Agriculture and Pesticides

Agriculture and Pesticides Unit 7

What do humans need to survive? • Three major biological molecules: • Carbohydrates (sugar, starch) • Lipids (fats, oils) • Proteins • All three molecules are necessary for cellular respiration and making up the human body • Also need vitamins and minerals (inorganic elements)

What if we don’t get what we need? • U.N. Food and Agricultural Organization (FAO) estimated that 828 million people lack access to the food needed to be healthy and productive  most in developing nations

What if we don’t get what we need? • Average adult needs 2,600 kcal per day • Undernourished = consume less calories than needed • Malnourished = consume enough calories, but not enough of a specific vitamin, mineral, molecule, etc. • Both conditions can lead to poor physical and mental development

What if we don’t get what we need? • Marasmus = emaciation caused by a diet low in both calories and protein, very common in young children, slow growth, atrophy, can be reversed with proper diet • Kwashiorkor = protein deficiency, edema, dry/brittle hair, stunted growth, mental retardation, swollen abdomen, can be treated with proper diet

Too much of a good thing… • Overnourished = too many calories and nutrients, can result in obesity, diabetes, heart failure, etc.

Food distribution • Human population continues to grow  producing enough food continues to be a problem • Food production can be increased for the short term, but can it be maintained for the long term? • Famine = widespread shortage of food, can be caused by fire, flood, war, etc.

Maintaining Grain Stockpiles • World grain carryover stocks = amounts of rice, wheat, corn, and other grains remaining from previous harvests • World food security = goal in which all people have access at all times to adequate amounts of food • World stockpiles are currently falling

Poverty and Food • Currently, enough food is produced so that everyone could have an adequate (not generous) diet • People are still starving to death  food is not evenly distributed • Poverty means that many people cannot afford food

Economic and Cultural Effects on Human Nutrition • It costs a lot of money to produce, store, transport, and distribute food • Areas with the greatest need often have the least resources • Dishonest or ineffective governments can also prohibit food from reaching the people who need it

Economic and Cultural Effects on Human Nutrition • Cultural acceptance can play a large role in whether people eat certain foods • Different foods may not be accepted  some people eat insects, dog meat, etc. • Food may not be eaten due to religious reasons • Overall, there has been a trend toward greater uniformity in the food we eat

Plants and Animals that Stand Between People and Starvation • 100 species provide 90% of the food that humans consume either directly or indirectly • 15 plant species provide bulk of food for humans • Sugarcane • Corn (maize) • Rice, paddy • Wheat • White potato • Cassava (manioc) • Soybean • Barley • Sweet potato • Sorghum • Peanuts (ground nuts) • Oats • Rye • Beans, dry • Peas, dry

Types of Agriculture • Industrialized agriculture (high-input agriculture) = common in developed countries, large inputs of capital and energy to run machinery, irrigate crops, make fertilizers, etc. result in high yields (amount of a food crop produced per unit of land) • This reduces the amount of farm land needed, but can degrade the soil, increase pest resistance, etc.

Types of Agriculture • Subsistence agriculture = production of enough food to feed oneself and one’s family, with little left over to sell or reserve for hard times • Requires large input of energy, but it comes from humans and farm animals

Types of Agriculture • Shifting cultivation = form of subsistence agriculture; short periods of cultivation are followed by longer periods of the land lying fallow (uncultivated) in which the land reverts to forest • Supports relatively small populations; requires a lot of land per person

Types of Agriculture • Slash-and-burn = form of subsistence agriculture; involves clearing small patches of rainforest to plant crops • Tropical rainforest soils do not have many nutrients, so farmers must move their plot every 3 years or so

Types of Agriculture • Nomadic herding = form of subsistence agriculture; livestock is supported by land that is too arid for successful crop growth • Herders must constantly move their livestock to find adequate food

Types of Agriculture • Intercropping = intensive form of subsistence agriculture; involves growing a variety of plants simultaneously on the same field • Monocultures = certain crops that produce higher yields when grown together • Different pests are found on each crop, preventing the build-up of any one pest • Native Americans practiced intercropping  corn, beans, and squash  roots all at different depths, beans perform nitrogen fixation • Polyculture = complex form of intercropping; plants that mature at different times are planted together and harvested throughout the year

Effect of Domestication on Genetic Diversity • Recall: Greater genetic diversity contributes to a species’ long term survival by providing the variation that enables each population to adapt to changing environmental conditions • Domesticated = adapted to humans; a plant or animal that has been so altered from their original ancestors that it is doubtful they could survive and compete successfully in the wild; greatly reduced genetic diversity

Effect of Domestication on Genetic Diversity • Today, we have very little genetic diversity in our livestock and crops • These species do not need to survive in the wild  they are watered, fed, fertilized, protected from pests and predators, immunized against disease, etc. • However, when a disease does break out in a domesticated population, it evolves rapidly and spreads rapidly, causing greater losses than those that would occur in a natural, varied population

Global Decline in Domesticated Plant and Animal Varieties • There is a global trend to replace local varieties and breeds with just a few kinds • Local breeds are becoming scarce or even extinct • To preserve older, more diverse varieties of plants, many countries are collecting germplasm any plant or animal material that may be used in breeding, including seeds, plants, plant tissues, sperm, eggs, etc.

Who owns crop diversity? • Companies develop species from germplasm, and then sell them to farmers • Plant breeders want free access to germplasm, agricultural firms want to patent it and sell it • International Treaty on Plant Genetic Resources for Food and Agriculture = FAO adopted it in 2001, limits the genetic materials that agricultural companies are able to patent and allows farmers to save, use, exchange, and sell farm-saved seeds. Germplasm is available to plant breeders for a royalty fee. The United States has not signed or ratified the treaty.

Increasing Crop Yields • Farmers have been using selective breeding to increase crop yields for tens of thousands of years • Irrigation and fertilization are also ancient practices • Recent practices include pesticides and genetic engineering

The Green Revolution • The production of more food per acre of cropland by using modern cultivation methods and new, high-yielding varieties of certain staple crops • Inorganic fertilizers, mechanized machinery, pesticides, etc.

Problems with the Green Revolution • Developing countries are dependent on imported technologies at the expense of traditional agriculture • High energy costs  fossil fuels • Disruption to water cycle via irrigation, building canals, dams, etc. • Benefits large landowners, but not subsistence farmers • Disrupts local ecology on a larger scale

Increasing Crop Yields in the Post-Green Revolution Era • World demand for rice, wheat, and corn will increase by 40% by 2020 due to increase in population and number of people who can afford meat • Best arable land is already cultivated  increasing amount of farmland won’t work • Freshwater shortage, increased cost of agricultural chemicals, deteriorating soil quality, etc. • What can we do?

Increasing Crop Yields in the Post-Green Revolution Era • Scientific efforts to improve crops  genetic engineering • More efficient irrigation • Soil conservation

Increasing Livestock Yields • Hormones = chemical messengers produced by a living organism; helps regulate growth, reproduction, and other important biological functions • Hormones are usually given to livestock via ear implants

Increasing Livestock Yields • European Union currently bans all imports of hormone-treated beef because of health concerns for human consumers • Could cause cancer or affect growth of young children • Hormones are in meat, but also present in cattle waste, which makes its way to our drinking water

Increasing Livestock Yields • Antibiotics = chemicals used to kill bacteria and prevent disease • Antibiotics are found in low doses in most livestock • An animal that has been given antibiotics tends to have 4-5% more weight than other animals, probably because they aren’t using as much energy to fight infections • Problem: Using antibiotics in livestock makes them less effective in humans  bacteria are evolving to resist them

Food Safety • In the United States, there are about 76 million cases each year of food-borne illnesses • 325,000 require hospitalization; 5,000 result in death • USDA addresses safety of meat, poultry, and products that contain meat or poultry • U.S. Food and Drug Administration (USFDA) is responsible for all other foods, such as fresh produce, milk, seafood, canned foods, and processed foods that do not contain meat

Food Safety • Health experts say that the greatest risks come from bacteria, viruses, parasites, etc. • Food additives, pesticide residue, allergenic substances, etc. are of concern, but not nearly as important • Do you agree?

Food Safety • There has been a 23% decline in food borne illnesses since 1996 • This is probably due to increased surveillance and improved technology • It is now easier to trace and stop an outbreak

Food Processing and Food Additives • Two major aspects of food processing: • Drying, freezing, canning, pasteurizing, curing, irradiating, etc. • Food additives = chemicals that enhance the taste, color, texture, nutrition, etc. of food

Food Processing and Food Additives • Sugar and salt = two most common food additives • Can be used to make food taste better or to preserve it (fruit jelly, salted meat)

Food Processing and Food Additives • Coloring agents = used to make food visually appealing  natural or synthetic • Preservatives = chemicals added to food to retard the growth of bacteria or fungi that would cause the food to spoil  sodium propionate, potassium sorbate, etc. • Antioxidants = chemicals that prevent oxidation  butylatedhydroxyanisole (BHA) and butylatedhydroxytoluene (BHT)

Food Processing and Food Additives • Nitrates (compounds with NO3-) and nitrites (compounds with NO2-) are used as food additives for curing meats • Can react with other chemicals in food or tobacco to form N-nitroso compounds in the stomach  can cause cancer

Protection of the Consumer • USFDA is charged with the responsibility of monitoring food additives • 1958 – Any new food additive must undergo extensive toxicity testing before it is declared “safe” • Additives used prior to 1958 do not have to undergo such testing • Some have been tested and deemed safe, some have been banned  not all have been thoroughly tested

Are Food Additives Bad? • Cancer, health problems, etc. vs. cheap, easy to access and preserve food • Concern that chemicals will act synergistically, or that the total effect will be greater than the sum of their individual effects • Natural vs. synthetic additives

The Environmental Impacts of Agriculture • Agriculture can impact the ability of nonagricultural terrestrial and aquatic ecosystems to provide ecosystem services clean air, clean water, fertile soil, etc. • Produces pollution  air pollution, water pollution, nitrates from animal waste, etc.

The Environmental Impacts of Agriculture • Shift in methods  small family farms to large corporate farms • Livestock is crammed into small pens in large buildings  high concentration results in lots of waste and high risk of disease • Pesticides result in insects and weeds that are resistant, also kill aquatic life

The Environmental Impacts of Agriculture • Degradation = natural or human-induced process that decreases the future ability of the land to produce crops or support livestock

The Environmental Impacts of Agriculture • How much water do we need to grow crops? • 1,000 tons of water = 1 ton of grain • 70% of freshwater use

The Environmental Impacts of Agriculture • Habitat fragmentation = dividing a habitat into small, fragmented pieces • Clearing grasslands and forests, draining wetlands • 90% of North American tallgrass prairie = converted to agriculture

Using more land for cultivation • We use about the same amount of land for agriculture as we did 50 years ago • Almost all of the most fertile land is already being farmed, though some is lost to urbanization • The amount of dry land being irrigated has increased  70% of the world’s total irrigated land is in Asia, and the number continues to grow

Moving towards sustainable agriculture • Sustainable agriculture, aka alternative or low-input agriculture, relies on beneficial biological processes and environmentally friendly chemicals that disintegrate quickly and do not persist as residues in the environment.

Moving towards sustainable agriculture • Combining modern agricultural techniques with traditional farming methods • Planting a variety of crops to protect the farmer against unexpected changes in the marketplace and disease • Breeding disease-resistant crops and maintaining animal health instead of relying on antibiotics

Moving towards sustainable agriculture • Conserving water and energy • Using natural predator-prey relationships instead of chemical pesticides  birds, other bugs, etc. • Growing crops in ideal areas  In Oregon, apples don’t have major pest problems but peaches do. In Colorado, the opposite is true.

Moving towards sustainable agriculture • Soil preservation through crop rotation, conservation tillage, contour plowing, etc. • Adding animal manure to soil to reduce need for synthetic fertilizer • Using soybeans for nitrogen fixation between crops

Moving towards sustainable agriculture • Organic agriculture = no pesticide chmicals • Integrated pest management (IPM) = limited use of pesticides, but incorporated with crop rotation, disease-resistant crops, biological pest controls, etc.

Agriculture and Pesticides