Related Experiment Video
Updated: Jul 14, 2026
11:53
Spatial Multiobjective Optimization of Agricultural Conservation Practices using a SWAT Model and an Evolutionary Algorithm
Published on: December 9, 2012
Modeling riverine nitrate export from an East-Central Illinois watershed using SWAT
1Department of Civil and Environmental Engineering, Urbana, IL, USA. xuetaohu@uiuc.edu
Journal of Environmental Quality
|May 29, 2007
Summary
This study assessed the Soil and Water Assessment Tool (SWAT) for predicting agricultural nutrient management impacts. While streamflow was well-simulated, nitrate export predictions require improvement for reliable water quality forecasting in tile-drained watersheds.
Area of Science:
- Environmental modeling
- Agricultural science
- Water resource management
Background:
- Agricultural nutrient management significantly impacts water quality.
- Accurate modeling is crucial for predicting the effects of nutrient management strategies.
- Tile-drained watersheds with intensive agriculture present unique modeling challenges.
Purpose of the Study:
- To apply and evaluate the Soil and Water Assessment Tool (SWAT) for simulating water quality and crop yield in a tile-drained agricultural watershed.
- To assess the model's ability to predict the impact of reduced nitrogen fertilizer application on nitrate export and crop production.
- To identify limitations of the SWAT model in simulating nutrient cycling and water quality in intensively managed agricultural systems.
Main Methods:
- Application of the Soil and Water Assessment Tool (SWAT) version 2000.
- Calibration and validation of the model using streamflow, nitrate loads, crop yield, and nitrogen budgets from 1985 to 2002.
- Simulation of nutrient management scenarios involving 10-50% reduction in nitrogen fertilizer rates.
Main Results:
- SWAT accurately simulated streamflow (E: 0.67–0.94, R(2): 0.75–0.95) but showed weaker performance for nitrate (NO(3)) loads (E: -0.16–0.45, R(2): 0.36–0.74).
- Simulated crop yields had low relative errors (-10 to 6%).
- Reduced nitrogen fertilizer rates (10-50%) predicted a 10-43% decrease in NO(3) export and a 6-38% reduction in maize yield, though overestimations during wet periods and unrealistic N-cycle changes were noted.
Conclusions:
- The SWAT model provides a basis for assessing nutrient management impacts but requires improvements for accurate nitrate export prediction in tile-drained systems.
- Overestimation of nitrate export during wet periods and unrealistic nitrogen fixation rates highlight areas for model enhancement.
- Further model development is needed to reliably predict water quality outcomes of nutrient management in complex agricultural watersheds.
