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United States Department of Agriculture

Agricultural Research Service

Title: A Field Test of the Root Zone Quality Model (Rzwqm) for Multiple-Crop Fertilizer Fate and Transport in a Coastal Plain Field

Authors
item Schwartz, Liliana - U. OF GA
item Hubbard, Robert
item Wauchope, Robert
item Sheridan, Joseph
item Truman, Clinton
item Bosch, David

Submitted to: Soil and Water Conservation Society Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: February 20, 2003
Publication Date: February 20, 2003
Citation: Schwartz, L., Hubbard, R.K., Wauchope, R.D., Sheridan, J.M., Truman, C.C., Bosch, D.D. 2003. A field test of the root zone quality model (RZWQM) for multiple-crop fertilizer fate and transport in a coastal plain field [abstract]. Soil and Water Conservation Society Proceedings. Abstract no. 39.

Interpretive Summary: This abstract summarizes a study in which field measurements on the fate and transport of fertilizer chemical ' mainly nitrate'were analyzed using a computer simulation model. The model, RZWQM was built by ARS scientists to examine the effects of agricultural practices on water quality, and the field study was done on a small watershed at Tifton that has been instrumented to allow us to collect both seepage water and runoff water. We were able to examine how soil properties and crop operations effect the division of water between runoff and seepage, and how this effects the potential of fertilizer chemicals to be carried into water resources and become pollutants. We were able to show that wheel tracks in the soil are a major source of runoff water and pollution of water resources 'downstream'. The results will provide strong justification for managing wheel track runoff.

Technical Abstract: The Root Zone Quality Water Model (RZWQM) is a comprehensive one-dimensional field process model developed by USDA-ARS scientists for tracking the dynamics of water, pesticides, metabolites and nutrients in a climate/soil/crop system. We calibrated and validated the RZWQM (Version 3.2) in comparison with a two-year study of pesticide and nutrient fate and transport on a Cowarts loamy sand field (Watershed Z) at the Coastal Plain Experiment Station near Tifton, GA. Sweet corn (Zea Mays L.) and pearl millet (Panicum miliaceum L.) were grown in the spring and summer, respectively. Primary input data were daily weather and breakpoint rainfall data as well as crop management and tillage operations and fertilizer and pesticide applications. The model reasonably simulated soil water flows both on the surface and subsurface as well as nutrient transport into and out of the soil system. Standard practice for row crops in this region utilizes permanent beds and wheel tracks. We found that simulating the hydrology of the beds and wheel tracks separately, and then combining runoff and leaching weighted by area provides insights into potential BMP's for water quality conservation that a single lumped-parameter simulation obscures.

Last Modified: 11/21/2014
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