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Food and Agriculture Objectives Describe world food supplies and some causes of chronic hunger and acute food shortages Differentiate between famine and chronic hunger and understand the role of natural disasters and social or economic forces in food shortages Explain some major nutritional requirements as well as the consequences of deficiencies in those nutrients Discuss some important characteristics of soil Objectives Differentiate between the sources and effects of land degradation Explain the need for water, energy and nutrients for sustained crop production Appreciate the benefits of pest control Understand some of the problems with pesticide use Explain alternative methods of pest control Analyze some of the promise and perils of genetic engineering Recognize the potential for low-input, sustainable, regenerative agriculture Chronic hunger In 1960, 60% population of developing countries were considered chronically undernourished – Unable to obtain 2200 kcal/day – Fallen to less than 15% Food supply By 2030, there will be enough food to provide each person with 3,050/day (more than we need) Poverty is the greatest threat to food security – Food security is the ability to obtain sufficient food on a daily basis – Women and children often get poorest diet Risk of inadequate nutrition Acute food shortages Famines are characterized by large-scale food shortages, massive starvation, social disruption, and economic chaos – Mass migrations often occur because productive capacity has been sacrificed – Environmental conditions are immediate trigger, but politics and economics are often underlying problems Famines Aid policies of rich countries often serve to distribute surplus commodities and produce feeling of generosity – Food camps have serious drawbacks: • Stress and crowding • Lack of sanitation • Close contact to epidemic diseases Malnutrition Malnourishment - Nutritional imbalance caused by a lack of specific dietary components Obesity The most common dietary problem in wealthy countries is over-nutrition – According to U.S. Surgeon General: • 64 of Americans are overweight – 33% are obese Nutritional problems Iron deficiency is the most common dietary imbalance in the world – Leads to anemia (low hemoglobin levels in the blood) • Increases risk of death from hemorrhage in childbirth • Affects development • Found in: – Red meat – Eggs – Legumes – Green vegetables Protein deficiency diseases Kwashiorkor - “Displaced Child” - Occurs mainly in children whose diet lacks high-quality protein – Reddish-orange hair – Bloated stomach Protein deficiency diseases Marasmus - “To Waste Away” - Caused by a diet low in protein and calories – Very thin, shriveled Key food sources Three crops deliver majority of world’s nutrients: – Wheat, rice and corn • Potatoes, barley, oats and rye are staples in cool, moist climates • Cassava, sweet potatoes, and other roots and tubers are staples in warm wet climates Meat and dairy Distribution highly inequitable – More developed countries make up 20% of world population, but consume 80% of meat and dairy production • 60% of production occurs in lesser developed countries – 90% of grain grown in North America is used to feed livestock Confined animal feeding operations (CAFOs) Poses environmental risks – Local air and water pollution – Animal waste stored in open lagoons – Hormone and antibiotic use is high • Selection for resistant bacteria (will discuss this later) Seafood Seafood is an important protein source Since 1989, 13/17 major fisheries have declined or become commercially unsustainable Aquaculture is providing an increasing share of the world’s seafood Aquaculture Can have negative effects – Spread diseases – Destruction of habitats – Escape of invasive species – Release of feces Polyculture techniques can reduce negative impacts Soil Soil - A complex mixture of weathered minerals, partially decomposed organic materials, and a host of living organisms – At least 20,000 different soil types in the US • Vary due to influences of parent material, time, topography, climate, and organisms – Can be replenished and renewed • Very slow process Soil composition Soil exhibits wide range of organic content – Humus - Insoluble residue from partially decomposed plants and animals Activity of organisms living in soil helps create structure, fertility, and cultivation suitability Soil organisms Activity of organisms living in soil helps create structure, fertility, and cultivation suitability Mycorrhizal fungi Mycorrhizal symbiosis between plants roots and specific fungal species • An example of a mutualism – Plants provide organic compounds – Fungi provide inorganic nutrients, e.g. phosphorus Soil use Approximately 11% of the earth’s land area is currently in agricultural production – Land per person has shrunk from 0.38 ha/person in 1970 to 0.21 ha/person in 2002 • Projected to be 0.16 ha/person in 2030 Land Resources In developed countries, 95% of agricultural growth has been from altered agricultural practices (pesticides - fertilizer). – Less land cultivated in North America now than 100 years ago. Many developing countries are reaching limit of lands that can be exploited for agriculture without unacceptable social and environmental costs. Land degradation Generally, land is considered degraded when soil is impoverished or eroded, run-off is contaminated, or biodiversity is diminished • In Africa and Asia, 20% of land is moderately degraded • In Mexico and Central America, 25% of land is extremely degraded Causes include erosion, salinization, nutrient depletion, etc. Erosion Erosion is an important natural process Worldwide, erosion reduces crop production by equivalent of 1% of world cropland per year – Five tons per acre is the maximum tolerable rate of soil loss • Some farms lose soil at twice that rate Mechanisms of erosion Wind can equal or exceed water as an erosive force, especially in a dry climate and on flat land Intensive farming practices: • Row crops leave soil exposed • Weed free-fields • Removal of windbreaks • No crop-rotation or resting periods Water Water – Agriculture accounts for largest single share of global water use • As much as 80% of water withdrawn for irrigation never reaches intended destination – Cheap cost encourages over-use • Waterlogging • Salinization Fertilizer Lack of nitrogen, potassium, and phosphorus often limits plant growth – Adding nutrients via fertilizer usually stimulates growth and increases crop yields • 1950 - Average of 20 kg/ha fertilizer used • 1990 - Average of 91 kg/ha fertilizer used – Manure and nitrogen-fixing bacteria are alternative methods of replenishing soil nutrients Energy Farming in industrialized countries is highly energy-intensive – Between 1920-1980, energy use rose directly with mechanization of agriculture, and indirectly with spraying of chemicals – Altogether, US food system consumes 16% of total energy use • Most foods require more energy to produce, process, and transport than we yield from them • Average food item in US diet travels 2,000 km Pests and pesticides Biological Pests - Organisms that reduce the availability, quality, or value of resources useful to humans – Only about 100 species of organisms cause 90% of crop damage worldwide • Insects are most frequent pests – Make up three-fourths of all species Current pesticide use EPA estimates total pesticide use in the U.S. amounts to about 5.3 billion pounds annually – Roughly 80% of all conventional pesticides applied in the U.S. are used in agriculture or food storage and shipping • Homes and gardens account for only about 8% of total pesticide use in the U.S. • Golf courses use more pesticides per acre than farms Pesticides benefits Disease Control – Many insects serve as disease vectors • Malaria, Yellow Fever Crop Protection – Using pesticides, pre-harvest losses to diseases and pests are at 30%, with post-harvest losses at an additional 20-30% – In general, farmers save an average of $3-$5 for every $1 spent on pesticides Some pesticide types Organophosphates - Extremely toxic to mammals, birds and fish (Malathion) – Outgrowth of nerve-gas research Carbamates - Similar to organophosphates (Sevin) – Extremely toxic to bees Chlorinated Hydrocarbons - Fast acting and highly toxic to sensitive organisms (DDT - mothballs) – Persistent - Tend to biomagnify Environmental persistence and mobility Because chlorinated hydrocarbons are so persistent, they tend to show up far from the point of dispersal – Stored in fat bodies, and thus tend to bioaccumulate • High levels detected in upper levels of food chain – DDT banned from US for over twenty years, but high levels still detected in some areas Environmental persistence and mobility Many persistent organic pollutants were banned globally in 2001 – Use was banned or restricted in developing countries for years, but between 1994 and 1996, the U.S. shipped more than 100,000 tons of DDT and POP’s annually • Many returned to U.S. in agricultural products and migrating wildlife Biomagnification Cells have special mechanisms for bioaccumulation - selective absorption and storage – Dilute toxins in the environment can build to higher levels inside cells and tissues Biomagnification - toxic contents of a large number of organisms at a lower trophic level is accumulated and concentrated by a predator at a higher trophic level Pesticide problems Non-Target Species – Up to 90% of pesticides never reach intended target – Bees • Millions lost to beekeepers • 10x that lost to crops Pest problems Pesticide Resistance – Resistant members of a population survive pesticide treatment and produce more resistant offspring Evolution of pest resistance Pest resistance Pesticide problems Broadcast spraying is also likely to kill beneficial predators – Under normal conditions many herbivorous pests are controlled by natural predators With advent of chemical pest controls, farmers have tended to abandon traditional methods of pest/pathogen control – Mixed crops and rotation regimes Pesticide problems Endocrine disrupters Pesticide problems 25 million people suffer from pesticide poisoning 20,000 die each year from improper use of pesticides Regulating pesticide exposure Less than 10% of active pesticide ingredients have been subjected to a full battery of chronic health-effect tests – Of the 321 pesticides screened, EPA reports 146 are probable human carcinogens • Since 1972, only 40 pesticides have been banned New crops Most of world food comes from 16 widely grown crops – At least 3,000 species of plants have been used for food at some point in time • Many new or unconventional varieties might be valuable food supplies – Winged-bean – Tricale Green revolution Most major improvements in farm production have come from technological advances and modification of a few well-known species – Corn yields jumped from 25 bushels per acre to 130 per acre in last century • Most of gain accomplished through conventional plant breeding Genetic engineering Genetically Modified Organisms (GMO’s) – Contain DNA possessing genes borrowed from unrelated species • Can produce crops with pest-resistance and wider tolerance levels • Opponents fear traits could spread to wild varieties, and increased expense would largely hurt smaller farmers – Estimated that 60% of all processed foods in North America contain transgenic products Round-up Ready Soybeans Pest resistance and weed control Biotechnologists have recently created plants containing genes for endogenous insecticides – Concern has arisen over several points • Spread of genes into wild populations leading to resistance in pests • Effect on nontarget species Bt corn and monarch butterflies Bt corn contains gene from Bacillus thuringiensis Protects against European Corn Borer Pollen from Bt corn kills monarch larvae Is genetic engineering safe ? Environmental and consumer groups have campaigned against transgenic organisms – “Frankenfoods” – Starlink controversy U.S. Food and Drug Administration declined to require labeling of foods containing GMO’s – New varieties are “substantially equivalent” to related traditionally-bred varieties Sustainable agriculture Soil Conservation – Managing Topography • Contour Plowing - Plowing across slope to slow flow of water • Strip Farming - Planting different crops in alternating strips along land contours • Terracing - Shaping land to create level shelves of earth to hold water and soil • Plant perennial species Sustainable agriculture Soil conservation Providing Ground Cover – Annual row crops cause highest rates of erosion because they leave soil bare for much of the year • Leave crop residue after harvest • Plant cover crops after harvest (such as rye, alfalfa and clover) Low-input sustainable agriculture Do not depend on chemical fertilizers and pesticides, and use antibiotics only to combat illness – Typically do not produce as high quality product as intensive farmers, but production costs are lower, and often obtain higher prices Shade-grown coffee and cocoa Alternatives to pesticide use Behavioral Changes – Crop Rotation – Flooding Fields – Habitat Diversification – Adjusting Planting Times – Plant Mixed Polycultures Biological controls Biological controls Biological control - bacteria Bacillus thuringiensis Biological control – parasitic wasps Biological control - ladybugs Alternatives to pesticides Natural insecticides Still can be very toxic More likely to break down quickly Neem is an example Integrated Pest Management Flexible, ecologically-based strategy that uses a combination of techniques applied at specific times aimed at specific pests – Tries to minimize use of chemical controls and avoids broad spectrum controls – Employs economic thresholds to determine the point at which potential economic damage justifies pest control expenditures Is organic the answer ? Numerous studies have shown organic, sustainable agriculture is more ecofriendly and leaves soil healthier than intensive, chemical-based mono-culture cropping – Currently, less than 1% of all American farmland is devoted to organic growing, but market for such crops is growing Organic farming Average yields are 20% lower than conventional farming Costs lower Prices paid are higher Net returns higher with organic crops 56% less energy used
