"Urban transport systems based on a combination of rail lines, bus lines, bicycle pathways, and pedestrian walkways offer the best of all possible worlds in providing mobility, low-cost transportation, and a healthy urban environment." –Lester R. Brown, Plan B 4.0: Mobilizing to Save Civilization.
Chapter 8. Restoring the Earth: Conserving and Rebuilding Soils
In reviewing the literature on soil erosion, references to the “loss of protective vegetation” occur again and again. Over the last half-century, we have removed so much of that protective cover by clearcutting, overgrazing, and overplowing that we are fast losing soil accumulated over long stretches of geological time. Preserving the biological productivity of highly erodible cropland depends on planting it in grass or trees before it becomes wasteland.
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, including the planting of tree shelterbelts (rows of trees planted beside fields to slow wind and thus reduce wind erosion) and strip-cropping, the planting of wheat on alternate strips with fallowed land each year. Strip-cropping permits soil moisture to accumulate on the fallowed strips, while the alternating planted strips reduce wind speed and hence erosion on the idled land. 23
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 of basic commodities. By 1990 there were some 14 million hectares (35 million acres) of highly erodible land with permanent vegetative cover under 10-year contracts. Under this program, farmers were paid to plant fragile cropland to grass or trees. The retirement of 14 million hectares under the CRP, together with the use of conservation practices on 37 percent of all cropland, reduced U.S. soil erosion from 3.1 billion tons to 1.9 billion tons during the 15 years between 1982 and 1997. The U.S. approach offers a model for the rest of the world. 24
Another tool in the soil conservation toolkit—and a relatively new one—is conservation tillage, which includes both no-till and minimum-tillage. Instead of the traditional cultural practices of plowing land, discing or harrowing it to prepare the seedbed, and then using a mechanical cultivator to control weeds in row crops, farmers simply drill seeds directly through crop residues into undisturbed soil, controlling weeds with herbicides. The only soil disturbance is the narrow slit in the soil surface 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. In addition to reducing erosion, this practice helps retain water, raises soil carbon content, and reduces energy use. 25
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 25 million hectares in 2004. Now widely used in the production of corn and soybeans, no-till has spread rapidly in the western hemisphere, covering 25 million hectares in 2006 in Brazil, 20 million hectares in Argentina, and 13 million in Canada. Australia, with 9 million hectares, rounds out the five leading no-till countries. 26
Once farmers master the practice of no-till, its use can spread rapidly, particularly if governments provide economic incentives or require farm soil conservation plans for farmers to be eligible for crop subsidies. Recent FAO reports describe the early growth in no-till farming over the last few years in Europe, Africa, and Asia. 27
Other approaches are being used to halt soil erosion and desert encroachment on cropland. Algeria, trying to halt the northward advance of the Sahara Desert, announced in December 2000 that it was concentrating its orchards and vineyards in the southern part of the country, hoping that these perennial plantings will halt the desertification of its cropland. In July 2005, the Moroccan government, responding to severe drought, announced that it was allocating $778 million to cancel farmers’ debts and to convert cereal-planted areas into less vulnerable olive and fruit orchards. 28
Sub-Saharan Africa faces a similar situation, with the desert moving southward all across the Sahel, from Senegal on the west coast to Djibouti on the east coast. Countries are concerned about the growing displacement of people as grasslands and croplands turn to desert. As a result, the African Union has launched the Green Wall Sahara Initiative. This plan, originally proposed by Olusegun Obasanjo when he was President of Nigeria, calls for the planting of 300 million trees on 3 million hectares of land, in a long band stretching across Africa. Senegal, which is currently losing 50,000 hectares of productive land each year, would anchor the green wall on the western end. Senegal’s Environment Minister Modou Fada Diagne says, “Instead of waiting for the desert to come to us, we need to attack it.” 29
China is likewise planting a belt of trees to protect land from the expanding Gobi Desert. This green wall, a modern version of the Great Wall, is projected to reach some 4,480 kilometers (2,800 miles) in length, stretching from outer Beijing through Inner Mongolia. In addition to its Great Green Wall, China is paying farmers in the threatened provinces to plant their cropland in trees. The goal is to plant trees on 10 million hectares of grainland, easily one tenth of China’s current grainland area. 30
In Inner Mongolia (Nei Monggol), efforts to halt the advancing desert and to reclaim the land for productive uses rely on planting desert shrubs to stabilize the sand dunes. And in many situations, sheep and goats have been banned entirely. In Helin County, south of the provincial capital of Hohhot, the planting of desert shrubs on abandoned cropland has now stabilized the soil on the county’s first 7,000-hectare reclamation plot. Based on this success, the reclamation effort is being expanded. 31
The Helin County strategy centers on replacing the large number of sheep and goats with dairy cattle, increasing the number of dairy animals from 30,000 in 2002 to 150,000 by 2007. The cattle are kept within restricted areas, feeding on cornstalks, wheat straw, and the harvest from a drought-tolerant forage crop resembling alfalfa, which is grown on reclaimed land. Local officials estimate that this program will double incomes within the county during this decade. 32
To relieve pressure on the country’s rangelands, Beijing is asking herders to reduce their flocks of sheep and goats by 40 percent. But in communities where wealth is measured in livestock numbers and where most families are living in poverty, such cuts are not easy or, indeed, likely, unless alternative livelihoods are offered to pastoralists along the lines proposed in Helin County. 33
The only viable way to eliminate overgrazing on the two fifths of the earth’s land surface classified as rangelands is to reduce the size of flocks and herds. Not only do the excessive numbers of cattle, and particularly sheep and goats, remove the vegetation, but their hoofs pulverize the protective crust of soil that is formed by rainfall and that naturally checks wind erosion. In some situations, the only viable option is to keep the animals in restricted areas, bringing the forage to them. India, which has successfully adopted this practice for its thriving dairy industry, is the model for other countries. 34
Protecting the earth’s soil also warrants a worldwide ban on the clearcutting of forests in favor of selective harvesting, simply because with each clearcut there are heavy soil losses until the forest regenerates. Thus with each subsequent cutting, productivity declines further. Restoring the earth’s tree and grass cover, as well as practicing conservation agriculture,
protects soil from erosion, reduces flooding, and sequesters carbon. It is one way we can restore the earth so that it can support the next generation.
23. Secretariat of the U.N. Convention to Combat Desertification, “The Great North American Dust Bowl: A Cautionary Tale,” Global Alarm Dust and Sandstorms from the World’s Drylands (Bangkok: 2002), pp. 77–121.
24. Jeffrey Zinn, Conservation Reserve Program: Status and Current Issues (Washington, DC: Congressional Research Service, 8 May 2001); USDA, Economic Research Service, Agri-Environmental Policy at the Crossroads: Guideposts on a Changing Landscape (Washington, DC: 2001).
25. 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.
26. Conservation Technology Information Center, Purdue University, “National Tillage Trends (1990–2004),” from the 2004 National Crop Residue Management Survey Data; FAO, Intensifying Crop Production with Conservation Agriculture, at www.fao.org/ag, viewed 20 May 2003; Brazil, Argentina, and Australia from Rolf Derpsch, no-tillage consultant, e-mails to J. Matthew Roney, Earth Policy Institute, 6 and 11 August 2007; Canada from Doug McKell, Soil Conservation Council of Canada, “No-till Census Data-Canada,” presented at meeting of Confederation of American Associations for the Production of Sustainable Agriculture, Bella Vista, Paraquay, 12–14 September 2007.
27. FAO, op. cit. note 26.
28. “ Algeria to Convert Large Cereal Land to Tree-Planting,” Reuters, 8 December 2000; Souhail Karam, “Drought-Hit North Africa Seen Hunting for Grains,” Reuters, 15 July 2005.
29. Godwin Nnanna, “Africa’s Message for China,” China Dialogue, 18 April 2007; International Institute for Sustainable Development, “African Regional Coverage Project,” Eighth African Union Summit—Briefing Note, vol. 7, issue 2 (Geneva: 7 February 2007), p. 8; Federal Republic of Nigeria, Ministry of Environment, “Green Wall Sahara Programme,” at www.greenwallsahara.org, viewed 17 October 2007.
30. Evan Ratliff, “The Green Wall of China,” Wired, April 2003; Wang Yan, “China’s Forest Shelter Project Dubbed ‘Green Great Wall’,” Xinhua News Agency, 9 July 2006; Sun Xiufang and Ralph Bean, China Solid Wood Products Annual Report 2002 (Beijing: USDA, 2002).
31. Author’s discussion with officials of Helin County, Inner Mongolia (Nei Monggol), 17 May 2002.
33. U.S. Embassy, Grapes of Wrath in Inner Mongolia (Beijing: May 2001).
34. India’s dairy industry from A. Banerjee, “Dairying Systems in India,” World Animal Review, vol. 79/2 (Rome: FAO, 1994).
Copyright © 2008 Earth Policy Institute