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Registros recuperados: 29
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A Tale of Three Watersheds: Nonpoint Source Pollution and Conservation Practices across Iowa AgEcon
Schilling, Keith E.; Tomer, Mark D.; Gassman, Philip W.; Kling, Catherine L.; Isenhart, Thomas M.; Moorman, Thomas B.; Simpkins, William W.; Wolter, Calvin F..
Tipo: Journal Article Palavras-chave: Resource /Energy Economics and Policy; Q25.
Ano: 2007 URL: http://purl.umn.edu/94483
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Agricultural Policies and Soil Degradation in Western Canada: An Agro-Ecological Economic Assessment: Project Summary AgEcon
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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Agricultural Policies and Soil Degradation in Western Canada: An Agro-Ecological Economic Assessment: Report 3. The Integration of the Environmental and Economic Components AgEcon
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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Agricultural Policies and Soil Degradation in Western Canada: An Agro-Ecological Economic Assessment: Report 4. Modifications to CRAM and Policy Evaluation Results AgEcon
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..
Tipo: Working or Discussion Paper Palavras-chave: Agricultural and Food Policy; Environmental Economics and Policy.
Ano: 1996 URL: http://purl.umn.edu/18674
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Allocating Nutrient Load Reduction across a Watershed: Implications of Different Principles AgEcon
Feng, Hongli; Jha, Manoj K.; Gassman, Philip W..
A watershed based model, the Soil and Water Assessment Tool (SWAT), along with transfer coefficients is used to assess alternative principles of allocating nutrient load reduction in the Raccoon River watershed in central Iowa. Four principles are examined for their cost-effectiveness and impacts on water quality: absolute equity, equity based on ability, critical area targeting, and geographic proximity. Based on SWAT simulation results, transfer coefficients are calculated for the effects of nitrogen application reduction. We find both critical area targeting and downstream focus (an example of geographic proximity) can be more expensive than equal allocation, a manifestation of absolute equity. Unless abatement costs are quite heterogeneous across the...
Tipo: Conference Paper or Presentation Palavras-chave: Environmental Economics and Policy.
Ano: 2006 URL: http://purl.umn.edu/21131
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Calibration and Validation of SWAT for the Upper Maquoketa River Watershed AgEcon
Kanwar, Ramesh S.; Reungsang, Pipat; Jha, Manoj K.; Gassman, Philip W.; Ahmad, Khalil; Saleh, Ali.
A validation study has been performed using the Soil and Water Assessment Tool (SWAT) model with data collected for the Upper Maquoketa River Watershed (UMRW), which drains over 16,000 ha in northeast Iowa. This validation assessment builds on a previous study with nested modeling for the UMRW that required both the Agricultural Policy EXtender (APEX) model and SWAT. In the nested modeling approach, edge-of-field flows and pollutant load estimates were generated for manure application fields with APEX and were then subsequently routed to the watershed outlet in SWAT, along with flows and pollutant loadings estimated for the rest of the watershed routed to the watershed outlet. In the current study, the entire UMRW cropland area was simulated in SWAT, which...
Tipo: Working or Discussion Paper Palavras-chave: Calibration; Modeling; Nitrate; SWAT; Validation; Water quality; Resource /Energy Economics and Policy.
Ano: 2005 URL: http://purl.umn.edu/18440
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Carbon Sequestration, Co-Benefits, and Conservation Programs AgEcon
Feng, Hongli; Kling, Catherine L.; Gassman, Philip W..
Land retirement and other agricultural conservation actions contribute greenhouse gas offsets and water quality improvements and reduce erosion and nitrogen runoff. Shifting the programmatic focus to carbon would enhance C sequestration and reduce nitrogen runoff, but would likely increase erosion.
Tipo: Journal Article Palavras-chave: Environmental Economics and Policy.
Ano: 2004 URL: http://purl.umn.edu/94004
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CARBON SEQUESTRATION, CO-BENEFITS, AND CONSERVATION PROGRAMS AgEcon
Feng, Hongli; Kling, Catherine L.; Gassman, Philip W..
Land use changes to sequester carbon also provide "co-benefits," some of which (for example, water quality) have attracted at least as much attention as carbon storage. The non-separability of these co-benefits presents a challenge for policy design. If carbon markets are employed, then social efficiency will depend on how we take into account co-benefits, that is, externalities, in such markets. If carbon sequestration is incorporated into conservation programs, then the weight given to carbon sequestration relative to its co-benefits will partly shape these programs. Using the Conservation Reserve Program (CRP) as an example, we show that CRP has been sequestering carbon, which was not an intended objective of the program. We also demonstrate that more...
Tipo: Working or Discussion Paper Palavras-chave: Carbon sequestration; Co-benefits; Conservation Reserve Program; Environmental Economics and Policy.
Ano: 2004 URL: http://purl.umn.edu/18336
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CLIMATE CHANGE SENSITIVITY ASSESSMENT ON UPPER MISSISSIPPI RIVER BASIN STREAMFLOWS USING SWAT AgEcon
Jha, Manoj K.; Arnold, Jeffrey G.; Gassman, Philip W.; Gu, Roy.
The Soil and Water Assessment Tool (SWAT) model was used to assess the impacts of potential future climate change on the hydrology of the Upper Mississippi River Basin (UMRB). Calibration and validation of SWAT were performed on a monthly basis for 1968-87 and 1988-97, respectively; R2 and Nash-Sutcliffe simulation efficiency (E) values computed for the monthly comparisons were 0.74 and 0.65 for the calibration period and 0.81 and 0.75 for the validation period. The impacts of eight 20-year (1971-90) scenarios were then analyzed, relative to a scenario baseline. A doubling of atmospheric CO2 concentrations was predicted to result in an average annual flow increase of 35 percent. An average annual flow decrease of 15 percent was estimated for a constant...
Tipo: Working or Discussion Paper Palavras-chave: Climate change; Flow; Hydrology; Simulation; Spatial patterns; Watershed; Environmental Economics and Policy.
Ano: 2004 URL: http://purl.umn.edu/18419
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Comparison of Land Use Area Estimates from Three Different Data Sources for the Upper Mississippi River Basin AgEcon
Chinnisamy, Santhi; Gassman, Philip W.; Secchi, Silvia; Srinivasan, Raghavan.
This study presents the results of comparing land use estimates between three different data sets for the Upper Mississippi River Basin (UMRB). The comparisons were performed between the U.S. Department of Agriculture (USDA) Natural Resource Conservation Service (NRCS) National Resource Inventory (NRI), the U.S. Geological Survey (USGS) National Land Cover Data (NLCD) database, and a combined USDA National Agricultural Statistics Service (NASS) Agricultural Census – NLCD dataset created to support applications of the Hydrologic Unit Model for the U.S. (HUMUS). The comparison was performed for 1992 versions of the datasets because that was the only consistent year available among all three data sources. The results show that differences in land use area...
Tipo: Report Palavras-chave: Agricultural land; Cropland; HUMUS; Land use area estimates; NLCD; Non-agricultural land; NRI; UMRB; Water quality modeling.; Land Economics/Use; Research Methods/ Statistical Methods; Resource /Energy Economics and Policy.
Ano: 2008 URL: http://purl.umn.edu/6332
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Economic and Environmental Co-benefits of Carbon Sequestration in Agricultural Soils: Retiring Agricultural Land in the Upper Mississippi River Basin AgEcon
Feng, Hongli; Kurkalova, Lyubov A.; Kling, Catherine L.; Gassman, Philip W..
This study investigates the carbon sequestration potential and co-benefits from policies aimed at retiring agricultural land in the Upper Mississippi River Basin, a large, heavily agricultural area. We extend the empirical measurement of co-benefits from the previous focus on environmental benefits to include economic transfers. These transfers have often been mentioned as a co-benefit, but little empirical work measuring the potential magnitude of these transfers has previously been undertaken. We compare and contrast five targeting schemes, each based on maximizing different physical environmental measures, including carbon sequestration, soil erosion, nitrogen runoff, nitrogen leaching, as well as the area enrolled in the program. In each case, the...
Tipo: Working or Discussion Paper Palavras-chave: Carbon sequestration; Co-benefits; Co-effects; Economic transfers; Environmental benefits targeting; Upper Mississippi River Basin; Environmental Economics and Policy; Land Economics/Use.
Ano: 2005 URL: http://purl.umn.edu/18423
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ENVIRONMENTAL CONSERVATION IN AGRICULTURE: LAND RETIREMENT VERSUS CHANGING PRACTICES ON WORKING LAND AgEcon
Feng, Hongli; Kurkalova, Lyubov A.; Kling, Catherine L.; Gassman, Philip W..
The study develops a conceptual framework for analyzing the allocation of conservation funds via selectively offering incentive payments to farmers for enrolling in one of two mutually exclusive agricultural conservation programs: retiring land from production or changing farming practices on land that remains in production. We investigate how the existence of a pre-fixed budget allocation between the programs affects the amounts of environmental benefits obtainable under alternative policy implementation schemes. The framework is applied to a major agricultural production region using field-scale data in conjunction with empirical models of land retirement and conservation tillage adoption, and a biophysical process simulation model for the environmental...
Tipo: Working or Discussion Paper Palavras-chave: Conservation Reserve Program; Land retirement; Working land; Environmental Economics and Policy; Land Economics/Use.
Ano: 2004 URL: http://purl.umn.edu/18627
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Estimating Atrazine Leaching in the Midwest AgEcon
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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Evaluation of EPIC for Three Minnesota Cropping Systems AgEcon
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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Historical Development and Applications of the EPIC and APEX Models AgEcon
Gassman, Philip W.; Williams, Jimmy R.; Benson, Verel W.; Izaurralde, R. Cesar; Hauck, Larry M.; Jones, C. Allan; Atwood, Jay D.; Kiniry, James R.; Flowers, Joan D..
The development of the field-scale Erosion Productivity Impact Calculator (EPIC) model was initiated in 1981 to support assessments of soil erosion impacts on soil productivity for soil, climate, and cropping conditions representative of a broad spectrum of U.S. agricultural production regions. The first major application of EPIC was a national analysis performed in support of the 1985 Resources Conservation Act (RCA) assessment. The model has continuously evolved since that time and has been applied for a wide range of field, regional, and national studies both in the U.S. and in other countries. The range of EPIC applications has also expanded greatly over that time, including studies of (1) surface runoff and leaching estimates of nitrogen and...
Tipo: Working or Discussion Paper Palavras-chave: APEX; Carbon sequestration; Climate change; EPIC; Modeling; Soil erosion; Water quality; Research Methods/ Statistical Methods.
Ano: 2005 URL: http://purl.umn.edu/18372
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IMPACT OF WATERSHED SUBDIVISION LEVEL ON FLOWS, SEDIMENT LOADS, AND NUTRIENT LOSSES PREDICTED BY SWAT AgEcon
Jha, Manoj K.; Gassman, Philip W.; Secchi, Silvia; Gu, Roy; Arnold, Jeffrey G..
The size, scale, and number of subwatersheds can affect a watershed modeling process and subsequent results. The objective of this study was to determine the appropriate level of subwatershed division for simulating sediment yield. The Soil and Water Assessment Tool (SWAT) model with a geographic information system interface (AVSWAT) was applied to four Iowa watersheds that varied greatly in drainage area. Annual output was analyzed from each simulation, which was executed for 30 years using climatic data representing the 1970 to 2000 period. The optimal threshold subwatershed size of the total drainage area to adequately predict sediment yield was found to be around 3 percent. Decreasing the size of subwatersheds beyond this level does not significantly...
Tipo: Working or Discussion Paper Palavras-chave: AVSWAT; Modeling of sediment yield; SWAT; Soil and Water Assessment Tool; Threshold subwatershed size; Watershed subdivision; Resource /Energy Economics and Policy.
Ano: 2002 URL: http://purl.umn.edu/18487
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Optimal Placement of Conservation Practices Using Genetic Algorithm with SWAT AgEcon
Jha, Manoj K.; Rabotyagov, Sergey S.; Gassman, Philip W..
The effectiveness of conservation practices depends on their placement on the fields within the watershed. Cost-effective placement of these practices for maximum water quality benefits on each field requires comparing a very large number of possible land-use scenarios. To address this problem, we combine the tools of evolutionary algorithm with the Soil and Water Assessment Tool (SWAT) model and cost data to develop a trade-off frontier of least cost of achieving nutrient reductions and the corresponding locations of conservation practices. This approach was applied to the Raccoon River Watershed, which drains about 9,400 km2 of an intensive agriculture region in west-central Iowa. Applying genetic algorithm to the calibrated SWAT modeling setup produced...
Tipo: Working or Discussion Paper Palavras-chave: Genetic algorithm; Nutrient calibration; Raccoon River Watershed; SWAT.; Environmental Economics and Policy; Land Economics/Use.
Ano: 2009 URL: http://purl.umn.edu/52241
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Privatizing Ecosystem Services: Water Quality Effects from a Carbon Market AgEcon
Secchi, Silvia; Jha, Manoj K.; Kurkalova, Lyubov A.; Feng, Hongli; Gassman, Philip W.; Kling, Catherine L..
Tipo: Journal Article Palavras-chave: Resource /Energy Economics and Policy; Q25.
Ano: 2007 URL: http://purl.umn.edu/94484
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REGIONAL ESTIMATION OF SOIL CARBON AND OTHER ENVIRONMENTAL INDICATORS USING EPIC AND I_EPIC AgEcon
Gassman, Philip W.; Campbell, Todd D.; Izaurralde, R. Cesar; Thomson, Allison M.; Atwood, Jay D..
Computer models are important tools for assessing regional carbon sequestration and other environmental impacts of agricultural management practices. The Environmental Policy Integrated Climate (EPIC) model is a very flexible model that has been used to make a wide range of field- and regional-scale environmental assessments. Large regional-scale applications of EPIC and similar models can require thousands of runs, resulting in a huge data management task. To address this problem, the Center for Agricultural and Rural Development (CARD) has developed an interactive EPIC (i_EPIC) software package that provides an automated approach to executing large sets of EPIC simulations. Overviews of both the latest EPIC version and the i_EPIC software package are...
Tipo: Working or Discussion Paper Palavras-chave: Environmental indicators; Modeling; Regional analyses; Software interface; Soil carbon; Environmental Economics and Policy.
Ano: 2003 URL: http://purl.umn.edu/18647
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Sny Magill Watershed Modeling Project: Final Report AgEcon
Saleh, Ali; Gassman, Philip W.; Kling, Catherine L..
Replaced with revised version of paper 10/29/08.
Tipo: Working or Discussion Paper Palavras-chave: BMP; Land use; Modeling; Nutrient management; Water quality; Watershed; Resource /Energy Economics and Policy.
Ano: 2006 URL: http://purl.umn.edu/18666
Registros recuperados: 29
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