Chapter 13 Food, Soil Conservation, and Pest Management
Soil- A renewable resource if maintained properly. Soil make-up How soil is formed… • Eroded rock • Mineral nutrients • Decaying organic matter • Water • Air • Microorganisms • Weathering • Physical • Wind, water, moving plates • Chemical • acids • Biological • Lichens, roots
Why is soil so important? • Nutrients needed by plants are in soil • Nutrients by humans are then taken up by plants or animals that get them from the soil • Water purifier • Removes carbon from the atmosphere and stores it as carbon compounds
Soil Layers • Soil horizons are viewed through a soil profile • O horizon= surface litter • A horizon= topsoil and humus (partially decomposed plants and animals and clay, silt, and sand) • B horizon= subsoil • C horizon= parent rock • Bedrock
Which biome(s) is most often converted to cropland? • Why do you think this is the case?
Water movement through soil • Infiltration- Waters natural movement down through soil dissolving minerals and organic matter and carrying them lower as it moves- leaching
Soil properties: • Soil is composed of • Clay- smallest particle size • Silt- medium • Sand- larger • Loam is the best for plants. An even mixture of all three.
Soil properties continued… • Porosity or void fraction is a measure of the void (i.e., "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0–1, or as a percentagebetween 0–100%. • How much “space” is available to “hold” water.
What is permeability? • http://techalive.mtu.edu/meec/module06/Permeability.htm
The relationship between Porosity and Permeability • In some soils porosity and permeability have a direct relationship, as you have more pores water can flow through easier. • In some soils porosity and permeability have an indirect relationship, as you have more pores there are more places for water to get trapped thus decreasing the permeability. • It depends on medium type and compaction of the medium.
Core Case Study: What is Golden Rice? • http://www.youtube.com/watch?v=sbxA4WlkUP8
FOOD SECURITY AND NUTRITION • Global food production has stayed ahead of population growth. However: • One of six people in developing countries cannot grow or buy the food they need. • Others cannot meet their basic energy needs (undernutrition / hunger) or protein and key nutrients (malnutrition).
Food Challenges for the FUTURE: • 1)poverty • 2)making and moving enough food to sustain a growing population • 3)doing so sustainably (not degrading soil and water) • Use of fossil fuels in farming • Wastes from plants and animals • Erosion of the soil • Degradation of the minerals and vitamins from the soil • Polluting water by increasing fertilizer run-off, animal waste run-off
FOOD SECURITY AND NUTRITION • Food securitymeans that every person in a given area has daily access to enough nutritious food to have an active and healthy life. • Need large amounts of macronutrients (protein, carbohydrates, and fats). • Need smaller amounts of micronutrients (vitamins such as A,C, and E). • Food Security Act of 1985- subsidy for taking highly eroded land and planting it with grasses to restore soil.
FOOD SECURITY AND NUTRITION • One in three people has a deficiency of one or more vitamins and minerals, especially vitamin A, iodine (causes goiter - enlargement of thyroid gland), and iron (causes anemia). • Measles and diarrhea kill many children in developing countries. Figure 13-2
War and Corruption leading to Hunger • Starving children collecting ants to eat in famine-stricken Sudan, Africa which has been involved in civil war since 1983. • Money spent on weapons, manpower used for fighting, no stability, land maintained by rich only. Figure 13-3
Hunger from war… • http://www.youtube.com/user/WorldConcernVideos?v=q6gYK7474sE&feature=pyv
Solutions: Reducing Childhood Deaths from Hunger and Malnutrition • There are several ways to reduce childhood deaths from nutrition-related causes: • Immunize children. • Encourage breast-feeding. • Prevent dehydration from diarrhea. • Prevent blindness from vitamin A deficiency. • Provide family planning. • Increase education for women.
Overnutrition: Eating Too Much • Over nutrition and lack of exercise can lead to reduced life quality, poor health, and premature death. The same problems undernourished people face. • A 2005 Boston University study found that about 60% of American adults are overweight and 33% are obese (totaling 93%). • Americans spend $42 billion per year trying to lose weight. • $24 billion per year is needed to eliminate world hunger.
FOOD PRODUCTION • Croplands- grains, 77% of food on 11% of land • 50% of most people’s diet is based on grains • Rangelands- meat and cattle, 16% of food on 29% of land • Oceanic Fisheries and aquaculture- fish, 7% of food
Industrial Food Production: High Input Monocultures • About 80% of the world’s food supply is produced by industrialized agriculture. • Uses large amounts of fossil fuel energy, water, commercial fertilizers, and pesticides to produce monocultures. • Greenhouses are increasingly being used taking up natural flow of land. (can cause erosion issues) • Plantations are being used in tropics for cash crops such as coffee, sugarcane, bananas.
Industrialized agriculture Plantation agriculture Intensive traditional ag. Shifting cultivation Nomadic herding No agriculture Fig. 13-4, p. 275
Industrial Food Production: • Livestock production in developed countries is industrialized: • Feedlots are used to fatten up cattle before slaughter. • Most pigs and chickens live in densely populated pens or cages. • Most livestock are fed grain grown on cropland. • Systems use a lot of energy and water and produce huge amounts of animal waste. Lots of methane released (GHG).
What is the Japan-syndrome? • Industrialization Less people farming more $/person more meat wanted by people that now have more money more grain needed to feed animals less land to grow grain because more land needed for urbanization and livestock
Problems with sustainably growing enough food to sustain growing population: • Soil erosion and depletion of minerals • Water depletion and pollution from runoff • Overgrazing • Overfishing • Increased fuel costs • Increased atmospheric temperatures • ALL LEAD TO BIODIVERSITY LOSS DUE TO HABITAT LOSS AND RESOURCE DEGRADATION
Natural Capital Croplands Ecological Services Economic Services • Help maintain water flow and soil infiltration • Food crops • Provide partial erosion protection • Fiber crops • Can build soil organic matter • Crop genetic resources • Store atmospheric carbon • Jobs • Provide wildlife habitat for some species Fig. 13-6, p. 276
Is food production in the US efficient? Yes No • Food production doubled with no increase in land use since 1950. • Mostly due to genetic engineering • Net Energy Loss- 10 units of nonrenewable fossil fuels used to get 1 unit of food.
Traditional Agriculture: Low Input Polyculture—increasing crop yields • Many farmers in developing countries use low-input agriculture to grow a variety of crops on each plot of land, interplanting, through: • Polyvarietal cultivation: planting several genetic varieties of the same crop. • Intercropping: two or more different crops grown at the same time in a plot. Ex. Grain that uses Nitrogen and legume that puts it back into the soil.
Agroforestry: crops and trees are grown together. Trees provide shade and lower transpiration rate. • Polyculture: different plants are planted together and they mature at different times. Keeps ground covered with plants and reduces erosion.
Traditional Agriculture: Low Input Polyculture • Research has shown that, on average, low input polyculture produces higher yields than high-input monoculture. • Keeps soil fertile, helps with water purification. Figure 13-8
SOIL EROSION AND DEGRADATION • Soil erosion lowers soil fertility and can overload nearby bodies of water with eroded sediment. • Sheet erosion: surface water or wind peel off thin layers of soil. • Rill erosion: fast-flowing little rivulets of surface water make small channels. • Gully erosion: fast-flowing water join together to cut wider and deeper ditches or gullies.
Soil erosion problems and solutions: • http://www.youtube.com/watch?v=QT7hklD2l2M
Desertification: Degrading Drylands • About one-third of the world’s land has lost some of its productivity because of drought and human activities that reduce or degrade topsoil. • China’s dustbowl Figure 13-12
Salinization and Waterlogging • Repeated irrigation can reduce crop yields by causing salt buildup in the soil and waterlogging of crop plants. Figure 13-13
Solutions Soil Salinization Prevention Cleanup Reduce irrigation Flush soil (expensive and wastes water) Stop growing crops for 2–5 years Switch to salt-tolerant crops (such as barley, cotton, sugarbeet) Install underground drainage systems (expensive) Fig. 13-15, p. 281
Salinization and Waterlogging of Soils: A Downside of Irrigation • Example of high evaporation, poor drainage, and severe salinization. • White alkaline salts have displaced crops. Figure 13-14
INCREASE SOIL QUALITY AND CROP YIELDS BY… • Modern farm machinery can plant crops without disturbing soil (no-till and minimum tillage). • Conservation-tillage farming: • Increases crop yield. • Raises soil carbon content. • Lowers water use. • Lowers pesticides. • Uses less tractor fuel. • Downside-expensive machinery
INCREASE SOIL QUALITY AND CROP YIELDS BY… • Fertilizers can help restore soil nutrients, but runoff of inorganic fertilizers can cause water pollution. • Organic fertilizers: from plant and animal (fresh, manure, or compost) materials. • Commercial inorganic fertilizers: Active ingredients contain nitrogen, phosphorous, and potassium and other trace nutrients. • PLANT COVER CROPS • WINDBREAKS, ROTATE CROPS
What is the green revolution? • High input agriculture and produces more food per unit of land. • Use of pesticides • Use of irrigation • Use of fertilizers • Growing monocultures of genetically engineered plants • Keep ground covered all year long with different plants
THE GREEN REVOLUTION AND ITS ENVIRONMENTAL IMPACT • Lack of water, high costs for small farmers, and physical limits to increasing crop yields hinder expansion of the green revolution. • Since 1978 the amount of irrigated land per person has declined due to: • Depletion of underground water supplies. • Inefficient irrigation methods. • Salt build-up. • Cost of irrigating crops.
Biodiversity Loss Soil Air Pollution Human Health Water Loss and degradation of grasslands, forests, and wetlands Erosion Water waste Nitrates in drinking water Greenhouse gas emissions from fossil fuel use Aquifer depletion Loss of fertility Pesticide residues in drinking water, food, and air Salinization Increased runoff and flooding from cleared land Other air pollutants from fossil fuel use Waterlogging Desertification Fish kills from pesticide runoff Sediment pollution from erosion Contamination of drinking and swimming water with disease organisms from livestock wastes Greenhouse gas emissions of nitrous oxide from use of inorganic fertilizers Fish kills from pesticide runoff Killing wild predators to protect livestock Surface and groundwater pollution from pesticides and fertilizers Belching of the greenhouse gas methane by cattle Loss of genetic diversity of wild crop strains replaced by monoculture strains Bacterial contamination of meat Overfertilization of lakes and rivers from runoff of fertilizers, livestock wastes, and food processing wastes Pollution from pesticide sprays Fig. 13-18, p. 285
The Ideal Pesticide • The ideal pest-killing chemical has these qualities: • Kill only target pest. • Not cause genetic resistance in the target organism. • Disappear or break down into harmless chemicals after doing its job. • Be more cost-effective than doing nothing.
Pesticide Protection Laws in the U.S. • Government regulation has banned a number of harmful pesticides (DDT). • The Environmental Protection Agency (EPA), the Department of Agriculture (USDA), and the Food and Drug Administration (FDA) regulate the sales of pesticides under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA).
PROTECTING FOOD RESOURCES: PEST MANAGEMENT • Advantages and disadvantages of conventional chemical pesticides. Figure 13-28
Integrated Pest Management • Using a combination of BIOLOGICAL, CHEMICAL, AND PHYSICAL pest management. • Lower the use of pesticides • Reduce pest populations