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a person whose diet doesn't contain the 2,200 kcal per day considered necessary for a healthy productive life
1. grain to be used as seed is eaten
2. breeding animals are slaughtered for food
3. individuals too weak or sick to work on growing more food
1. drought, earthquake, severe storms, politics, & economics
2. bad weather and insect infestations can cause crop failure, but normally they are not prolonged
a nutritional imbalance caused by a lack of specific dietary components or an inability to absorb or utilize essential nutrients
-can lead to: stunted growth, developmental abnormalities, reduced mental capacity or death
-used in the syntehsis of an endocrine hormone that regulates metabolism and brain development.
-can cause goiter and reduced mental ability
starchy foods that make up the bulk of the world's diet (wheat, rice, and manioc (cassava))
-lack essential vitamins
-wider array of nutrients needed
-meat provides these in developed countries
body mass greater than 30 pounds above the normal average person.
-62% of adult Americans are overweight, up from 40% a decade ago
-1/3 are obese
americans advised to eat daily servings of meat, dairy, grains, fruit and veggies.
-revised in '92 to reduce intake of meat,, dairy, fats, and sweets
-unsaturated plant oils should make up 30-40% of dietary calories
-trans fat is not recommended at all
very few species used to feed the human population. 12 seeds & grains
3 root crops
2 domestic fowl
a few fish and couple of other marine life forms
-Northern Europe and Northern Asia: potatoes, barley, oats, rye
-Amazonia, Africa, South Pacific: cassava, sweet potato
A. meat consumption has risen from 10kg per person/yr in 1960 to 26kg currently and estimated 40kg in 2030
-increase demands could be met by S.American production & genetic engineering of livestock
-acres devoted to soy in Brazil has increased 20x in past 40 yrs & yield/acre has doubled
-clearing forested land for agricultural uses
B. N. American (US) livestock approach
-concentrated animal feeding operations (CAFO)
-more than 1/3 of the world's maize, soy, and coarse grain fed to livestock yearly
-in the US livestock produce 25x the waste as humans
-US livestock consumes 8x (25 million lbs) as much antibiotics as humans
-US livestock production is very much an industrialized process
a. currently harvested 85 million metric ton of wild seafood per yr
b. we utilize 2/3 directly, remaining 1/3 feed captive raised aquatic species: aquaculture
-aquaculture accounts for 1/2 the seafood we eat
c. main animal protein for 1.5 billion
d. since 1989, 13 of 17 of marine fisheries have declined below commercially sustainable levels
e. estimated that the oceans will be exhausted by 2048
1. farmers are paid subsidies to not farm highly erodible land, thus conserving soil and not polluting waterways
2. subsidies for some row crops are much greater than CRP subsidies
3. CRP provides milions of acres of wildlife habitat through the Midwest.
4. hundreds of thousands of acres did not get relisted in CRP this past year due to the high commodity value of corn b/c of the increase production of ethanol from corn
a. living mixture of decaying organic matter, weathered minerals (rocks), and living organisms
-soil can be lost to wind and rain as well as having the nutrients drained
-can suffer extremely long-term damage from a very intense fire. if fire hot enough, can "bake" the soil and kill all living organisms contained w/in. moderate temp fires can be good for the soil by helping to breakdown large pieces of organic matter.
-topsoil can accumulate by up to 1mm per year under best circumstances. it can very easily be lost at a much higher rate however.
*no-till agriculture is one example in which soil
(especially topsoil) can be conserved
-sand (2mm-.05mm): allows water to drain from soil, thus not swamping plants. also more prone to dry out quick w/o rain. least effective in holding minerals
-silt (.05mm-.02mm): very fine/powdery feeling btwn fingers. ability to hold water/ions btwn sand & clay
-clay (<.02mm): extreme fine powder. normally feels as if its one unit b/c it sticks together so tightly. can be impermeable to water & hold mineral ions so tight that plants can't uptake them for utilization
-40-40-20: composition of sand, silt, and clay is termed loam
-humus: partially decomposed organic matter. very effective at holding nutrients and water, both of which are readily available to growing plants.
*farmers normally till under the residue of crops in the
fall so that decomposers (earthworms) can begin
adding it back to the humus layer
soil contains billions of individual organisms every hectare.
a. just as we found numerous microscopic organisms in our water samples, the same would be fond in soil
b. algae, bacteria, fungi, and numerous invertebrates
*all responsible for constant recycling of topsoil
Rhizobium bacteria and the roots of legume plants. plant provides bacteria w/ the products of photosynthesis and the bacteria provides the plant w/ added surface area for absorption. in association the bacteria is able to fix nitrogen for the plants use. bacteria is unable to fix nitrogen w/o the association w/ legume root.
*legumes are used in rotation w/ other crops to replenish the soil nitrogen. less fertilizers used b/c of rotation
1. unique compositon of multiple"soil horizon": distinct layer of soil characterized by it's color and texture.
2. normally the top 2 soil horizons are the litter layer or horizon O (decomposing organic matter) and topsoil/horizon A
*almost all living organisms and organic matter in the soil are located in these 2 horizons
3. E Horizon: often present below A horizon. layer lacks soluble nutrients as rainwater has washed them downward
4. B Horizon (subsoil): accumulation of nutrients washed from the E horizon. can form a "hardpan" layer which holds water close to the surface for plants.
5. C Horizon: partially broken rock fragments of the parent material. most of the parent material in the US was deposited by glaciers
-aprox 12.5% of earth's land mass currently used for agriculture. believed that 4x that amount could be used, but b/c of lower quality, serves as a biological resource or would be a high erosion area
-less US land is currently in agri production than 100 yrs ago and less than 600 years ago in Europe.
*increased production per acre is mainly due to improved crop varieties, fertilization, irrigation, and improved pesticides
*largest increase in agri acres in production during past 30 years = from south America and oceania
loss of agricultural land per year
7.4 mil acres ruined by erosion
9.9 mil acres turned to desert
19.7 mil acres converted to non-agri uses; roads, homes, industry, Northville
during past 50 yrs, 4.7 BIL acres of agri land have been degraded to some extent
22 mil acres of former ag land so degraded that they will no longer support ag production. could be from: erosion, nutrient depletion, salinization, compaction. 25 bil metric tons of topsoil lost to erosion/yr = 1% of ag land in production. disrupts streams, rivers, wetlands, coral reefs.
advancement of desert due to land use practices in areas bordering deserts. arid regions which are used to intensively and result in a loss of cover plant.
ex: China and the green wall to stop the Gobi desert
*ag. is the largest user of water. 2/3 of all fresh water withdrawn from lake river, and groundwater is for irrigation.
*the bulk of world irrigates w/ open ditches = 80% water lost before reaches the plant
*excessive irrigation result in WATERLOGGING =soil is saturated w/ water to the point that plant roots die from a lack of oxygen
*SALINIZATION: mineral salts accumulate in the soil to a lethal level for the plants. more come where saline water is used for irrigation
*nitrogen & phosphate runoff from ag fields and animal feedlots are a major source of aquatic pollution. in some areas, nitrate level sin drinking water are unhealthy, espec for kids
*major reasons for increase in ag production during past few decades.
-N, P, and K are major fertilizers
-more fertilizer doesn't mean more yields, there is a limit and it can become dangerous to plants
*manure and green manure: crops grow to add nutrients to soil and then tilled under
*interplanting w/ crops capable of fixing nitrogen, manly legumes
1. energy used for tractors, fertilizers, pesticides, and transport of the products.
a. avg distance that food travels to reach consumer in US = close to 1,500 miles
b. distribution can cause as much as 5x the energy needed to produce crop
c. farming/distribution consume 16% of total energy use in US
d. local grown produce? how could this reduce total energy demands of US
have limitations due to drought, pests, moisture lvels, infertile soil, and length of growing season.
1. other less well known species may hold the key to increased production. by selecting genes from other species which improve their performance overall harvest yields could (and have) increased.
a. GENETICALLY MODIFIED ORGANISMS (GMO's). some plants being developed that actually grown vaccine in crop.
b. early 1900's, US corn averged about 25 bushels/acre. today, 130 bushels/acre
traditional crops cont.
c. GREEN REVOLUTION: increased yields from new varieties of plants
d. problem w/ green revolution - they only perform under optimal conditions. otherwise the production is less than traditional varieties. poor farmers and poor countries unable to reap the benefits from these new altered varieties.
e. estimated that GMO's are in 60% of all processed food sold in the US
1. Bacillus thuringiensis (Bt): a bacterium that makes toxins lethal to Lepidoptera and Coleoptera
a. genes for those toxins have been spliced into corn, cotton, potato and even gold course grasses
b. farmers have been able to reduce their pesticide spraying by 80-100% w use of Bt modified plants
c. risk of creating pests resistant to Bt if other methods not used
*occasional spraying or mixed Bt infused seed w/ regular seed
a. company that produces round-up (Monsanto) has developed seed which is resistant tot round-up,, a glyphosate that kills almost all plants.
b. allows farmers to control weeds even after crop is growing w/o tilling and thus reducing erosion
plowing w/ the slope or contour of the farm field
attempting to minimize the number of times a farmer disturbs the soil
1. conserve-till and no-till are similar methods in which no soil is disturbed or only a small amount in order to plant the seed. helps to slow erosion
2. problems w/ reduced tillage is that often times more chemicals are needed to control for weeds and insects
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