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| Registros recuperados: 29 | |
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| Gassman, Philip W.; Williams, Jimmy R.; Wang, Xiuying; Saleh, Ali; Osei, Edward; Hauck, Larry M.; Izaurralde, R. Cesar; Flowers, Joan D.. |
| The Agricultural Policy Environmental eXtender (APEX) model was developed by the Blacklands Research and Extension Center in Temple, Texas. APEX is a flexible and dynamic tool that is capable of simulating a wide array of management practices, cropping systems, and other land use across a broad range of agricultural landscapes, including whole farms and small watersheds. The model can be configured for novel land management strategies, such as filter strip impacts on pollutant losses from upslope cropfields, intensive rotational grazing scenarios depicting movement of cows between paddocks, vegetated grassed waterways in combination with filter strip impacts, and land application of manure removal from livestock feedlots or waste storage ponds. A... |
| Tipo: Report |
Palavras-chave: APEX; Best management practices; Farm and watershed simulations; Soil carbon; Water quality; Environmental Economics and Policy. |
| Ano: 2009 |
URL: http://purl.umn.edu/49156 |
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| Bouzaher, Aziz; Shogren, Jason F.; Holtkamp, Derald; Gassman, Philip W.; Archer, David W.; Lakshminarayan, P.G.; Carriquiry, Alicia L.; Reese, Randall; Kakani, Dharmaraju; Furtan, William Hartley; Izaurralde, R. Cesar; Kiniry, James R.. |
| This report describes an integrated agro-ecological modeling system that was developed to assess the potential economic and soil erosion impacts of different agricultural policies for the Canadian prairie provinces of Alberta, Saskatchewan, and Manitoba. The system was constructed by linking erosion metamodels (response functions), based on multiple simulations of the USDA Erosion Productivity Impact Calculator (EPIIC), with a modified version of Agriculture Canada's Canadian Regional Agriculture Model (CRAM) denoted as RS-CRAM (resource sensitive CRAM). A summary of both the environmental and agricultural decision (RS-CRAM) components are presented, including a description of the modifications and enhancements that were made to CRAM. Results of policy... |
| Tipo: Conference Paper or Presentation |
Palavras-chave: Agricultural and Food Policy; Environmental Economics and Policy. |
| Ano: 1996 |
URL: http://purl.umn.edu/18660 |
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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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| Gassman, Philip W.; Hauck, Larry M.. |
| This paper briefly describes the environmental component of an integrated modeling system that has been developed for simulating the movement of nutrients (nitrogen and phosphorus) from dairy waste disposal fields through the Upper North Bosque River Watershed (UNBRW) stream network in Erath and Hamilton Countries, Texas, as part of the "Livestock and the Environment: A National Pilot Project" (NPP). The environmental component consists of the Agricultural Policy/Environmental eXtender (APEX) model and the Soil Water Assessment Tool (SWAT). The APEX model is designed to simulate the edge-of-field nutrient runoff and leaching loadings from the application of solid and liquid manure on dairy waste disposal fields that are subsequently routed through the... |
| Tipo: Working or Discussion Paper |
Palavras-chave: Environmental Economics and Policy. |
| Ano: 1996 |
URL: http://purl.umn.edu/18663 |
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| Secchi, Silvia; Jha, Manoj K.; Kurkalova, Lyubov A.; Feng, Hongli; Gassman, Philip W.; Kling, Catherine L.. |
| This study investigates the implications of treating different environmental benefits as the primary target of policy design. We focus on two scenarios, estimating for both of them in-stream sediment, nutrient loadings, and carbon sequestration. In the first, we assess the impact of a program designed to improve water quality in Iowa on carbon sequestration, and in the second, we calculate the water quality impact of a program aimed at maximizing carbon sequestration. In both cases, the policy instrument is the retirement of land from agricultural production. Our results, limited to the state of Iowa, and to the case of set-aside for water quality or carbon sequestration purposes, indicate that the amount of co-benefits depends on what indicators are used... |
| Tipo: Working or Discussion Paper |
Palavras-chave: Carbon sequestration; Co-benefits; Environmental benefits targeting; Iowa; Land set-aside; Water quality; Environmental Economics and Policy. |
| Ano: 2005 |
URL: http://purl.umn.edu/18353 |
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| Burkart, Michael R.; Gassman, Philip W.; Moorman, Thomas B.; Singh, Piyush. |
| Data from seven Management Systems Evaluation Areas (MSEA) were used to test the sensitivity of a leaching model, PRZM-2, to a variety of hydrologic settings common in the Midwest. Results of long-term simulations using regional and generalized input parameters produced ranks of leaching potential similar to those based on measurements. Atrazine leaching was simulated because the use of atrazine was prevalent in the MSEA studies and it frequently occurs in the region's groundwater. Short-term simulations used sit-specific soil and chemical coefficients. Generalized simulations used data available from regional soil databases and standardized coefficients. Accurate short-term simulations were precluded by lack of antecedent atrazine concentrations in... |
| Tipo: Working or Discussion Paper |
Palavras-chave: Environmental Economics and Policy. |
| Ano: 1998 |
URL: http://purl.umn.edu/18506 |
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| Gassman, Philip W.. |
| This paper presents the underlying assumptions and results for the Agricultural Policy/Environmental eXtender (APEX) model, which was applied within an integrated modeling system for the National Policy Program (NPP) environmental baseline simulations for the Upper North Bosque River Watershed (UNBRW), located in Earth County, Texas. The integrated modeling system consists of an economic model that is linked to an environmental component comprising the field-scale APEX and watershed-scale Soil Water Assessment Tool (SWAT) models. The environmental baseline simulations test and calibrate the complete environmental component, using monitoring data obtained during 1993-94 in the UNBRW. The economic model was not executed for the environmental baseline,... |
| Tipo: Working or Discussion Paper |
Palavras-chave: Environmental Economics and Policy. |
| Ano: 1997 |
URL: http://purl.umn.edu/18668 |
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| Jha, Manoj K.; Arnold, Jeffrey G.; Gassman, Philip W.. |
| The Raccoon River Watershed (RRW) in West-Central Iowa has been recognized as exporting some of the highest nitrate-nitrogen loadings in the United States and is a major source of sediment and other nutrient loadings. An integrated modeling framework has been constructed for the RRW that consists of the Soil and Water Assessment Tool (SWAT) model, the interactive SWAT (i_SWAT) software package, Load Estimator (LOADEST) computer program, and other supporting software and databases. The simulation framework includes detailed land use and management data such as different crop rotations and an array of nutrient and tillage management schemes, derived from the U.S. Department of Agriculture's National Resources Inventory databases and other sources. This paper... |
| Tipo: Working or Discussion Paper |
Palavras-chave: Calibration; Management practices; Raccoon River Watershed; SWAT; Resource /Energy Economics and Policy. |
| Ano: 2006 |
URL: http://purl.umn.edu/18455 |
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| Bouzaher, Aziz; Shogren, Jason F.; Holtkamp, Derald; Gassman, Philip W.; Archer, David W.; Lakshminarayan, P.G.; Carriquiry, Alicia L.; Reese, Randall; Furtan, William Hartley; Izaurralde, R. Cesar; Kiniry, James R.. |
| The interface between RS-CRAM and the environmental component of the integrated modeling system is described for crops, crop sequences, and management systems representative of western Canada. An experimentally designed set of EPIC simulations were performed to generate erosion output that was used to construct wind and water erosion metamodels (response functions). The results of the EPIC simulations indicate that wind and water erosion would be the dominant erosion problem over most of Saskatchewan and Manitoba. For Alberta, water erosion was predicted to be the dominant problem, except for the southern portion of the province. Erosion impacts were sensitive to tillage and cropping patterns. EPIC-predicted yields did not vary much across tillage, a... |
| Tipo: Working or Discussion Paper |
Palavras-chave: Agricultural and Food Policy; Environmental Economics and Policy. |
| Ano: 1995 |
URL: http://purl.umn.edu/18681 |
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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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| Registros recuperados: 29 | |
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