Soil and Water Conservation Around the World Accelerated erosion is older than the recorded history Common cause of soil deterioration all over the world is erosion Soil erosion has been severe from earliest civilizations in the Middle East to the most recently cultivated lands in Americas Australia and southern Africa Soil Deterioration A few civilizations have developed and used conservation measures that reduce soil deterioration and maintained soil productivity at satisfactory levels for many centuries In many new lands colossal productivity losses occurred in very short periods emphasized the urgency for conservation measures Soil Deterioration Soil deterioration has often been so great that the land has been abandoned because it is no longer productive Mankind has frequently failed to develop effective cultivation systems that maintain soil productivity over long periods Soil deterioration resulting from erosion has caused the decline of many civilizations Soil and water conservation practices Soil and water conservation practices are essential around the world to retain the productive base of agriculture needed to support rapidly increasing population Most countries have established some kind of conservation agency like NRCS Soil and water conservation practices Soil and water conservation practices Progress is uneven because of differences in culture soil and agriculture are so great that adaptation is necessary but usually has been inadequate Massive mechanization schemes as well as most temperate region techniques of soil management have failed in the tropics One reason is that most soils in the tropics when cropped continuously form surface crusts and become cloddy and crop yield soon decline below economic levels 1 Shifting cultivation Failures include Shifting cultivation is the traditional technique used in forested tropics to maintain yields and control the loss of soil and water 2 to 3 years of cultivation and 20 years of shrubs and trees Vertisols in the tropics are burned and cropped until yields decline and then rested in native grass to rejuvenate them Terracing and ridging on the contour have failed in many tropical and subtropical regions because of physical deterioration of the soils Also more rainfall Successful Techniques Most successful techniques of continuous cropping in the tropics have been the two soil management systems Maintain an organic surface mulch at all times no till Scientifically determine the major and minor nutrients required for each crop grown and supply them in the amounts needed at the times when the plants can absorb them Included incorporation of enough plant and animal residues to maintain suitable soil tilth What is the crisis The quiet crisis is the loss of topsoil and its effects Even in the US soil loss exceeds T for 44 of the cropland Depletion of topsoil could compromise economic progress and political stability more than the dwindling oil reserves Soil Erosion Quiet Crisis in the World Economy Brown and Wolf World watch paper no 60 What is causing the problem Food output has doubled in the last generation but some agricultural practices that have boosted food production have led to excessive soil erosion Rising population Rising affluence more corn for animal production What is the extent of the problem U S is the only major food producing country to make an inventory of soils and erosion CNI Conservation Needs Inventory of 1977 and 1982 showed little change in the 1 7 billion tons per year of soil loss Projected 10 decline in cropland per person 1964 2000 while the soil per person is projected to decline by 32 2 What are the dimensions of the problem Sediment load of selected major rivers Yellow River China 1 600 000 000 mt yr Ganges India 1 455 000 000 mt yr Mississippi River US 300 000 000 mt yr Erosion productivity Numerous cases put in terms of inches of soil loss vs bushels of corn loss ha or ac Reservoirs are filling up with sediments Egypt Aswan High Dam 139 000 000 mt yr Could fill up in 100 years Economics of conserving soil Conservation tillage No till Mobilizing public support One third work nation Kenya discovered that soil erosion is by far its most serious environmental problem Grass strips instead of terraces 1300 agricultural officers 3500 technical assistance 50 tree nurseries Terraces strips of grass Government Role Only government can calculate the longterm aggregate cost of soil erosion including off site capacity of irrigation reservoirs hydroelectric reservoirs water transport systems and recreation Information such as National Soil ErosionSoil Productivity Research Planning Committee Global balance sheet Agricultural products to liquid fuel Brazil 3 2 m acres of land to sugarcane for distillation into alcohol fuel corn for ethanol 1 5 acres of corn for fuel alcohol 1970 the fish harvest is declining Soils erosion will eventually lead to higher food prices hunger and quite possibly persistent pockets of famine 3 Africa is the unfolding global crises Soil Degradation and the future of agriculture in sub Saharan Africa Dr Rattan Lal suggests the problem is The rate of food production increase is one half the rate of population growth By the year 2000 the Sub Sahara Africa was facing a 22 million ton deficit of food Reasons for deficit Rapid population growth Socioeconomic factors Debt crisis Lack of appropriate agronomic research Low prices for agricultural produce Low rainfall Neglect misuse and mismanagement of natural resources Soil Degradation Implies a decline in soil quality and productivity through misuse or The reduction of the soils current or potential capacity to produce food feed and fiber crops as a result of one or more degradative processes The processes which cause physical biological and chemical deterioration The processes which cause physical biological and chemical deterioration Erosion 85 of land north of equator in Africa has a problem Desertification overgrazing wind erosion Laterization hard sheet of Fe and Al layers silica and sesquioxides Salt accumulation Excessive leaching Acidification Nutrient imbalance soil organisms decrease O M nutrients decrease highly weathered nitrogen decreases Compaction and crusting weak structure and decreasing O M and micro populations 4 Other complications Drought accentuating deterioration Temperature effects can get a high as 122 degrees F tops in the corn belt is 104 degrees F Are degraded soils reclaimable Must stop cycle of clearing and