We Preserve Farmland
We Preserve Farmland
As great swaths of farmland change from pasturing cows to parking cars, and as green fields convert to gray pavement, maintaining well-managed farms in parts of the central Pennsylvania region—and restoring good water quality—become ever more difficult. The dollar value that urbanization often places on good farmland makes resisting such change harder every day. Yet saving farmland, and saving the countryside, is vitally important to our quality of life.
First, an acre of farmland—undeveloped— retains its rainwater filtration capacity. But an acre of development (even with just one house on it) never occurs alone, so filtration capacity in the area is soon compromised. Accompanying the one developed acre, with its one or two houses, are many more acres of supporting development, from new and expanded roads to shopping centers, parking lots, rooftops, schools, fire stations, recreation centers, and churches. In other words, there is always a multiplier of additional land use changes that accompanies development. These uses customarily cause an increase in the pollution running off the land, well above that of equivalent well-managed farmland.
Second, an acre of development permanently displaces an acre of the working landscape.
Farmland can always revert to forest. But developed land rarely, if ever, reverts to open land—it usually just becomes more intensively developed over time. Also, farmland can quite readily be managed to release much less nitrogen, phosphorus, and sediment pollution. (Urbanizing land can also be better managed; it’s just that it usually entails significant engineering and construction expense and low pollutant-removal efficiencies.) Low-density sprawl—one house per one or more acres—also increases the use of septic systems as the sewage treatment method of choice, and such systems can be responsible for a substantial amount of pollution.
Third, much of the forest land in the Chesapeake Bay watershed occurs in conjunction with farms. A quarter of the region’s farmland—more than 4.6M acres in three states—is forested.3 This natural land comprises about 25 percent of the total forest in Pennsylvania, Maryland, and Virginia.4 In addition, a significant proportion of farmland is managed in pasture or allowed to lie fallow at any given time, which produces some of the lowest nitrogen pollution loadings of any land use.
Fourth, conversion of farmland to urban/suburban land displaces natural habitat. An acre of lawn is a poor substitute for the wetlands, forests, pastures, and meandering headwater streams typically found among mid-Atlantic farmlands. Hundreds (or thousands) of acres of impervious surfaces created by development can actually endanger local habitat by heating streams and funneling fast-moving runoff into blown-out channels and sediment-choked shallows. These changes to the physical environment are permanent. Research has shown that as total imperviousness in a small watershed approaches 10 percent, stream water quality declines. As that percentage grows, so does stream degradation.
Finally, air pollution is a regular by-product of converting farmland to sprawl. Spread-out residential and commercial land uses on (former) farmland require people to use automobiles and trucks in an upward spiral that far outpaces the rate of population growth in an area. In the Chesapeake Bay region, emissions from transportation/ mobile sources account for a quarter to a third of the nitrogen pollution in the Bay.
First, an acre of farmland—undeveloped— retains its rainwater filtration capacity. But an acre of development (even with just one house on it) never occurs alone, so filtration capacity in the area is soon compromised. Accompanying the one developed acre, with its one or two houses, are many more acres of supporting development, from new and expanded roads to shopping centers, parking lots, rooftops, schools, fire stations, recreation centers, and churches. In other words, there is always a multiplier of additional land use changes that accompanies development. These uses customarily cause an increase in the pollution running off the land, well above that of equivalent well-managed farmland.
Second, an acre of development permanently displaces an acre of the working landscape.
Farmland can always revert to forest. But developed land rarely, if ever, reverts to open land—it usually just becomes more intensively developed over time. Also, farmland can quite readily be managed to release much less nitrogen, phosphorus, and sediment pollution. (Urbanizing land can also be better managed; it’s just that it usually entails significant engineering and construction expense and low pollutant-removal efficiencies.) Low-density sprawl—one house per one or more acres—also increases the use of septic systems as the sewage treatment method of choice, and such systems can be responsible for a substantial amount of pollution.
Third, much of the forest land in the Chesapeake Bay watershed occurs in conjunction with farms. A quarter of the region’s farmland—more than 4.6M acres in three states—is forested.3 This natural land comprises about 25 percent of the total forest in Pennsylvania, Maryland, and Virginia.4 In addition, a significant proportion of farmland is managed in pasture or allowed to lie fallow at any given time, which produces some of the lowest nitrogen pollution loadings of any land use.
Fourth, conversion of farmland to urban/suburban land displaces natural habitat. An acre of lawn is a poor substitute for the wetlands, forests, pastures, and meandering headwater streams typically found among mid-Atlantic farmlands. Hundreds (or thousands) of acres of impervious surfaces created by development can actually endanger local habitat by heating streams and funneling fast-moving runoff into blown-out channels and sediment-choked shallows. These changes to the physical environment are permanent. Research has shown that as total imperviousness in a small watershed approaches 10 percent, stream water quality declines. As that percentage grows, so does stream degradation.
Finally, air pollution is a regular by-product of converting farmland to sprawl. Spread-out residential and commercial land uses on (former) farmland require people to use automobiles and trucks in an upward spiral that far outpaces the rate of population growth in an area. In the Chesapeake Bay region, emissions from transportation/ mobile sources account for a quarter to a third of the nitrogen pollution in the Bay.
