Every summer, a large area forms in the northern Gulf of Mexico where dissolved oxygen becomes too low for many aquatic species to survive. This “hypoxic zone” is fueled by nutrient (nitrogen and phosphorus) runoff from the Mississippi/Atchafalaya River Basin (MARB), most of which comes from agriculture. This analysis used the ERS Regional Environment and Agriculture Programming (REAP) model and data from the USDA Conservation Effects Assessment Project (CEAP) to assess the most cost-effective way of achieving a 45-percent reduction in cropland nutrient loads to the Gulf. Strategies involve adoption of management practices that reduce nutrient loss from fields to water resources, off-field practices for intercepting nutrients, retirement of marginal cropland, and other changes in crop management. Results suggest that proximity to the Gulf was a major factor in the location of nutrient-reduction efforts when reducing Gulf hypoxia was the only goal. When local as well as Gulf nutrient-reduction targets are applied, nutrient-reduction efforts are spread more evenly across the MARB. Adopting nutrient management practices, restoring wetlands, and retiring cropland to meet water quality goals also increased commodity prices, resulting in more intensive production outside the MARB and increased nutrient and sediment loadings to water in other watersheds.

Dedicated energy crops, such as switchgrass in the United States, have received much attention as potential renewable feedstocks for liquid fuels or bioelectricity; however, markets do not presently exist for large-scale use of this resource. This study examines three policy scenarios that could create a market for bioelectricity using dedicated energy crops: a subsidy for bioelectricity generation, a national Renewable Portfolio Standard (RPS), and a national cap-and-trade policy to limit carbon dioxide (CO2) emissions. Model results suggest that energy crops as a share of total cropland by region would be greatest in the Northern Plains, Southeast, and Appalachia. Even though the impact of energy crop production on land use across scenarios is similar by design, the impacts on other model outputs are quite different, including the mix of electricity-generating technologies, the price of electricity, CO2 emissions, and the cost relative to a no-policy reference scenario. For example, the price of electricity increases with cap-and-trade but declines with a bioelectricity subsidy. In all scenarios, U.S. CO2 emissions decrease relative to the reference scenario. Emissions reductions are greatest in the cap-and-trade scenario, but significant reductions are also obtained with an RPS.

Reducing the size of the hypoxic zone (Dead Zone) in the northern Gulf of Mexico will require a significant reduction in nutrient loads from the Mississippi-Atchafalaya River Basin (MARB). This research uses an agriculture sector model and data on conservation system effectiveness and costs to estimate costs to the agriculture sector of meeting nutrient load goals at the outlet to the Gulf and at outlets of sub-basins in the watershed. The analysis also estimates resulting changes in crop prices and the resulting impacts on agricultural production and nutrient and sediment loss outside the MARB.

General circulation models predict significant and accelerating changes in local patterns of precipitation and temperature during the twenty-first century. Agriculture's vulnerability to climate change will depend on both the biophysical impacts of climate change on crop yields and on the agricultural system's ability to adapt to changing production conditions. Shifts in the extent and distribution of irrigated and dryland production are a potentially important adaptation response. Farmer flexibility to adapt may be limited, however, by changes in the availability of irrigation water under future climate conditions. This study uses a suite of models to explore the biophysical and economic impacts of climate change on U.S. fieldcrop production under several potential future climate projections, and to explore the potential limits and opportunities for adaptation arising from shifting regional water balances. The study findings suggest that, while irrigation shortages attributable to climate change have varying effects on cropland use, the aggregate impacts on national production are small relative to the direct biophysical impacts of climate change on yield.

U.S. agriculture faces significant changes in local patterns of precipitation and temperature over the next century, with implications for regional water cycling and water availability. The effects of climate change on food production, farmer livelihoods, and consumer welfare will depend on the direction, magnitude, and rate of change in local weather conditions, as well as on the ability of the agricultural sector to adapt to changing yield and productivity patterns, production costs, and resource availability. Of particular interest is whether producer adaptation is limited, or even enhanced, by regional changes in water availability for irrigation. This analysis focuses on cropping allocations and shifts in irrigated and dryland crop area as two potential responses to climate change in U.S. fieldcrop production. Despite higher temperatures and much regional variation in production response, U.S. irrigated fieldcrop acreage and water used for irrigation tend to decline with long-term climate change. Driving the decline in water use are changes in crop growth due to temperature stress, changes in growing-season precipitation, and shifts in surface-water supply availability. Changes in the relative profitability of dryland and irrigated agriculture will increase irrigation demand in some major irrigated regions and reduce demand in others.

Mathematical programming has long been an important tool for electric utility planners. This paper presents a survey of state-of-the-art mathematical programming methods as applied to electric power capacity expansion planning. The focus is on modelling features which make it possible to investigate important power system issues such as reliability, uncertainty and environmental impacts which linear programming models cannot address without considerable simplification. Solution methodologies are also described.

Global climate models predict increases over time in average temperature worldwide, with significant impacts on local patterns of temperature and precipitation. The extent to which such changes present a risk to food supplies, farmer livelihoods, and rural communities depends in part on the direction, magnitude, and rate of such changes, but equally importantly on the ability of the agricultural sector to adapt to changing patterns of yield and productivity, production cost, and resource availability. Study findings suggest that, while impacts are highly sensitive to uncertain climate projections, farmers have considerable flexibility to adapt to changes in local weather, resource conditions, and price signals by adjusting crops, rotations, and production practices. Such adaptation, using existing crop production technologies, can partially mitigate the impacts of climate change on national agricultural markets. Adaptive redistribution of production, however, may have significant implications for both regional land use and environmental quality.

This report considers how increased commodity prices might influence enrollment in and benefits from the Conservation Reserve Program (CRP) using two complementary models: a likely-to-bid model that uses National Resources Inventory data to simulate offers to the general signup portion of the CRP and an opt-out model that simulates retention of current CRP contracts. Under several higher crop price scenarios, including one that incorporates 15 billion gallons of crop-based biofuels production, maintaining the CRP as currently configured will lead to significant expenditure increases. If constraints are placed on increasing rental rates, it might be possible to meet enrollment goals with moderate increases in CRP rental rates — but this will mean accepting lower average Environmental Benefits Index scores as landowners with profitable but environmentally sensitive lands choose not to enroll.

How might increases in commodity prices, along with the acreage reduction mandated in the 2008 Farm Act, impact the Conservation Reserve Program (CRP)? Modeling Strategy The Likely To Bid (LTB) model “restarts” the CRP from scratch. Uses National Resources Inventory data to find parcels “likely” to offer acreage to the CRP Policy scenarios We consider several scenarios, both with and without increases in CRP rental rates. Continuation of current prices, which are well above prices prevalent when most CRP contracts were enrolled Predicted prices due to an increase in biofuels production to 15 billion gallons Expectation that summer 2008 prices will be the norm Findings Continuation of current, relatively high commodity prices would have noticeable impacts on the costs and environmental benefits of the CRP Additional impacts due to increasing ethanol production (from 6.5 to 15 billion gallons) would be relatively minor Additional impacts of a recurrence of summer 2008 prices would be substantial

Crop residues from agricultural field crops represent a potential source of vegetative (cellulosic) matter to be used in ethanol production. Crop residues may be particularly attractive if technologies for producing cellulosic ethanol become viable before dedicated crops, such as switchgrass, are commercially available. However, crop residues are not “free goods”—they provide soil nutrients and organic matter and help control erosion and retain moisture on cropland. Thus, the costs of shifting from production of corn-based ethanol to production of cellulosic ethanol from crop residues may offset the benefits. The Federal renewable fuel standards (RFS) call for annual U.S. production of 15 billion gallons of corn-based ethanol and 3 billion gallons of cellulosic ethanol in 2015 (see “Full Throttle U.S. Ethanol Expansion Faces Challenges Down the Road,” September 2009 Amber Waves). ERS estimated the landuse and resource effects if the U.S. produced 12 billion gallons of corn-based ethanol and 6 billion gallons of cellulosic ethanol from crop residue rather than the RFS target amounts. This scenario is not a projection, but serves to illustrate the tradeoffs between corn ethanol and cellulosic ethanol that may be faced as economically viable cellulosic technologies emerge. Under this scenario, total U.S. crop acreage would decline as cellulosic ethanol production displaces corn-based ethanol production. However, the aggregate environmental benefits of the shift may be smaller than expected because additional fertilizer would be applied to cropland to replace the nutrients removed with the harvested residue. The environmental effects of changes in planted acreage and crop mix would vary by region. With cellulosic production displacing 3 billion gallons of corn-based ethanol, nitrogen runoff to surface water would be reduced, while nitrogen leaching to groundwater would increase. Total nitrogen use would decrease in most regions, although a large increase would be expected in the Corn Belt due to the additional fertilizer needed to offset residue harvest and the small reduction in corn acres planted relative to that of the rest of the country. The study’s findings suggest, however, that crop residue harvest accompanied by changes in rotation and tillage management regimes could contribute to a net reduction in soil erosion. If cellulosic production displaces corn ethanol, acres planted to continuous corn would likely decline, particularly in the Corn Belt, while the use of no-till systems would expand. Wider adoption of no-till would be driven by the economic value of crop residues, as more can be harvested from no-till systems, which also reduce soil erosion.

Volatile petroleum prices, along with Federal policies aimed at reducing U.S. dependency on oil imports and mitigating climate change, have sparked rapid growth in biofuel demand. In response, production of agricultural commodities that serve as feedstock for biofuels has increased. Federal policy initiatives and private-sector investment point to continued growth in biofuel production and, consequently, increased demand for agricultural products. The Energy Independence and Security Act (EISA) of 2007 includes provisions for a Renewable Fuel Standard (RFS) to increase the supply of alternative fuel sources by requiring fuel producers to use at least 36 billion gallons of biofuel by 2022. The RFS provision establishes a level of 15 billion gallons of conventional ethanol by 2015 and at least 21 billion gallons of cellulosic (noncornstarch) ethanol and advanced biofuels (including ethanol from sugarcane and biodiesel) by 2022. The share of total domestic corn production supplying the ethanol market grew from 7.5 percent in 2001 to 22.6 percent in Federal mandates for biofuel production promote expanded crop acreage and shifts in cropping patterns and livestock production due to higher prices for corn and other grain crops.