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Simulating Nitrate Drainage Losses from a Walnut Creek Watershed Field
Author(s) -
Bakhsh A.,
Hatfield J. L.,
Kanwar R. S.,
Ma L.,
Ahuja L. R.
Publication year - 2004
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2004.1140
Subject(s) - drainage , environmental science , loam , tile drainage , hydrology (agriculture) , watershed , well drainage , dns root zone , soil water , water quality , agronomy , soil science , geology , soil salinity , ecology , geotechnical engineering , machine learning , biology , computer science
ABSTRACT This study was designed to evaluate the improved version of the Root Zone Water Quality Model (RZWQM) using 6 yr (1992–1997) of field‐measured data from a field within Walnut Creek watershed located in central Iowa. Measured data included subsurface drainage flows, NO 3 –N concentrations and loads in subsurface drainage water, and corn ( Zea mays L.) and soybean [ Glycine max (L.) Merr.] yields. The dominant soil within this field was Webster (fine‐loamy, mixed, superactive, mesic Typic Endoaquolls) and cropping system was corn–soybean rotation. The model was calibrated with 1992 data and was validated with 1993 to 1997 data. Simulations of subsurface drainage flow closely matched observed data showing model efficiency of 99% (EF = 0.99), and difference ( D ) of 1% between measured and predicted data. The model simulated NO 3 –N losses with subsurface drainage water reasonably well with EF = 0.8 and D = 13%. The simulated corn grain yields were in close agreement with measured data with D < 10%. Nitrogen‐scenario simulations demonstrated that corn yield response function reached a plateau when N‐application rate exceeded 90 kg ha −1 Fraction of applied N lost with subsurface drainage water varied from 7 to 16% when N‐application rate varied from 30 to 180 kg ha −1 after accounting for the nitrate loss with no‐fertilizer application. These results indicate that the RZWQM has the potential to simulate the impact of N application rates on corn yields and NO 3 –N losses with subsurface drainage flows for agricultural fields in central Iowa.