Presentation on theme: "Where does our food come from?"— Presentation transcript:
1Where does our food come from? Croplands (mostly grain) – provide 77% of the world’s foodRangelands (meat) supply 16%Oceanic fisheries (fish and shellfish) – 7%
2How Is Food Produced? Sources of food Primary plants: Wheat, corn, and ricePrimary animals: fish, beef, pork, and chicken14 plant and 8 animal species provide 90% of the global food calories
3Major Types of Agriculture Industrialized agricultureLarge amounts of fossil fuel, water, fertilizer, and pesticides to produce monoculture crops or livestock animalsPlantationForm of industrialized agriculture – single ownershipTraditional subsistence agricultureProduce only enough for the familyTraditional intensive agricultureIncrease outputs for profit
4Industrialized Agricultural Wastes and Land Pollution Animal ConfinementWaste runoffOvergrazingIncreases soil erosionSedimentationNutrient applicationIrrigationPesticides
5Waste runoff increases nutrients and pathogens in streams
6Overgrazing typically strips the land of any natural protection and leaves the soil very susceptible to erosion
7Runoff carries sediments, nutrients and pesticides into streams that damagesfish habitat
8Agriculture alters native habitats and reduces native biodiversity
9Major Types of Agriculture Plantation - Form of agriculture that involves concentrated ownership of land with the means of production in the hands of one family or corporation, the use of hired labor, and mono-crop production for sale.Cash crops mostly for sale in developed countriesBananas, coffee, soybeans
12Producing Food by Green-Revolution Techniques Since 1950, increase in global food production has come from increased yields per unit area of crop land.
13Producing Food by Green-Revolution Techniques Green revolution involves three steps:High-input monoculture using selectively bred or genetically-engineered cropsHigh yields using high inputs of fertilizer, extensive use of pesticides and high inputs of waterMultiple cropping – increase the number of crops grown per year on a plot of land.
14Green Revolutions First green revolution (developed countries) Second green revolution(developing countries)Major International agriculturalresearch centers and seed banks
15Producing Food by Traditional Techniques Interplanting – simultaneously grow several crops on the same ground. Reduces chance oflosing year’s crop to pests, bad weather, etc.
16Producing Food by Traditional Techniques Types of InterplantingPolyvarietal cultivation – planting several varieties of the same cropIntercropping – grow two or more different crops at the same time (grain+nitrogen fixing plant)Agroforestry (alley cropping) – crops and trees are grown togetherPolyculture – many different types of plants that mature at different times are grown together
17Causes of Soil Erosion Wind Water People – farming, logging, construction (or any activities that weaken root strength)
32Second Generation Pesticides Primarily synthetic organic compoundsBroad-spectrum agents – toxic to many speciesNarrow-spectrum agents – toxic to few speciesPersistence in the environment
33The Case for Pesticides Save human lives – spread of diseaseIncrease food supplies and lower costsWork better and faster than alternativesHealth risks may be insignificant compared to benefitsNewer pesticides are becoming saferNew pesticides are used at lower rates
34Characteristics of an Ideal Pesticide Affects only target pestsHarms no other speciesNo genetic resistanceBreaks down quickly in the environmentBe more cost-effective than doing nothing
35The Case Against Pesticides Genetic resistanceThe pesticide treadmill – pay more for less effectCan kill non-target and natural control speciesCan cause an increase in other pest speciesPesticides do not stay putCan harm wildlifePotential human health threats
36Bioaccumulation and Biomagnification Persistent (non-biodegradable) toxins build up in an animal over time = bioaccumulationBecome more concentrated at higher trophic levels = biomagnification
37Integrated Pest Management Ecological system approachReduce pest populations to economic thresholdField monitoring of pest populationsUse of biological agents – natural predators, parasites, diseaseChemical pesticides are last resort
38Why is Integrated Pest Management not More Widely Used? Requires expert knowledgeSlower than conventional pesticidesInitial costs may be highHindered by pesticide industry
39Solutions: Sustainable Agriculture Low-input agricultureOrganic farmingProfitableIncreasing funding for research in sustainable techniques