Unit 5 Test Part 2 Midterm Review Flashcards
Slash and Burn Farming
Slashing and burning forest or other land in order to clear it for agriculture and return nutrients to soil
Typically not done at industrial scale, but lots of small scale burn operations happen in S. America
Causes runoff and carbon emissions (carbon sequestration undone) and air pollution more than other types of agriculture and land clearing
Fertilizer
Mostly synthetic, especially post green revolution (manure was common pre green revolution)
More efficient, but associated with fossil fuel use due to manufacturing requirements
Stifles ‘brown food webs’ due to lack of decomposers and other organisms
May lead to long term nutrient imbalances, as only desirable nutrients are added, degrading the soil over time
Leads to Eutrophication
Can contaminate groundwater with nutrients
Fertilizer Post WWI
Government realized that nitrate from WWII weapons ammunition stock would make a good fertilizer and thus began the era of synthetic fertilizer
Synthetic fertilizer is widely used with many negative environmental consequences
Health effects? Cancer concerns, Blue Baby Syndrome, Etc.
Spray Irrigation
This is what it sounds like- essentially a giant sprinkler
Water is shot into the air and then falls down
This is good for plants because it mimics rainwater
This always requires pipes, valves, machinery, and usually greenhouses gasses in some way or form
Significant water loss due to evaporation
Drip Irrigation
Water slowly applied to plant root zone
Much more efficient than spray irrigation- less water loss, less runoff, and less leaching
Areas between plant rows remain dry, which could inhibit weed growth in some areas
more expensive
Flood Irrigation
Entire fields are flooded- can be less labor intensive and great for certain crops
Uses a lot of water, and a lot of it seeps into the ground, often bringing fertilizer with it
Land must be level, and soils must be loamy to stay saturated
Furrow Irrigation
Similar to flood irrigation, but channels between crops are flooded with water
Different systems can do this differently, but most will channel water within the furrows. Some may have pipes connecting furrows to root zone of crops
Only works for row crops- probably more efficient use of water than flood irrigation
Concentrates water in the soil- could concentrate macronutrients or salts
Waterlogging
Occurs when too much water is left to sit in the soil, which raises the water table of groundwater and inhibits plants ability to absorb oxygen through their roots
In many places, we are worried about a declining water table- but water logging fields, especially flooding them, can raise the water table
Allows nutrient pollution more easily into groundwater
Oversaturated the soil for plants and depletes oxygen potential
Salinization
occurs when the salts in groundwater remain in the soil after the water evaporates. Over time, salinization can make soil toxic to plants
Water used in agriculture naturally or artificially accumulates salts from the environment - especially when water runs off - and even more so in areas where salt is applied in copious amounts in winter
Salt accumulates in soils (through runoff going into water, water used for irrigation) - especially when furrows concentrate it into channels
When water evaporates, salt is left in soil
Salty soil is BAD for crops - salt toxicity is a huge problem for plants (and animals!) that are not evolved to deal with excessive amounts of it, limits bacteria, decomposed things can’t exist in salty soil
Aquifers
can be severely depleted if overused for agricultural irrigation, as has happened to the Ogallala Aquifer in the central United States
9% depletion thus far with 6,000 year recharge time under expected rain conditions
Is this renewable?? No
27% of US irrigated land falls within this aquifer
Aquifer also provides drinking water to nearly 2 million people
Keystone XL Pipeline
Proposed (now scrapped) pipeline would have crossed aquifer
Oil spill or leak from pipeline could have potentially contaminated portion of the aquifer, threatening water supply for drinking and crops
Many pipelines cross through aquifers, including the OGallala and have done so without significant known incidents - but groundwater contamination is a serious concern for much of the country and world
Groundwater pollution is incredibly difficult to remediate and pollutants can be a very costly or long lasting issue
GMOs
A raging debate - GMOs help increase agricultural efficiency, but have bioethical and perhaps health concerns
If you genetically engineer a plant to be herbicide resistant, and spray a field with herbicide, you can target everything more easily
Pesticidies: DDT
Insecticide
Major implications in malaria prevention
Livestock and crop production
Major effects on raptors (ospray, bald eagles, etc.), largely due to biomagnification
Couldn’t make protein to strengthen egg shells, crushed them when they tried to incubate them
Banned in United States after a series of usage restriction in 1950s and 1960s
Silent Spring by Rachel Carson
Silent Spring
Book by Rachel Carson
Warned against dangers of pesticides like DDT, made a big impact on public opinion of pesticides
Regulation of Pesticides
Federal Insecticide, Fungicide, and Rodenticide Act- FIFRA
“a pesticide is any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest, or intended for use as a plant regulator, defoliant, or desiccant, or desiccant, or any nitrogen stabilizer”
Pesticides must be registered (licensed) with the EPA. Before EPA may register a pesticide under FIFRA, the applicant must show, among other things that using the pesticide according to specifications “will not generally cause unreasonable adverse effects on the environment.” Taking into account the economic, social, and environmental costs and benefits of the use of any pesticide, FIFRA defines the term “unreasonable adverse effects on the environment” to mean the following:
Any unreasonable risk to man or the environment, taking into account the economic, social, and environmental costs and benefits of the use of any pesticide.
Any human dietary risk from residues that result from use of a pesticide in or on any food inconsistent with the standard under section 408 of the Federal Food, Drug, and Cosmetic Act
