Long-term DSSAT simulation of nitrogen loss to artificial subsurface drainage flow for a corn-soybean rotation with winter rye in Iowa

Authors: Chatterjee, Amitava; Thorp, Kelly; O'Brien, Peter; Kovar, John; Rogovska, Natalia; Malone, Robert

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/27/2025
Publication Date: 4/1/2025
Citation: Chatterjee, A., Thorp, K.R., O'Brien, P.L., Kovar, J.L., Rogovska, N.P., Malone, R.W. 2025. Long-term DSSAT simulation of nitrogen loss to artificial subsurface drainage flow for a corn-soybean rotation with winter rye in Iowa. Agricultural Water Management. https://doi.org/10.1016/j.agwat.2025.109464.
DOI: https://doi.org/10.1016/j.agwat.2025.109464

Interpretive Summary: Nitrate is an especially mobile form of soil nitrogen that can contaminate groundwater, streams and lakes. In the Great Plains area, growing cereal rye after harvest of the main crop can reduce the loss of nitrate nitrogen through artificial drainage by subsurface tile drainage pipes. Crop simulation models use local weather data, crop and soil management information to predict crop yields and tile flow (the water that is drained from soil through the tiles) and nitrate concentration in tile flow. This study was conducted in central Iowa to determine the performance of the Decision Support for Agrotechnology Transfer (DSSAT) model in comparison to field measurements of crop yield and nitrate loss with and without cereal rye grown during the off-season as a cover crop. Results from both the model and field measurements showed that growing a cereal rye cover crop can reduce nitrate loss by 57%. In addition, early or late killing of cereal rye in the spring by 10 days before or 10 days after the normal kill time did not increase tile nitrate loss. However, the model performed poorly in predicting cereal rye biomass. These findings will be useful to predict nitrate loss from fields having tile drainage systems installed. Findings will be of interest to scientists and land managers who are planning to manage tile nitrate loss using cereal rye in central Iowa.

Technical Abstract: Growing winter cover crops like cereal rye (Secale cereale L.) can reduce nitrate (NO3-) loss through subsurface tile drainage in the Midwest Corn Belt of the United States. The widely used Decision Support System for Agrotechnology Transfer (DSSAT) model can simulate processes of artificial subsurface drainage flow and NO3- loss to artificial subsurface drainage, but few model evaluations with field-measured data are available. The objective was to evaluate the DSSAT model for simulating flow and NO¬3 losses to tile drainage in a corn (Zea mays L.) -soybean (Glycine max L.) rotation with (CC) and without (NCC) winter rye cover crop in Central Iowa during the 2002-2010 growing seasons. Simulations successfully reproduced the cumulative (9-yr.) subsurface drainage flow (NSE =0.82) and NO3- loss in flow (NSE= 0.5). Both simulated and measured data for cumulative (9 yr.) NO3- in tile drainage demonstrated that the CC treatment could reduce NO3- in drainage by 57%. The percent errors between measured and simulated corn yield (n=5), soybean yield (n=4) and rye biomass (n=9) were 1.46%, 9.24% and 17.7%, respectively. The model did not perform well in simulating rye biomass after soybean (r2= 0.04) compared to after corn (r2=0.97). Changing cover crop termination by ±10 days did not influence the main crop yield and tile NO3 loss. The results suggest that DSSAT can appropriately simulate the influence of CC on N loss through tile drainage for a corn-soybean production system in Iowa.