Agricultural and Forestry
Policies

For the past fifty years, agricultural and forestry progress policies and practices have reflected awareness of conservation goals and sustainable use for food and fiber production. Legislation and public-private partnerships have worked to protect a productive environment by creating incentives to reduce soil erosion on agricultural lands, enhance privately owned wildlife habitat, maintain wetlands, and improve water quality. Recent U.S. policies to improve forest conservation on both public and private lands now involve initiatives for reforestation and the sustained use of forest resources. Since fiscal year 1991, the President has annually requested sufficient funding through the U.S. government to support annual plantings of 970 million trees in rural areas and 30 million trees in urban areas to meet the President's goal of increasing reforestation by one billion trees per year in this decade. In 1991, over 25 million trees were planted or improved in urban areas alone. In 1992, nearly $20 million will be available to cost-share tree planting and improvements in rural areas. The federal government also cooperates with state foresters and private nonindustrial landowners to develop forest stewardship plans before harvesting their timber.

Recently, the U.S. government adopted the principle of ecosystem management for publicly owned forest lands and announced an end to clearcutting as a standard harvesting practice on those lands. The government also launched related research at 122 national forests and grasslands and at ten research centers across the nation focusing on ecosystem management. The conservation title of the 1985 Farm Bill changed

the priorities of U.S. federal soil and water conservation agencies, of their state and local program participants, and of farmers themselves through such programs as the Conservation Reserve Program, the Swampbuster provision, and the Sodbuster provision. The Food, Agriculture, Conservation, and Trade Act of 1990 (1990 Farm Bill) strengthened the 1985 provisions and provided farmers with incentives to prevent pollution through a long-term adoption of alternative farming methods, such as low-input sustainable agriculture.

To remain eligible for farm program benefits, farmers must develop and carry out approved conservation plans on highly erodible crop land. To date, the Soil Conservation Service has helped 1.3 million farmers develop conservation plans to protect 55 million hectares (135 million acres) of land. In 1991 farmers implemented 52 percent of their conservation plans, mostly by enrolling highly erodible land in the Conservation Reserve Program, which temporarily removes such crop land from production. In addition to reducing soil erosion, the program stabilized the use of agricultural chemicals and nutrients, thus having a positive impact on water quality and associated aquatic systems.

The Swampbuster provision of the 1985 Farm Bill amended in 1990 protects the environmental values of wetlands—including wildlife habitat, flood control, filtering of nutrients and toxics, and ground-water recharge— by outlawing the conversion of wetlands to crop land. The Farm Bill's Sodbuster provision reduced the incentive for converting grasslands and forests to crop production by requiring the use of conservation measures on all such converted land. The Super Sodbuster amendment of the bill prohibits participants in the Conservation Reserve Program from bringing newly purchased, highly erodible land into crop production.

ignatories of the Framework Convention on

Climate Change agreed to inventory and report their nations' human-related emissions of greenhouse gases by "sources" and removal of these emissions by "sinks." Before signing and ratifying the Convention, the United States had taken steps to fulfill this obligation. In 1991, at the request of the Intergovernmental Panel on Climate Change, the United States produced

an inventory of U.S. greenhouse gas sources and sinks for 1988 (U.S. Government 1991). This inventory relies on published U.S. government emissions data where available and is supplemented by calculations using U.S. data and the analytical methods of calculation proposed by an international group of experts (OECD 1991). The results, reported in this chapter, are preliminary and will be revised with improved information in 1993.

Scientists agree that human activities are emitting enough greenhouse gases to change the composition of the earth's atmosphere. Since preindustrial times (1750-1800), CO2 concentrations in the atmosphere have risen 25 percent. Over this same period, CH4 concentrations nearly doubled, while N2O concentrations increased by 8 percent. Furthermore, during the past few decades, until the Montreal Protocol took effect, CFC emissions have increased at least 4 percent a year. With the exception of CH, and some of the halocarbons (carbon compounds that include chlorine, bromine, fluorine, and iodine),1 the emission rates of most of these greenhouse gases have been steady or increasing over the past decade (IPCC 1992a).

As the largest economy in the world, the United States contributes a significant share to global greenhouse gas emissions. The gases in Table 7 are arranged from left to right in decreasing order of the importance of their contribution to radiative forcing.

*These figures only include emissions from burning of fossil fuels, cement production, and oil and gas production. They do not include net uptake or emissions due to land-use changes.

** IPCC has estimated CO2 emissions from tropical deforestation at 4,800 million metric tons.

+ These estimates do not come from measurements of emissions. They are the results of the U.S. Environmental Protection Agency's Integrated Assessment Model and Vintaging Model.

Carbon Dioxide

Globally, the burning of carbon-containing fossil fuels emits 20,000-24,000 million metric tons (MMTs) of CO2 (5.5-6.5 billion metric tons of carbon) each year (IPCC 1992a). Between 1950 and 1988, U.S. annu

Sources: IPCC 1992a; IPCC 1992b; U.S. Government 1991