Recursos alimentares e impactes ambientais da agricultura no ambiente Ecological Services Ecological Services Natural Capital Figure Croplands 14-3 Page 276 Croplands Economic Services Economic Services Help maintain water flow and Help soil infiltration maintain water flow and soil infiltration Provide partial erosion erosion protection protection Can build soil organic matter Can build soil organic matter Store atmospheric carbon Store atmospheric carbon Provide wildlife habitat for some species Provide wildlife habitat for some species Food crops Food crops Fiber crops Fiber crops Crop genetic resources Crop genetic Jobsresources Jobs
Produção agrícola mundial a produção de alimentos aumentou 2 ½ vezes; a produção per capita de alimentos aumentou e o preço dos alimentos caiu Calories per day per person 3,700 3,500 3,300 3,100 2,900 2,700 2,500 2,300 2,100 Figure 14-17 Developed countries Page 288 World Developing countries 1960 1970 1980 1990 2000 2010 2030 Year
Changes in food production under MA Scenarios Demand for food crops is projected to grow by 70 85% by 2050, and water withdrawals by 30-85% Food security is not achieved by 2050, and child undernutrition would be difficult to eradicate (and is projected to increase in some regions in some MA scenarios) Child undernourishment in 2050 under MA Scenarios 17% of total 4% 2% 6% 5% commercial energy use Crops Livestock Food processing Food distribution and preparation Food production
Problemas ambientais resultantes da agricultura Biodiversity Loss Loss and degradation of habitat from clearing grasslands and forests and draining wetland Fish kills from pesticide runoff Killing of wild predators to protect livestock Loss of genetic diversity from replacing thousands of wild crop strains with a few monoculture strains Soil Erosion Loss of fertility Salinization Waterlogging Desertification Problemas ambientais resultantes da agricultura (2) Air Pollution Greenhouse gas emissions from fossil Fuel issue Other air pollutants from fossil fuel use Pollution from pesticide sprays Water waste Aquifer depletion Water Increased runoff and flooding from land cleared to grow crops Sediment pollution from erosion Fish kills from pesticide runoff Surface and groundwater pollution from pesticides and fertilizers Overfertilization of lakes and slow-moving rivers from runoff of nitrates and phosphates from fertilizers, livestock wastes, and food processing wastes
Salinização e saturação do solo com água Evaporation Evaporation Transpiration Evaporation Waterlogging Less permeable clay layer Prevention Reduce irrigation Solutions Figure Soil Salinization 14-12 Page 283 Cleanup Flushing soil (expensive and wastes water) Not growing crops for 2-5 years Switch to salttolerant crops (such as barley, cotton, sugar beet) Installing underground drainage systems (expensive)
Erosão do Solo Colorado Kansas Dust Bowl Oklahoma New Mexico Texas MEXICO Where Eroded Soil Goes: Sediments Also Cause Environmental Problems Ways to slow erosion: Making Soil Sustainable Contour Plowing No-Till Agriculture Combination of farming practices that include not plowing the land and using herbicides to keep down weeds.
Advantages Reduces erosion Saves fuel Cuts costs Trade-Offs Figure 14-13 Page 284 Conservation Tillage Disadvantages Can increase herbicide use for some crops Holds more soil water Reduces soil compaction Allows several crops per season Does not reduce crop yields Reduces CO 2 release from soil Leaves stalks that can harbor crop pests and fungal diseases and increase pesticide use Requires investment in expensive equipment
(a) Terracing (b) Contour planting and strip cropping
(c) Alley cropping (d) Windbreaks
Trade-Offs Inorganic Commercial Fertilizers Easy to transport Easy to store Easy to apply Advantages Inexpensive to produce Help feed one of every three people in the world Without commercial inorganic fertilizers, world food output could drop by 40% Disadvantages Do not add humus to soil Reduce organic matter in soil Reduce ability of soil to hold water Lower oxygen content of soil Require large amounts of energy to produce, transport, and apply Release the greenhouse gas nitrous oxide (N 2 O) Runoff can overfertilize nearby lakes and kill fish Integrated Pest Management Control of agricultural pests using several methods together, including biological and chemical agents Goals: To minimize the use of artificial chemicals To prevent or slow the buildup of resistance by pests to chemical pesticides
Desertification Desertification is the deterioration of land in arid, semi- arid and dry sub humid areas due to changes in climate and human activities Can be caused by Poor farming practices Conversion of marginal grazing lands to croplands
Causes Overgrazing Deforestation Erosion Salinization Soil compaction Natural climate change Consequences Worsening drought Famine Economic losses Lower living standards Environmental refugees
Moderate Severe Very Severe Integrated Pest Management Control of agricultural pests using several methods together, including biological and chemical agents Goals: To minimize the use of artificial chemicals To prevent or slow the buildup of resistance by pests to chemical pesticides
Solutions Sustainable Agriculture High-yield polyculture Organic fertilizers Biological pest control Integrated pest management Irrigation efficiency Perennial crops Crop rotation Increase Use of more waterefficient crops Soil conservation Subsidies for more sustainable farming and fishing Decrease Soil erosion Soil salinization Aquifer depletion Overgrazing Overfishing Loss of biodiversity Loss of prime cropland Food waste Subsidies for unsustainable farming and fishing Population growth Poverty Figur 14
What Can You Do? Sustainable Agriculture Waste less food Reduce or eliminate meat consumption Feed pets balanced grain foods instead of meat Use organic farming to grow some of your food Buy organic food Compost your food wastes
Capture Fisheries 25% of commercially exploited marine fish stocks are overharvested (high certainty) Marine fish harvest declining since the late 1980s Trophic level of fish captured is declining in marine and freshwater systems Examples of nonlinear change Fisheries collapse The Atlantic cod stocks off the east coast of Newfoundland collapsed in 1992, forcing the closure of the fishery Depleted stocks may not recover even if harvesting is significantly reduced or eliminated entirely
Trade-Offs Aquaculture Highly efficient High yield in small volume of water Increased yields through crossbreeding and genetic engineering Can reduce overharvesting of conventional fisheries Little use of fuel Profit not tied to price of oil High profits Advantages Disadvantages Large inputs of land, feed, And water needed Produces large and concentrated outputs of waste Destroys mangrove forests Increased grain production needed to feed some species Fish can be killed by pesticide runoff from nearby cropland Dense populations vulnerable to disease Tanks too contaminated to use after about 5 years Solutions More Sustainable Aquaculture Reduce use of fishmeal as a feed to reduce depletion of other fish Improve pollution management of aquaculture wastes Reduce escape of aquaculture species into the wild Restrict location of fish farms to reduce loss of mangrove forests and other threatened areas Farm some aquaculture species (such as salmon and cobia) in deeply submerged cages to protect them from wave action and predators and allow dilution of wastes into the ocean Set up a system for certifying sustainable forms of aquaculture