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Using a model as a management tool requires testing of the model against field-measured data prior to its application for solving natural resource problems. This study was conducted to test the Root Zone Water Quality Model (RZWQM98) using four years (1996 to 1999) of field-measured data to simulate the effects of different N-application rates on corn yields and nitrate-nitrogen (NO[3]-N) losses via subsurface drain water. Three N-application rates (low, medium, and high), each replicated three times, were applied to corn in 1996 and 1998 under a randomized complete block design at a tile-drained corn-soybean rotation field near Story City, Iowa. No N-fertilizer was applied to soybean in 1997 and 1999. Model calibration...
Seasonal time of switchgrass (Panicum virgatum L.) harvest affects yield and biofuel quality and balancing these two components may vary depending on conversion system. A field study compared fall and spring harvest measuring biomass yield, element concentration, carbohydrate characterization, and total synthetic gas production as indicators of biofuel quality for direct combustion, ethanol production, and gasification systems for generation of energy. Switchgrass yields decreased almost 40% (from about 7-4.4 Mg ha(-1)) in winters with above average snowfall when harvest was delayed over winter until spring. The moisture concentration also decreased (from about 35070 g kg(-1)) only reaching low enough levels for...
On the Westside of California's San Joaquin Valley, the discharge of subsurface agricultural drainage water (DW) is subject to strict environmental regulations due to its high selenium (Se) content and potential risks to wildlife. Re-use of sahne-sodic DW to irrigate salt-tolerant forage crops is attractive because it reduces the volume of DW requiring disposal and the land area affected by salinity, while producing forages to satisfy the large demand for animal feed resulting from rapid expansions in dairy and beef cattle operations in this area. The biomass production and nutritional quality of six forages ('Jose' tall wheatgrass, creeping wildrye, alkali sacaton, 'Alta' tall fescue, puccinellia and 'Salado/801S'...
Yields of winter wheat, silage maize and grain maize in the main arable areas of the European Union (E.U.) were calculated with a simulation model, WOFOST, using historical weather data and average soil characteristics. The sensitivity of the model to individual weather variables was determined.Subsequent analyses were made using climate change scenarios with and without the direct effects of increased atmospheric CO 2. The impact of crop management in a changed climate was also assessed. The various climate change scenarios used appear to yield considerably different changes in yield, both for each location and for the E.U. as a whole.
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Maple syrup is produced from the sap of sugar maple collected in the late winter and early spring. Native American tribes have collected and boiled down sap for centuries, and the tapping of maple trees is a cultural touchstone for many people in the northeast and Midwest. Because the tapping season is dependent on weather conditions, there is concern about the sustainability of maple sugaring as climate changes throughout the region. Our research addresses the impact of climate on the quantity and quality of maple sap used to make maple syrup. Sap was sampled at 6 sites across the native range of sugar maple over 2 years as part of the ACERnet collaboration. At each site we sampled 15-25 mature sugar maple trees,...
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These data (vector and raster) were compiled for spatial modeling of salinity yield sources in the Upper Colorado River Basin (UCRB) and describe different scales of watersheds in the Upper Colorado River Basin (UCRB) for use in salinity yield modeling. Salinity yield refers to how much dissolved salts are picked up in surface waters that could be expected to be measured at the watershed outlet point annually. The vector polygons are small catchments developed originally for use in SPARROW modeling that break up the UCRB into 10,789 catchments linked together through a synthetic stream network. The catchments were used for a machine learning based salinity model and attributed with the new results in these vector...
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Maple syrup is produced from the sap of sugar maple collected in the late winter and early spring. Native American tribes have collected and boiled down sap for centuries, and the tapping of maple trees is a cultural touchstone for many people in the northeast and Midwest. Because the tapping season is dependent on weather conditions, there is concern about the sustainability of maple sugaring as climate changes throughout the region. Our research addresses the impact of climate on the quantity and quality of maple sap used to make maple syrup. Sap was sampled at 6 sites across the native range of sugar maple over 2 years as part of the ACERnet collaboration. At each site we sampled 15-25 mature sugar maple trees,...
    map background search result map search result map Salinity yield modeling spatial data for the Upper Colorado River Basin, USA Sap Quantity at Study Sites in the Northeast Sap Quality at Study Sites in the Northeast Salinity yield modeling spatial data for the Upper Colorado River Basin, USA Sap Quantity at Study Sites in the Northeast Sap Quality at Study Sites in the Northeast