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Chapter 8. Raising Land Productivity: Saving Soil and Cropland
The world's farmers are literally losing ground on two fronts—the loss of soil from erosion and the conversion of cropland to nonfarm uses, as described in Chapter 3. Both are well-established trends that reduce agricultural output, but since both are gradual processes, they are often not given the attention that they deserve.
The 1930s Dust Bowl that threatened to turn the U.S. Great Plains into a vast desert was a traumatic experience that led to revolutionary changes in American agricultural practices, such as the planting of tree shelterbelts—rows of trees planted beside fields to slow wind and thus reduce wind erosion. Perhaps the most lasting change is strip cropping, the planting of wheat on alternate strips with fallowed land each year. This permits soil moisture to accumulate on the fallowed strips, while the planted strips reduce wind speed and hence the wind erosion on the idled strips. The key to controlling wind erosion is to keep the land covered with vegetation as much as possible and to slow wind speeds at ground level.33
One of the time-tested methods of dealing with water erosion is terracing to reduce runoff. On land that is less steeply sloping, as in the midwestern United States, contour farming has also worked well.34
Another newer, highly effective tool in the soil conservation toolkit is conservation tillage, which includes both no tillage and minimum tillage. In conventional farming, land is plowed, disked, or harrowed to prepare the seedbed, seed is drilled into the soil with a planter, and row crops are cultivated with a mechanical cultivator two or three times to control weeds. With minimum tillage, farmers simply drill seeds directly into the soil without any preparation at all. Weeds are controlled with herbicides. The only tillage is a one-time disturbance in a narrow band of soil where the seeds are inserted, leaving the remainder of the soil undisturbed, covered by crop residues and thus resistant to both water and wind erosion.35
In the United States, where farmers during the 1990s were required to implement a soil conservation plan on erodible cropland to be eligible for commodity price supports, the no-till area went from 7 million hectares in 1990 to nearly 21 million hectares (51 million acres) in 2000, tripling within a decade. An additional 23 million hectares were minimum-tilled, for a total of 44 million hectares of conservation tillage. This total included 37 percent of the corn crop, 57 percent of soybeans, and 30 percent of the wheat. Outside the United States, data for crop year 1998-99 show Brazil using conservation tillage on 11 million hectares and Argentina with 7 million hectares. Canada, at 4 million hectares, rounds out the "big four." And now no-till farming is catching on in Europe, Africa, and Asia. In addition to reducing soil losses, minimum-till and no-till practices also help retain water and reduce energy use.36
The U.S. method of controlling soil erosion by both converting highly erodible cropland back to grassland and adopting conservation practices to reduce erosion offers a model for the rest of the world. In 1985, the U.S. Congress, with strong support from the environmental community, created the Conservation Reserve Program (CRP) to reduce soil erosion and control overproduction. The CRP aimed to put up to 45 million acres of highly erodible land into permanent vegetative cover under 10-year contracts. Under this program, farmers were paid to plant fragile cropland to grass or trees. The retirement of 35 million acres under the CRP, together with adoption of conservation practices on 37 percent of all cropland, reduced U.S. soil erosion from 3.1 billion tons in 1982 to 1.9 billion tons in 1997.37
Saving cropland is sometimes more difficult than saving the topsoil on the cropland. This is particularly the case when dealing with urban sprawl, where strong commercial forces have influence. With cropland becoming scarce, efforts to protect prime farmland from urban spread are needed everywhere. Here Japan is the model. It has successfully protected rice paddies even within the boundaries of Tokyo, thus enabling it to remain self-sufficient in rice, its staple food.38
In the United States, Portland, Oregon, provides another model. The state adopted boundaries to urban growth 20 years ago, requiring each community to project its growth needs for the next two decades and then, based on the results, draw an outer boundary that would accommodate that growth. Richard Moe, head of the National Trust for Historic Preservation, observes, "This has worked in Oregon because it forced development back to the city. Lot sizes are smaller. There is more density, which is made possible by mass transit. There has been a doubling of the workforce in downtown Portland over the last 20 years without one new parking lot, without one new parking space."39
Moe's point about Oregon draws attention to still another threat to the world's cropland, namely the automobile. In a land-hungry world, the time has come to reassess the future of the automobile and to design transportation systems that provide mobility for entire populations, not just affluent minorities, and that do this without threatening food security. When Beijing announced in 1994 that it planned to make the auto industry one of the growth sectors for the next few decades, a group of eminent scientists—many of them members of China's National Academy of Sciences—produced a white paper challenging this decision. They identified several reasons why China should not develop a car-centered transport system, but the first was that the country did not have enough land to both feed its people and accommodate the automobile.40
The scientists recommended that instead of building an automobile infrastructure of highways, roads, and parking lots, China should concentrate on developing state-of-the-art urban light-rail systems augmented by buses and bicycles. This would not only provide mobility for far more people than a congested auto-centered system, it would also protect cropland.41
There are many reasons to question the goal of building auto-centered transportation systems everywhere, including climate change, air pollution, and traffic congestion. But the loss of cropland alone is sufficient. Future food security now depends on restructuring transportation budgets—investing less in highway infrastructure and more in a land-efficient rail, bus, and bicycle infrastructure.
33. United Nations, "The Great North American Dust Bowl: A Cautionary Tale," Global Alarm Dust and Sandstorms from the World's Drylands (Bangkok: Secretariat of the U.N. Convention to Combat Desertification, September 2002), pp. 77-121.
34. R. Neil Sampson, Farmland or Wasteland (Emmaus, PA: Rodale Press, 1981), p. 242.
35. USDA, Natural Resources Conservation Service, CORE4 Conservation Practices Training Guide: The Common Sense Approach to Natural Resource Conservation (Washington, DC: August 1999); Rolf Derpsch, "Frontiers in Conservation Tillage and Advances in Conservation Practice," in D. E. Stott, R. H. Mohtar, and G. C. Steinhardt, eds., Sustaining the Global Farm, selected papers from the 10th International Soil Conservation Organization Meeting, at Purdue University and USDA-ARS National Soil Erosion Research Laboratory, 24-29 May 1999 (Washington, DC: 2001), pp. 248-54.
36. Conservation Technology Information Center, Purdue University, 2000 United States Summary, from 2000 National Crop Residue Management Survey, at www.ctic.purdue.edu/Core4/ CT/ctsurvey/2000/2000USSummary.html, updated 20 January 2002; no-till and minimum-till farming from FAO, Intensifying Crop Production with Conservation Agriculture, at www.fao. org/ag/ags/agse/Main.htm, viewed 20 May 2003.
37. USDA, ERS, Agri-Environmental Policy at the Crossroads: Guideposts on a Changing Landscape, Agricultural Economic Report No. 794 (Washington, DC: January 2001); USDA, Farm Service Agency Online, "History of the CRP," in The Conservation Reserve Program at www.fsa.usda.gov/ dafp/cepd/12logocv.htm, viewed 29 April 2003.
38. USDA, Foreign Agricultural Service, Grains: World Markets and Trade (Washington, DC: various years).
39. Richard Moe, President of the National Trust for Historic Preservation, speech on sprawl, 1999 Red Hills Spring Event Dinner, Tall Timbers Research Station, Tallahassee, FL, 24 March 1999.
40. Ding Guangwei and Li Shishun, "Analysis of Impetuses to Change of Agricultural Land Uses in China," Bulletin of the Chinese Academy of Sciences, vol. 13, no. 1 (1999).
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