Simulating nitrate and pesticide concentrations in the subsurface drain water using the DRAINAGE model

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1996
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Kumar, Ajay
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Rameshwar S. Kanwar
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Agricultural and Biosystems Engineering

Since 1905, the Department of Agricultural Engineering, now the Department of Agricultural and Biosystems Engineering (ABE), has been a leader in providing engineering solutions to agricultural problems in the United States and the world. The department’s original mission was to mechanize agriculture. That mission has evolved to encompass a global view of the entire food production system–the wise management of natural resources in the production, processing, storage, handling, and use of food fiber and other biological products.

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In 1905 Agricultural Engineering was recognized as a subdivision of the Department of Agronomy, and in 1907 it was recognized as a unique department. It was renamed the Department of Agricultural and Biosystems Engineering in 1990. The department merged with the Department of Industrial Education and Technology in 2004.

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1905–present

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  • Department of Agricultural Engineering (1907–1990)

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This study was conducted to simulate the nitrate and pesticide concentrations in subsurface drain water. Nitrate and pesticide components, based on the GLEAMS model, were developed and incorporated into the DRAINAGE model. The hydrology component of the DRAINAGE model was also modified by changing the soil layer thickness and by incorporating a preferential flow subroutine. The DRAINAGE model was modified by reducing soil layer thickness to 5 cm and was extended to simulate the effects of different tillage systems on subsurface drainage water quality and quantity. The DRAINAGE model was also modified by adding a new nitrogen subroutine based on the GLEAMS model. The modified model was used to simulate subsurface drain flows and NO3-N concentrations in the drain water for the years 1984 through 1993 for a site located at the Agricultural Engineering and Agronomy Research Center (AEARC) near Ames, Iowa;The predicted subsurface drain flows by the model were compared with the observed subsurface drain flows. The comparison between simulated and observed drain flows indicates that the modified DRAINAGE model is capable of simulating subsurface drain flows and NO3-N concentrations in the subsurface drainage water. The model predicted results followed the trend of observed data reasonably well. However, the modified DRAINAGE model tends to underpredict peak subsurface drain flows. Overall predictions of subsurface drain flows by the modified DRAINAGE model showed that reduced soil layer thickness significantly improved the model performance;Simulated NO3-N concentrations were compared with the observed NO3-N concentrations for the years 1984 through 1993. The comparison between simulated and observed NO3-N concentrations showed that model predictions were in close agreement with the observed NO3-N concentrations in subsurface drain flows. The NO3-N concentrations in the soil profile were also simulated and showed that model predictions were within a ± one standard deviation range from observed data;The preferential flow component was added to the DRAINAGE model and was validated with the observed data obtained from Iowa State University's Nashua Water Quality Site at Nashua, Iowa for 1990 to 1992. Predicted subsurface drain flows were improved with the addition of the preferential flow component. The preferential flow component also improves the predictions of drain flow peaks. The model was further modified by adding a pesticide component to predict pesticide concentrations in subsurface drain water. The predicted atrazine concentrations in subsurface drain flows compared reasonably well with observed data. Finally, a study was conducted to compare the performance of the DRAINAGE and the RZWQM models in predicting subsurface drain flows, and NO3-N and atrazine concentrations in the subsurface drain water. Results of this study indicate that the modified DRAINAGE model performs slightly better than the RZWQM. The modified DRAINAGE model showed that model is capable of predicting subsurface drain flows (including preferential flow) and NO3-N and atrazine concentrations in the subsurface drain water reasonably well.

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Mon Jan 01 00:00:00 UTC 1996