HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (45) Citing Articles via Google Scholar Google Scholar Articles by Hanson, J. D. Articles by Shaffer, M. J. Search for Related Content PubMed Articles by Hanson, J. D. Articles by Shaffer, M. J. Agricola Articles by Hanson, J. D. Articles by Shaffer, M. J.

Calibrating the Root Zone Water Quality Model

USDA-ARS, Northern Great Plains Res. Lab., P.O. Box 459, Highway 6 South, Mandan, ND 58554-0459

K. W. Rojas and Marvin J. Shaffer

USDA-ARS, Great Plains Systems Research, 301 S. Howes, Fort Collins, CO 80522

^* Corresponding author (jon{at}mandan.ars.usda.gov).

Techniques to reliably calibrate computer models are needed before the models can be applied to help solve natural resource problems. The USDA-ARS Root Zone Water Quality Model (RZWQM) is a comprehensive simulation model designed to predict hydrologic and chemical response, including potential for ground-water contamination, of agricultural management systems. RZWQM Version 3.2 was calibrated and evaluated at sites in Iowa, Minnesota, Missouri, Nebraska, and Ohio as part of the Management Systems Evaluation Areas (MSEA) project and at a site near Sterling in northeastern Colorado. Soil horizon description and a description of the physical and hydraulic properties of the soil were required to initialize the model. Calibration for nutrient cycling involved adjusting the model coefficients for mineralization, infiltration, and denitrification. Initial N pool sizes were estimated using medium to long-term computer simulations. Maximum N uptake rate, plant respiration, specific leaf area, and the effect of age at the time of propagule development and senescence were used to calibrate the plant production and yield component. To match the observed results for soil water, N, and plant growth, an iterative approach for calibrating the model was followed. When done methodically, total biomass estimates were within 5%, yield estimates were within l0%, and N uptake was within 20% of field measurements. Calibration of the C and N dynamics module produced results that were generally within 20 to 50 kg ha^–1 of measured values for soil profile NO^–₃-N. Independent evaluations of the calibrated model focused on four indicator output variables related to plant growth-total biomass, yield, N uptake, and N in the soil profile. Predictions matched the observed data in most cases. The crop model is very sensitive to plant N content. Even small errors in simulating N uptake levels can result in substantial errors in estimates of yield and total aboveground biomass. The model predicted biomass and yield well on irrigated and most dryland management systems and adequately simulated crop variables at various positions along the landscape.

Received for publication December 2, 1996.

This article has been cited by other articles:

				Q. Fang, L. Ma, Q. Yu, R. W. Malone, S. A. Saseendran, and L. R. Ahuja Modeling Nitrogen and Water Management Effects in a Wheat-Maize Double-Cropping System J. Environ. Qual., October 23, 2008; 37(6): 2232 - 2242. [Abstract] [Full Text] [PDF]

				E. R. Bayless, P. D. Capel, J. E. Barbash, R. M. T. Webb, T. L. C. Hancock, and D. C. Lampe Simulated Fate and Transport of Metolachlor in the Unsaturated Zone, Maryland, USA J. Environ. Qual., May 1, 2008; 37(3): 1064 - 1072. [Abstract] [Full Text] [PDF]

				R. T. Cygan, C. T. Stevens, R. W. Puls, S. B. Yabusaki, R. D. Wauchope, C. J. McGrath, G. P. Curtis, M. D. Siegel, L. A. Veblen, and D. R. Turner Research Activities at U.S. Government Agencies in Subsurface Reactive Transport Modeling Vadose Zone J., November 20, 2007; 6(4): 805 - 822. [Abstract] [Full Text] [PDF]

				B. J. Allred, J. M. Bigham, and G. O. Brown The Impact of Clay Mineralogy on Nitrate Mobility under Unsaturated Flow Conditions Vadose Zone J., April 9, 2007; 6(2): 221 - 232. [Abstract] [Full Text] [PDF]

				J. A. Kozak, L. Ma, L. R. Ahuja, G. Flerchinger, and D. C. Nielsen Evaluating Various Water Stress Calculations in RZWQM and RZ-SHAW for Corn and Soybean Production Agron. J., June 27, 2006; 98(4): 1146 - 1155. [Abstract] [Full Text] [PDF]

				N. N. Das and B. P. Mohanty Root Zone Soil Moisture Assessment Using Remote Sensing and Vadose Zone Modeling Vadose Zone J., March 8, 2006; 5(1): 296 - 307. [Abstract] [Full Text] [PDF]

				C. Hu, S. A. Saseendran, T. R. Green, L. Ma, X. Li, and L. R. Ahuja Evaluating Nitrogen and Water Management in a Double-Cropping System Using RZWQM Vadose Zone J., March 8, 2006; 5(1): 493 - 505. [Abstract] [Full Text] [PDF]

				D. A. Abrahamson, D. E. Radcliffe, J. L. Steiner, M. L. Cabrera, J. D. Hanson, K. W. Rojas, H. H. Schomberg, D. S. Fisher, L. Schwartz, and G. Hoogenboom Calibration of the Root Zone Water Quality Model for Simulating Tile Drainage and Leached Nitrate in the Georgia Piedmont Agron. J., November 17, 2005; 97(6): 1584 - 1602. [Abstract] [Full Text] [PDF]

				S. D. Merrill, D. L. Tanaka, and J. D. Hanson Comparison of Fixed-Wall and Pressurized-Wall Minirhizotrons for Fine Root Growth Measurements in Eight Crop Species Agron. J., September 19, 2005; 97(5): 1367 - 1373. [Abstract] [Full Text] [PDF]

				S. S. Anapalli, D. C. Nielsen, L. Ma, L. R. Ahuja, M. F. Vigil, and A. D. Halvorson Effectiveness of RZWQM for Simulating Alternative Great Plains Cropping Systems Agron. J., July 13, 2005; 97(4): 1183 - 1193. [Abstract] [Full Text] [PDF]

				L. Schwartz and L. M. Shuman Predicting Runoff and Associated Nitrogen Losses from Turfgrass using the Root Zone Water Quality Model (RZWQM) J. Environ. Qual., January 1, 2005; 34(1): 350 - 358. [Abstract] [Full Text] [PDF]

				S. A. Saseendran, L. Ma, D. C. Nielsen, M. F. Vigil, and L. R. Ahuja Simulating Planting Date Effects on Corn Production Using RZWQM and CERES-Maize Models Agron. J., January 1, 2005; 97(1): 58 - 71. [Abstract] [Full Text] [PDF]

				S. A. Saseendran, D. C. Nielsen, L. Ma, L. R. Ahuja, and A. D. Halvorson Modeling Nitrogen Management Effects on Winter Wheat Production Using RZWQM and CERES-Wheat Agron. J., May 1, 2004; 96(3): 615 - 630. [Abstract] [Full Text] [PDF]

				A. Bakhsh, J. L. Hatfield, R. S. Kanwar, L. Ma, and L. R. Ahuja Simulating Nitrate Drainage Losses from a Walnut Creek Watershed Field J. Environ. Qual., January 1, 2004; 33(1): 114 - 123. [Abstract] [Full Text] [PDF]

				G. C. Heathman, P. J. Starks, and M. A. Brown Time Domain Reflectometry Field Calibration in the Little Washita River Experimental Watershed Soil Sci. Soc. Am. J., January 1, 2003; 67(1): 52 - 61. [Abstract] [Full Text] [PDF]

				S. D. Merrill, D. L. Tanaka, and J. D. Hanson Root Length Growth of Eight Crop Species in Haplustoll Soils Soil Sci. Soc. Am. J., May 1, 2002; 66(3): 913 - 923. [Abstract] [Full Text] [PDF]

				D. Wallach, B. Goffinet, J.-E. Bergez, P. Debaeke, D. Leenhardt, and J.-N. Aubertot Parameter Estimation for Crop Models: A New Approach and Application to a Corn Model Agron. J., July 1, 2001; 93(4): 757 - 766. [Abstract] [Full Text] [PDF]