2001. Presentation from 10:30 AM to 12:00 PM. Exhibition Hall
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Applying global ecosystem modeling tools to agriculture: continental-scale food production to precision farming.
Kucharik, Chris1, Brye, Kristofor2, Molling, Christine1, Donner, Simon1, 1 2
ABSTRACT- The increased dependence on chemical usage in agriculture over the past several decades has helped support increased crop yield, but could also be partially responsible for amplified year-to-year variability. Fertilizers have also contributed to significant loading of nitrate into our natural waterways. To address questions related to the simultaneous interaction of land management, nitrate leaching, and crop production across several scales, we adapted and modified Version 2 of the Integrated BIosphere Simulator (IBIS) to include managed agroecosystems. Our goal was to construct a process-based crop model that is applicable across large continental scales (~50 km resolution), but robust enough to be implemented at the precision agriculture scale (~ 5 m). This modeling approach integrates management decisions, including fertilizer input and planting date, with natural processes (soil physics, plant phenology, and N and C cycling), coupled to solute transport. Across the Upper Mississippi basin, we studied how past extreme weather events and soil spatial variability has influenced maize and soybean yield, characterized how different land-cover types influence hydrology, and estimated the amount of nitrate fertilizer transported to the river system by coupling IBIS runoff and drainage to a hydrologic routing model. Several comparisons between regional model output and available datasets demonstrate the utility of the model at large scales. At the individual field scale, IBIS simulations of drainage, nitrate leaching, yield, harvest index, and leaf area index during 1995-2000 were within 20% of measured quantities in maize agroecosystems at an agricultural research site in Wisconsin. For precision farming applications, the modified IBIS model was used to create a Precision Agricultural-Landscape Model (PALM), an important tool that can be used in real-time to show how growers might maximize yield while minimizing nitrate leaching.
KEY WORDS: agriculture, modeling, nitrate, leaching