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Africa’s savannahs and shrublands have been assumed to provide a large area for the expansion of cropland with relatively little damage to the environment. Research now shows that conversion would be likely to have high carbon and biodiversity costs.

Debates about biofuels tend to focus separately on estimates of adverse effects on food security, poverty, and greenhouse gas (GHG) emissions driven by land-use change (LUC) ( 1 – 4 ). These estimates often rely on global agriculture and land-use models. Because models differ substantially in their estimates of each of these adverse effects ( 2 , 3 , 5 ), some argue that each individual effect is too uncertain to influence policy ( 6 , 7 ). Yet these arguments fail to recognize the trade-offs; much of the uncertainty is only about which adverse effects predominate, not whether adverse effects occur at all. Our analysis of the three major models used to set government policies in the United States and Europe suggests that ethanol policies in effect are relying on decreases in food consumption to generate GHG savings ( 1 ).

A zone of hypoxic and anoxic waters has become a dominant feature of the northern Gulf of Mexico. Nitrogen draining into the Gulf from the Mississippi Basin has been identified as the primary source of the problem. Reducing nitrogen loads from point and nonpoint sources in the basin is the primary goal of an action plan developed to address the problem. In this paper, we use data on point source dischargers and a model of the agriculture sector to examine whether the purchase of nitrogen reduction bcreditsQ from nonpoint sources would reduce the cost of nitrogen control if point sources are required to reduce nitrogen discharges. Results indicate that a substantial degree of credit trading could affect agricultural commodity prices, thereby affecting agricultural production outside the basin. D 2004 Elsevier B.V. All rights reserved.

Environmental indicators can be used to target public programs to provide a variety of benefits. Social scientists, physical scientists, and politicians have roles in developing indicators that reflect the demands of diverse interest groups. We review the US Department of Agriculture’s Conservation Reserve Program (CRP), the largest agricultural conservation program the United States, to determine how a set of environmental indicators were developed and used, and assess results of their application. The use of such indicators has helped the CRP increase and broaden the program’s environmental benefits beyond erosion reduction, which was the primary focus of early program efforts, to meet other demands. This case study provides an example about how integration and assessment for the purpose of managing public resources requires more than natural science disciplines. Social science can help explain how public values influence what information is collected and how it is interpreted. Examples are given to show how the indices used for the CRP integrated science, politics and social values. In the end, the environmental benefits index (EBI) used to target US$ 20 billion of CRP funds reflects compromises made between science and policy considerations. It is our intention that studying this index will yield ideas and understanding from the natural science community that develops ecosystem indices about how to better plug in to programs in the future.

Nutrient pollution is one of the major sources of water quality impairments in the U.S. Agriculture is a major source of nutrients. Two alternative strategies for reducing nutrient loads from cropland are to reduce fertilizer application rates and to filter nutrients coming off cropland with restored wetlands. These two approaches are evaluated in the Mississippi Basin, where nutrient loadings to the Gulf of Mexico have caused a large zone of hypoxic waters. Because of the easement and restoration costs of wetlands, a fertilizer standard was found to be more cost effective than restoring wetlands for achieving a water quality goal up to a particular level of total nitrogen loss reduction. Beyond this point, wetland restorations are more cost-effective.

Economic analysis can be a guide to determining the level of actions taken to reduce nitrogen (N) losses and reduce environmental risk in a cost-effective manner while also allowing consideration of relative costs of controls to various groups. The biophysical science of N control, especially from nonpoint sources such as agriculture, is not certain. Widespread precise data do not exist for a river basin (or often even for a watershed) that couples management practices and other actions to reduce nonpoint N losses with specific delivery from the basin. The causal relationships are clouded by other factors influencing N flows, such as weather, temperature, and soil characteristics. Even when the science is certain, economic analysis has its own sets of uncertainties and simplifying economic assumptions. The economic analysis of the National Hypoxia Assessment provides an example of economic analysis based on less than complete scientific information that can still provide guidance to policy makers about the economic consequences of alternative approaches. One critical value to policy makers comes from bounding the economic magnitude of the consequences of alternative actions. Another value is the identification of impacts outside the sphere of initial concerns. Such analysis can successfully assess relative impacts of different degrees of control of N losses within the basin as well as outside the basin. It can demonstrate the extent to which costs of control of any one action increase with the intensity of application of control.

Wetland protection is an issue of ongoing debate. Although it is widely agreed that wetland loss to agriculture has been declining in recent decades, the role of policy remains contentious. We analyze the effect of changes in wetland delineation rules that were proposed but rejected by Congress during the 1996 farm bill debate. Our research combines detailed, site-specific information on wetlands with a broader model of the agricultural economy. Using site-specific data, we analyze the potential agricultural profitability of a representative sample of actual wetlands. We estimate wetland acreage that would have been exempted from swampbuster and Section 404 of the Clean Water Act under the proposed delineation changes, the acreage of exempted wetland that could be profitably converted to crop production, and the associated commodity price, crop acreage, and farm income effects. We find that up to 82.7 million wetland acres would be exempted under the proposed delineation changes, of which as many as 12 million acres could be profitably converted to crop production. This conversion would have a dampening effect on commodity price and farm income. We conclude that (a accurately estimating the effect of resource policy depends critically on detailed information on resource quality and (b) commodity price and farm income effects imply that all agriculture producers—not only those who could expand cropland acreage through wetland drainage—have a stake in wetland policy.

Metropolitan agriculture is not homogeneous. This paper delves beneath metropolitan county averages using data on individual farms in the Northeast classified into three statistically distinct types. A small group of adaptive farms profit from intensive production on smaller acreage to accommodate themselves to the urban environment. Traditional farms have increased costs and pressures on their more extensive operations without compensating increases in revenue from better-adapted enterprises. A large group of recreational farms subsidize small-farm activities from nonfarm income. Operating characteristics of each farm type are presented and their importance to metropolitan agriculture is assessed. Implications for preserving farming and farmland in the Northeast are drawn.

Metadata only record Most prior studies have found that substituting biofuels for gasoline will reduce greenhouse gases because biofuels sequester carbon through the growth of the feedstock. These analyses have failed to count the carbon emissions that occur as farmers worldwide respond to higher prices and convert forest and grassland to new cropland to replace the grain (or cropland) diverted to biofuels. By using a worldwide agricultural model to estimate emissions from land-use change, we found that corn-based ethanol, instead of producing a 20% savings, nearly doubles greenhouse emissions over 30 years and increases greenhouse gases for 167 years. Biofuels from switchgrass, if grown on U.S. corn lands, increase emissions by 50%. This result raises concerns about large biofuel mandates and highlights the value of using waste products.

Agricultural pollution of the environment is jointly determined by economic decisions driving land use, production practices, and stochastic biophysical processes associated with agricultural production, land and climate characteristics. It follows that environmental and economic statistics, traditionally collected independently of each other, offer little insight into non-point pollutant loadings. We argue that effective policy development would be facilitated by integrating environmental and economic data gathering, combined with simulation modelling linking economic and biophysical components. Integrated data collection links economics, land use, production methods and environmental loadings. An integrated economic/biophysical modelling framework facilitates policy analysis because monetary incentives to reduce pollution can be evaluated in the context of market costs and returns that influence land use and production activity. This allows prediction of environmental and economic outcomes from alternative policies to solve environmental problems. We highlight steps taken to merge economic and biophysical modelling for policy analysis within the Economic Research Service of the United States Department of Agriculture. An example analysis of a policy to reduce agricultural nitrogen pollution is presented, with the economic and environmental results illustrating the value of linked economic and biophysical analysis.

Genetic engineering refers to the genetic modification of organisms by recombinant DNA techniques. By a precise alteration of a plant’s traits, genetic engineering facilitates the development of characteristics not possible through traditional plant breeding techniques. The genetic modifications considered in this chapter include herbicide tolerance and insect resistance.

U.S. agricultural conservation policy has focused on a range of potential policy instruments centered on voluntary approaches tied into Depression-era commodity programs. Entering the twenty-first century, conservation policy is at a crossroads between more coercive regulatory policies, more costly voluntary programs, and more facilitative market-oriented policies. What are the pitfalls, advantages, disadvantages, and tradeoffs along these paths?

US ethanol production should exceed 12 billion gallons by 2010, and EISA 2007 mandates 36 billion gallons by 2022, diverting one-third of corn to ethanol and 13% of soybean production to biodiesel. Increased demand will ricochet through other agricultural sectors and alter production patterns and land use in the Corn Belt. This paper discusses effects of biofuel expansion on land and water resources. While US ethanol production will have large effects on international land use, there will likely be conversion of grassland to row crops, increased use of nitrogen fertiliser and pesticides, and increases in soil erosion in the Midwest.

A linear-programming model of agriculture in the Chowan-Pasquotank river basin of North Carolina is used to analyze soil-erosion reduction strategies while holding pesticide loadings constant. Two forms of pesticide-exposure indexes, reflecting terrestrial and aquatic exposure, are used to aggregate the effects of pesticide applications for no-till and conventional till systems. Reductions in pesticide exposure are compatible with high levels of erosion control. Greater reductions of pesticide exposure with comparable levels of erosion control are achievable at relatively low cost. Such reductions imply shifts in cropping patterns and resource use, however.

Metropolitan areas officially defined by the U.S. Census Bureau now encompass 16 percent of land area in the United States, including 29 percent of all farms and almost 20 percent of harvested cropland. Agriculture has adapted to the urbanizing environment through the working of smaller farms, more intensive production, a focus on high-value crops and livestock, and greater off-farm employment. Such adaptations are further advanced in older metro counties than in newer ones. This article shows how the more dispersed settlement pattern in newer metropolitan areas, emerging environmental and lifestyle trends, and recent developments in agricultural policy and the agricultural economy favor the survival of metro farming.

Several problems that make it difficult to deal with water pollution from cropland are identified. The most immediate need is for a rational framework for determining where conservation programs can make an impact on eutrophication problems in reservoirs draining rural watersheds. This includes estimating the level of control that would be required for each local farm situation and the economic impacts for the planning area. A modeling approach is suggested for a planning area in Southeastern Pennsylvania.

A linear programing model is used to evaluate the economic feasibility of reducing phosphorus loads from cropland to levels that are expected to alter adequately the trophic conditions of a water supply reservoir. The model employs phosphorus buffer curves for distributing phosphorus losses between runoff and eroded soil. Phosphorus pollution reductions are estimated for conservation activities according to the amount of erosion control and phosphorus fertility status. The planning model is intended to provide the best available estimates of pollution control attainable with given budget outlays, as well as to allocate pollution control funds efficiently among watersheds. It also contains sufficient detail to suggest practices for each local soil that are consistent with water quality plans.

Under new federal programs, soil and water conservation practices are relied upon to make a major contribution to the control of nonpoint sources of water pollution. Economic efficiency is to be considered in selecting these practices. Although only an experimental program funding of $50 million has been appropriated, $400 million of Rural Clean Water Program funds in 1980 were authorized. The program is to be administered by the Secretary of Agriculture with the concurrence of the Administrator of the Environmental Protection Agency. Because its implementation may eventually necessitate major land use changes and capital investments as part of 5- to 10-year contracts with farmers, we examine how soil conservation plans can incorporate potential changes in market prices of crops.

Economic and environmental analyses of manure handling systems have implications for programs to regulate agricultural nonpoint sources of water pollution and programs to subsidize manure handling practices. Previous economic analyses in the literature are discussed. Manure systems are evaluated in a consistent framework to determine construction and operating costs. The effect of soil type on nutrient conservation is examined for two hypothetical farms. Dissolved phosphorous runoff is estimated for the farms varying storage capacity and soil type. Costs of phosphorus reduction by handling system, housing type and soil type are examined. Conclusions for cost-sharing policy are drawn.

Farmer participation in a proposed 5,600 cow central digester facility is a function of herd size, present manure handling system, income tax effects and expectations about future changes in contract terms. The present value of net benefits from participation ranges from $6,000 to $6,400 for large herds and $3,200 for medium herds with manure storage. No net benefits accrue to medium sized herds not currently storing manure. Environmental impacts of the proposal will likely be positive for air and water quality but could reduce soil quality unless organic matter is returned to cropland.