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Exercise 1 Famine: Who is the Culprit? Study the news articles (p.1 and p. 2) about famine in Africa. Try to list the causes of famine. Drought, wars, soil erosion, deforestation, land used for cash crops Among the causes, which ones are results of environmental degradation? Soil erosion What is the ultimate cause of these? Deforestation, cultivation on marginal land (unsuitable terraces and soil), poor cultivation methods, overgrazing, surface mining without adequate replanting. Identify the issue at stake. Population pressure demand for land, food and development loss of arable land Loss of arable land/Causes - demand of land for urban development, roads & waste disposal - less suitable new land available to open for farming - capacity of existing farmland to continue producing food declines 1. air and water pollution 2. acid rain 3. increased UV due to ozone depletion 4. soil erosion a threat to the increased food production that will be needed to support the increasing human population Exercise 2 The impact of soil degradation 2.1 Study p. 3 to p. 8 What are the causes and effects of soil erosion? CAUSES of soil erosion - deforestation - overcultivation by machine and chemical-intensive farming - cultivation on marginal land (land with unsuitable terrain and soil) - poor cultivation method - overgrazing - poorly managed irrigation - surface mining without adequate replanting EFFECTS of soil erosion: 1. silts up ports and waterways. 2. reduces reservoir storage. 3. water retention nutrients content and depth of soil decrease. 4. fish production and crop productivity decrease. 5. intensity of flooding increase. 6. intensified drought and famine. 7. living standard decline. Define desertification Summarize the world situation with regard to soil erosion and desertification. Desertification - world situation - UN in 1984 estimated that more than one-third of land is vulnerable - 1/4 has already been affected - 20 times increase in soil erosion in Africa - 7% of topsoil eroded per 10 years - 21 million hectares of land changed to deserts per year lost production valued $26 billion 2.5 What is the likely trend in the future and the associated consequences? Consequences - soil quality decreases: water retention, nutrients, depth of soil decreased decrease in crop and livestock productivity - soil washed and blown into rivers and seas by rain and by wind. - silts up ports and water ways - reduces reservoir storage - decrease in fish production - intensity of flooding and drought increases - change in local climate 2.6 Describe other reasons for soil degradation. Salinization - accumulation of salts from irrigation - affect 50-65 % of cropland Waterlogging - poor drainage - 10% of irrigated land affected Exercise 3 Solving the problem 3.1 Study the materials (p.9 to p.14) provide before the lesson. 3.2 Summarize the possible solutions and rank them in order of effectiveness and plausibility. SOLUTIONS - Education - Conserve forests - Aforestation, plant shelterbelts of trees around roads, cropland - Plant resilient grass cover - Better livestock husbandry e.g. even distribution of grazing; laws to regulate the rights to use grazing areas, rearing varieties of cattle and sheep that can survive drought and less grass. - better farming techniques e.g. terracing on hill slopes, drought resistant varieties of crops, crop rotation, agro-forestry, cultivate nitrogen-fixing plants e.g. bean and pea plants, using natural fertilizers, better irrigation and drainage systems. Draw up a list of problems which need to be addressed if desertification and its related food, water and economic problems are to be solved. PROBLEMS - soil erosion occurs gradually, the impact is not easy to acknowledge. - economic pressures override conservation concerns, especially in poor nations where populations are growing rapidly and farmers concern focus on current crop, not harvests 10/20 years ahead. - Lack of political commitment - government lack funds - lack of cooperation between scientists, policy makers and agriculturists Local and International Efforts 1977 - UN programme to combat desertification - little has been accomplished - failure to analyse and deal with the social and economic factors that lead to abuse of land Key to halting land degradation • local control of resources • villagers and nomadic herders usually lack the means and authority to take appropriate preventive steps CHINA – a successful example in Loess Plateau Short-term: - terraced eroding slopes of marginal land - converts some marginal land to tree crops and pasture for livestock - soil conservation – freeing the land with < 400mm rainfall from agriculture Long-term: land use plans by government and local monitoring councils (assessing potential productivity and suitability for the different kinds of land use). Education Results: cropland areas reduced by half (as half of the land is used for trees and animals) but crop production increased by two times Critically evaluate the validity of the statement “There is a conflict between producing sufficient food production and checking further desertification”.