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| Kramer, L.A.; Gassman, Philip W.; Chung, S.W.; Williams, Jimmy R.; Gu, R.. |
| The Erosion Productivity Impact Calculator (EPIC) model was validated using long-term data collected for two southwest Iowa watersheds in the Deep Loess Soil Region, which have been cropped in continuous corn Zea Mays L. under two different tillage systems (conventional tillage and ridge-till). The annual hydrologic balance was calibrated for both watersheds during 1988-94 by adjusting the runoff curve numbers and residue effects on soil evaporation. Model validation was performed for 1976-87, using both summary statistics (means or medians) and parametric and nonparametric statistical tests. The errors between the 12-year predicted and observed means or medians were less than 10 percent for nearly all of the hydrologic and environmental indicators, with... |
| Tipo: Working or Discussion Paper |
Palavras-chave: Resource /Energy Economics and Policy. |
| Ano: 1995 |
URL: http://purl.umn.edu/18399 |
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| Chung, S.W.; Gassman, Philip W.; Huggins, David R.; Randall, G.W.. |
| The Erosion Productivity Impact Calculator (EPIC) model was tested using four years of field data collected at a site near Lamberton, Minnesota, under three different crop rotations: continuous corn (Zea mays L.) or CC, soybean (Glycine max L.)-corn (SC), continuous alfalfa (Medicago sativa L.) or CA. The model was evaluated by comparing measured versus predicted subsurface drainage flow (tile flow), nitrate-nitrogen (NO3-N) loss in tile flow, residual NO3-N in the soil profile, crop N uptake, and yield. Initially, EPIC was run using standard Soil Conservation Service (SCS) runoff curve numbers (CN2) suggested for the soil type at the site. Two different SC runs were performed with a nitrogen fixation parameter denoted as parm(7) set at either 1.0 or 0.3,... |
| Tipo: Working or Discussion Paper |
Palavras-chave: Modeling; Water quality; Crop rotation; Tile drainage; Nitrate leaching; Fertilizer; Crop Production/Industries. |
| Ano: 2000 |
URL: http://purl.umn.edu/18479 |
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