UN Population Division, Department of Economic and Social Affairs,
with support from the UN Population Fund (UNFPA)
***************************************************************************** This document is being made available by the Population Information Network (POPIN) of the United Nations Population Division (DESIPA), in collaboration with the Population Programme Service, Women and Population Division of the Food and Agriculture Organization of the United Nations. For further information, please contact Mr. Jacques du Guerny, Chief of the Population Programme Service, via email: email@example.com ***************************************************************************** From: Population and Land Degredation. Rome: FAO, Women and Population Division, Population Programme Service, September 1995. ANNEX 1 FIGURE 4 THE EARTH LAND TOTAL AREA: 13 BILLION HECTARES *"Other land" includes barren and developed land. ================================================================ SOIL AS A CRITICAL NATURAL RESOURCE Soil-is much more than a simple medium for crop production. It is a dynamic ecosystem, a living membrane that cycles life- sustaining nutrients between bedrock and atmosphere. Good soils are home to some of the world's highest and most diverse Population of species, including earthworms, insects and microorganisms that help plants absorb nutrients and even protect against disease.23/ These organisms break down dead plant and animal tissue to form humus, the dark and crumbly carbon-based portion of soil. Healthy soils rich in humus soak up water, invite airflow and resist erosion. Humus- poor soils shed water, restrict root growth and break apart in rough weather. Soil ecosystems are threatened by the progressive loss of organic material as farmers abandon organic for chemical fertilizers and offer the land less fallow, or resting, time. Currently, however, little research is being conducted on the species composition and biological properties of soils. Soil may hold three times as much carbon as all the world's plants, 24/ but its carbon content is diminishing. Since the drawn of agriculture, an estimated 60 billion tons of soil carbon have risen from the soil to the atmosphere as climate-warming carbon dioxide. This amount is equivalent to a decade of global fossil fuel combustion at current rates.25/ Cultivated soils lose not only humus and organisms but also micronutrients needed for plant and human health. Fertilizers replace nitrogen, phosphorus and potassium in soils, but rarely much else. As crop after crop is reaped front the soil and shipped elsewhere, with little return of comparable organic material to the soil, there is no assurance that sufficient micronutrients will remain in the soil for future crops and future generations.26/, 27/ 23. Committee on International Soil and Water Research and Development, 1991. Toward Sustainability: Soil and Water Research Priorities for Developing Countries. Washington, DC: National Academy Press. 24. National Research council, 1993. Sustainable Agriculture and the Environment in the Humid Tropics. Washington, Dc: National Academy Press. 25. Kevin G. Harrison, Wallace S. Broecker and Georges Bonani 1993. "The Effect of Changing Land Use on Soil Radiocarbon". Science, vol. 262 (October 29). 26. Margaret R. Biswas, 1994. "Agriculture and Environment: A Review, 1972-1992." Ambio, vol. 23, No. 3 (May). 27. Judith McGuire, 1993. "Addressing Micronutrient Malnutrition." SCN News. No. 9, United Nations Administrative Committee on Coordination. Source: Engelman and LeRoy (1995). ====================================================================== ANNEX 2 Regional patterns of land degradation The extent of the degradation problem and its patterns vary notably among regions: - Africa has 25% of wasteland (the highest proportion among regions), 12% lightly or moderately degraded and 4% strongly or extremely degraded land (also the highest proportion). The main type of degradation by far is the loss of topsoil (76% of the degraded area) followed by the loss of soil nutrients (9%). Burkina Faso, Burundi, Ethiopia, Madagascar, Lesotho, Morocco and Rwanda are particularly affected. - North and Central America has 6% wasteland, 6% lightly or moderately degraded and 1% strongly degraded land. The main types of degradation are the loss of topsoil (75% of the degraded area) and terrain deformation from water erosion (16%, but 40% in Central America). Costa Rica, El Salvador and Panama are the most affected countries. - South America has 1% wasteland, 11% lightly or moderately degraded and 1% strongly or extremely degraded land. The main types of degradation are loss of topsoil from water erosion (39% of the degraded area), loss of soil nutrients (28%) and terrain deformation from water erosion (12%). Brazil is particularly affected. - Asia has 11% wasteland, 15% lightly or moderately degraded (the highest proportion among regions) and 3% strongly or extremely degraded land. Again the main type is loss of topsoil (71% of the degraded area), the next being terrain deformation (16%); salinization (7%) is significant. China, India, Thailand and Vietnam are particularly affected. - Australasia has 11% wasteland, 11% lightly or moderately degraded and a negligible proportion of strongly or extremely degraded land. For 95%, degradation consists in the loss of topsoil. - Europe has a negligible proportion of wasteland, 22% lightly or moderately degraded and 1% strongly or extremely degraded land. The main types of degradation are loss of topsoil from water erosion (61% of the degraded area) and compaction (15%). The table below quantifies the area not affected by degradation or wasteland, as a proportion of total land area, by region. Proportion of total area in stable and other terrain not degraded by human action, wasteland excluded, by region. --------------------------------------------------------- North America...... 91% WORLD.............. 74% South America...... 85% Asia............... 71% Australasia........ 78% Central America.... 62% Europe............. 77% Africa............. 59% --------------------------------------------------------- ========================================================================== Annex 3. THE CONSEQUENCES OF EROSION Source: FAO (1992). ===================================================================== ANNEX. 4 LIVESTOCK & ENVIRONMENT Livestock have been criticised for damaging the environment in a number of ways. However, the role of livestock as agents of environmental damage has often been misunderstood and, consequently, misrepresented. Current independent opinion based on research in the field presents a more balanced and positive view of livestock and their role in sustainable agriculture in developing countries. CRITICISM: "Demand for pasture has resulted in deforestation in the Amazon and Africa" * In Africa livestock are not important components of rainforest agricultural systems and it is rare in Africa and elsewhere for forests to be cleared for small scale livestock production. * Where forest has been cleared for livestock production, as in the Amazon, it has been by large companies responding to financial incentives to clear forest and re-seed with pasture. Often government and external finance has been involved and they must carry the blame, not livestock or small scale livestock producers. CRITICISM: "Overgrazing in semi-arid areas destroys vegetation and leads to desertification" * "Livestock have been charged with wholesale devastation of African rangelands and irreversible destruction of soils - desertification. Heavy grazing has changed vegetative cover, but has not seriously decreased the productivity of rangelands. The greatest threat to this region comes from human populations and expansion of cultivation. There is no solid evidence linking livestock to this process." (Winrock International Institute for Agricultural Development Report 1992) * "There are good scientific arguments for the case that pastures are more productive when they are grazed low - in other words when they appear more desert-like. Up to a point, plants produce more new and fresh growth if they are encouraged by being grazed, and they may be less vulnerable to drought if they are kept small." (Andrew Warren, University College, London. Report to U.N. 1991) CRITICISM: "Over-stocking of pastures and concentration of cattle around watering points accelerates soil erosion" * The two conventional wisdoms - that on the one hand livestock numbers have been rising for a long time, well beyond the calculated sustainable carrying and that on the other hand the productivity of rangelands has been falling for a long time - do not lie at all well together." (Ridley Nelson, senior researcher, World Bank working paper 1988) * "The view that cattle watering points act as centres or poles of desertification is now questioned. Only under extreme densities of cattle is soil erosion serious. Overgrazing has been greatly over-estimated as an environmental problem." (Andrew Warren, University College, London. Report to U.N. 1991) Where managed correctly the benefits of livestock to the environment and economy greatly outweigh any potential damage. Contributions to a healthy environment include the ability of livestock to utilize foliage and forage that grow on marginal land and to recycle many otherwise wasted products into high value products. LIVESTOCK & ENVIRONMENT Livestock in marginal lands Vast areas of the world are semi-arid or arid. Crop production is extremely risky or impossible and only grasses, shrubs and trees grow with any certainty. These provide grazing and browse to livestock, which are the only means of survival for millions of pastoralists. Traditionally pastoralists established complex systems of management which were sustainable. Given supporting services such as marketing, it is possible for pastoralists, through their livestock, to use arid -land vegetation and to convert it to valuable high quality products. Preventing erosion and adding fertility Where rainfall is sufficient, crops and fodder trees can be intercropped to mutual benefit. Fodder hedgerows planted on the contour provide forage for livestock and simultaneously protect the soil from wind and water erosion. Deep-rooted perennial species replenish soils with minerals from lower levels while leguminous trees provide nitrogen to soil and protein-rich feed. Where livestock are a risk to crop land they may be confined in stalls or yards and forage can be cut and carried to them. Manure from enclosed livestock is a valuable and convenient source of fertilizer. Livestock as source of pollution Livestock manure has been cited as a source of pollution but accumulation of excreta and contamination of groundwater with nitrites is primarily a problem with large-scale, intensive livestock systems. In smallholder systems, dung is valued as a fertilizer. Ruminant livestock (cattle, sheep and goats) produce methane as an end product of digestion. As a result ruminants have been criticised for contributing to the greenhouse effect and global warming. However, this must be seen in perspective: * Methane from ruminant digestion forms only some 2.5% of the total greenhouse gases: gas emissions from cars, power stations, industries and domestic fires are much greater * Emissions of methane from livestock have increased at a much slower rate in recent years than emissions from direct human activities. * It is possible to reduce the production of methane by a factor of 4 to 6 per unit of milk produced by feeding ruminant animal a nutritionally balanced diet. * Methane produced per unit of meat could be reduced by increasing meat production from non-ruminant species. Recycling through livestock Feeding crop residues to livestock and using their dung as fertilizer and soil conditioner benefits the environment directly. Soils treated with dung have better structure, water retention and draining capacity. As a result crops grow faster, providing good ground cover and erosion may be reduced. In practice, properly managed livestock have an integral role in sustainable agricultural systems in many developing countries. =================================================================== ANNEX. 5 Machakos: A Qualified Success Story With effort, farmland can be conserved and even improved as local population grows rapidly. This is the lesson offered by the 1.4 million-hectare Machakos district near Nairobi in Kenya. What is not clear, however, is that such conservation successes can be sustained indefinitely as populations continue to grow. A region of steeply sloping land that receives rare and erratic rainfall, Machakos was first settled by the Akamba people in the early part of the 20th century. By the 1930s, it had been severely degraded by overuse, with less than 5 per cent tree cover and soil erosion visible in 75 per cent of the inhabited area. Some observers predicted ecological collapse. Instead, the reverse happened. Over the next six decades, the population of Machakos expanded almost six-fold, to 1.4 million. Yet soil erosion decreased, tree cover increased, and the district moved closer to self-sufficiency in food. More people were talking better care of scarce, and therefore precious, land, even as they coaxed more production out of each hectare. Surprisingly high population densities may be compatible with sustainable land use under certain conditions. Within Machakos, many farmers were able to diversify their income by finding non-farm jobs, applying the additional income to land conservation. Education, land tenure, community-government partnerships and prominent leadership roles for women also enhanced conservation efforts.64 But this does not support the idea that population growth per se is good for land. The diversity of natural vegetation and wildlife in Machakos has declined, and local soils may also be deteriorating in quality, although only limited data is available. Key natural thresholds may eventually be exceeded in Machakos. The fact that yields and some indicators of soil quality improved between 1930 and 1990, despite the rapid population growth, demonstrates the capacities of committed and resourceful farmers. Yet this experience hardly suggests the district's human population could increase sixfold yet again and still improve yields and reduce soil erosion. Finding the balance between people and land remains a critical task.