221 terms

APES Unit 8

Industrialized agriculture (High-input agriculture or Modern Intensive Farming)
uses large amounts of fossil fuels, water, inorganic fertilizers, and pesticides to produce large quantities of monoculture crops or feedlot stock.
Traditional Subsistence Agriculture
uses mostly human labor and draft animals to produce only enough crops or livestock for a family. This uses organic fertilizer (manure) which negates the need for extensive irrigation, and natural pesticides.
Traditional Intensive agriculture
Increased use of human labor, draft animals, fertilizer, and irrigation to get a higher yield per area cultivated to produce enough food for the family as well as to sell as a cash crop.
started in the US in the 1950's (1st) and then in India and Indonesia in 1967 (2nd)
Advantages of GR
produce greater number of crops using a high-yield hybrid monoculture crop (wheat & corn for the 1st, and rice for the 2nd green revolution)
Disadvantages of GR
uses large amounts of fossil fuels, inorganic fertilizers, water for irrigation, and pesticides
Interplanting Stategies
Polyvarietal cultivation, intercropping, agroforestry(alley cropping), polyculture.
Polyvarietal cultivation
several varieties of the same crop are planted
2 or more crops are grown at the same time on the same plot (wheat that uses nitrogen and a legume that puts the nitrogen back into the soil. (This is NOT the same as strip cropping!)
Agroforestry (alley cropping)
where crops and trees are alternately planted together
a more complex form of intercropping in which many different plants maturing at various times are planted together. This is by far the best of the strategies - using less fertilizer & water (root systems capture water & nutrients more efficiently), covering the soil year round so there is less soil erosion, multiple habitats are created for natural predators so fewer pesticides are used, fewer herbicides due to the competitive nature of multiple crop plants, and less damage by weather due to a variety of crops.
consumption of 100-400 less calories than the average daily requirement.
Health effects
mental retardation, stunted growth, greater susceptibility of infectious diseases
the average daily requiremnt of 2000 calories are met but they are mostly carbohydrates and few proteins.
a disease characterized by both low # of calories and low proteins. The health effects can be reversed if caught early enough.
Severe protein deficiency brought on by the arrival of a new baby. The calories are made up in carbohydrates. If caught early enough the health effects can be reversed.
Micronutrient deficiencies
Vitamin A - leads to blindness, Iron - causes fatigue, increased risk of infections, dying in childbirth, Iodine - causes stunted growth, mental retardation, and goiters
when food energy exceeds the energy use and causes obesity.
Health problems of Overnutrition
lower life expectancy, greater susceptibility to disease, lower productivity & quality of life
altering the genes of a plant or animal by inserting an alien gene to produce a new desired trait. This is done through traditional methods of cross-breeding or the newer method of genetic splicing, specifically transgenic genetic engineering.
Steps in genetically modifying a plant
1.Identify and extract the gene with the desired trait 2.Then remove the portion of DNA that has desired trait 3.Remove the plasmid from the DNA of E. coli and insert your desired DNA into it 4.Return the plasmid to E. coli and then grow in tissue cultures to make copies 5.Transfer the plasmid to a carrier (like agrobacteirum) 6.The carrier inserts the foreigh DNA into the plant cell to yield the transgenic cell 7.Transfer the plasmid to the surface of a 'gene gun' which will then inject the DNA into the plant cell 8.The plant will now grow with the new trait inserted and expressed in the plant (like disease resistance)
Traditional cross-breeding disadvantages
slow process, taking many years to produce a commercially viable species
Genetic Engineering Advantages
Uses less pesticides, fertilizer, water & land, Increased production and lower cost of food, Boost immunity and develop built-in vaccines for livestock & poultry, Remove lactose, so that lactose-intolerant people can eat dairy products, Create drought resistant crops for semi-arid lands, Create salt tolerant crops for areas of salinization, Faster & cheaper to produce, Can create crops that are tastier, more nutritious and keep longer, Create crops that can be grown for growing medicines, Increase biodiversity on specific species due to greater # of DNA pieces.
Genetic Engineering Disadvantages
Non labeled products could produce allergic responses with inserted DNA, Contamination of other crops through pollen being blown by the wind, Loss of nutritional value, Deduction of the efficiency of anitbiotics, New viruses can evolve from mass production of genetically modified (GM) crops, Increased pest resistance to GM crops, Overall loss of biodiversity due to fewer organisms being developed for crops - only the few staples are being enhanced, The technology of the GM crops is not shared (Monsanto has a terminator gene that requires farmers to buy the seed every year instead of being able to plant some of the saved seeds), GM crops can affect other animals other than the target animals - i.e.monarch butterfly caterpillars are dying when their milkweed plants have been contaminated with the pollen from Bt corn. No assurance of public liability for farmers of GM crops.
How to increase food production for the future
1.Introduce new foods - i.e. the winged bean (a protein rich legume plant which all parts of the plant are totally edible), insects (containing 3-4 times the protein of beef, fish or eggs). 2.Polycultures of perennial plants, which don't need reseeding every year, don't require tilling the soil, reduce energy use, save water and reduce soil erosion and water pollution from eroded sediment. 3.Increased use of organic farming with crop rotation
Methods for using water more sustainably
Use efficient irrigation - drip irrigation, LEPA sprinklers, Center-pivot low pressure sprinklers, Use drought resistant crops like sorghum and Withdrawing water from an aquifer no faster than it is replenished.
semi-arid land that native grasses have adapted to. If too many cattle are feeding off this area then desertification will take place.
where animals are fattened for slaughter by feeding on grain grown on cropland or meal produced from fish or from other animal by-products.
Problems associated with Feedlots
Concentrates pollution problems (foul odors, animal waste storage, animal waste runoff), Greater consumption of grains or fish stock that could feed people instead of livestock, Requires more fossil fuels, Increases the spread of infectious livestock diseases (mad cow disease, hoof-&-mouth disease, bird flu)
Problems associated with Meat Production
More cropland is devoted to feed livestock where it could be used for crops for people if livestock were fed crop residues instead (wheat straw, rice straw, & corn stalks), More water is used for irrigating those crops and to wash away manure in feedlots, Increased water pollution (fecal coliform contamination and eutrophication) from animal waste storage systems and increased use of fertilizers.
Fish and Shellfish Harvesting methods
trawler fishing, purse-seine fishing, longlining, drift-net fishing, aquaculture(fish farms).
Trawler fishing
dragging a funnel-shaped net (open at the neck) along the bottom. It destroys benthic habitats.
Purse-seine fishing
a large net that closes around tuna fish like a drawstring purse. This traps other aquatic animals (dolphins) as well as the fish
fishing vessels put out long lines (up to 80 miles) that contain thousands of baited hooks. This hooks unwanted aquatic animals (pilot whales, dolphins, sea turtles, albatross) along with the swordfish, tuna, and sharks
Drift-net fishing
huge nets hang 50 feet below the surface of the water and can be 34 miles long. This leads to overfishing of the desired species and traps many dolphins, porpoises and seals. There has been a ban on the use of drift-nets since 1992 by the UN but the compliance is voluntary so is rarely followed.
Aquaculture (fish farms)
where saltwater and fresh water fish and shellfish are raised like livestock in feedlots are.
Creating Sustainable Agriculture requires
Slowing population growth, Reducing poverty so that people can grow or buy enough food for better health, Converting to organic farming and polyculture.
3 Types of Soils
clay, silt, sand.
very small sized and flat, uber fine, has as high a porosity as Sand but has a much lower permeability
midsized, fine, smooth
largest of soil types, irregular shaped, gritty,
Soil Profile
the cross-section of soil showing the different soil horizons (layers).
O horison
contains leaf litter and partially decomposed leaf litter
A horizon
TOPSOIL -contains humus (fully decomposed leaf litter), macroinvertebrates, and nutrients
E horizon
Zone of Leaching - where the minerals from the topsoil are drawn down into the lower layers of soil when they are dissolved by the water
B horizon
SUBSOIL -contains some minerals, no other nutrients
C horizon
PARENT MATERIAL - bedrock that is partially weathered (broken down) by oxidation
R horizon
needed in greater amounts by plants -C, H & O (as H2O), P, K, N, S, Ca, Fe, Mg -protein, carbohydrates, fats
needed in smaller amounts by plants - Co, Mn, Cu, Zn, Si, Mo, B, Al, Cl -vitamins, minerals
Soil Profile types that support growth of plants
grasslands, Deciduous forests, Coniferous Forests(these are acidic)
Soil Profile types that don't support growth of plants
deserts, Tropical rain forests
Ped test
a quick way to determine soil type in the field. It is based on the texture (gritty vs smooth & sticky) as well as the length of the ribbon that can be created. (Forming a long ribbon is a characteristic of clay)
Soil Triangle
used to quantitatively determine the soil type after one has found the % Sand and % Silt in testing. Where the two percentages cross designates a certain type of soil.
the amount of pores spaces between soil particles. This is found by saturating a known volume of soil and then finding the percentage of water to volume of soil.
the rate at which water moves through soil. This is found by timing how long it takes for a known volume of water to go through saturated soil.
Acid Soils
can be neutralized by adding lime.
Basic Soils
(like those of southwestern US) can be neutralized by adding sulfur (which is slowly converted into sulfuric acid by bacteria).
the increase in salt concentration on the surface of the soil due to excess irrigation
Salinization can be reduced by
flexible cropping, deep-rooting crops, salt-tolerant crops, snow management, surface drainage.
Flexible cropping
land is left fallow (not planted) when there would be insufficient soil moisture as in an excessive drought.
Deep-Rooting Crops
will dry out the subsoil so that the salts won't be dissolved. Examples of deep-rooted crops are alfalfa, safflower, wild ryegrass, tall wheatgrass and sweet clover.
Salt-Tolerant Crops
forage crops (Bermuda grass, tall wheatgrass, fescue) are more tolerant of increased salt concentrations. Planting these areas for grazing or for food for grazers will utilize the area better than planting for human consumption crops.
Snow Management
deep snowdrifts cause for more percolation down to subsoil which increases salinity. Standing stubble will prevent drifts or deep-rooted perennials.
Surface Drainage
draining ponds in recharge areas The use of open trenches, buried pipes, grassed waterways and adequate culverts will prevent ponding of water in fields
(where the soil is plowed & disced leaving very little vegetation at the surface) it is effective in weed control, it retains soil moisture, it gives short-term nutrients (from the previous crop) to the soil, and reduces the risk of residue-borne plant diseases. It also leaves the soil vulnerable to water and wind erosion.
Other benefits of summerfallow can be achieved by
stubble mulching, zero tillage, weed control, snow management.
Stubble mulching
leaving the stubble of the previous crop as a soil cover
Zero tillage
Replanting using no-till practices
Weed control
by using stubble, no-till, and/or cover crops
Snow management
decreasing the size of snow drifts by removing snow fences
To retain topsoil and reduce soil erosion from wind and water these conservation practices can be taken
no-till planting, conservation tillage, contour farming, strip cropping, intercropping(alley), cover crops, Green manure crops, grassed waterways and gully control, shelterbelts and windbreaks, crop rotation, continuous cropping, and drip irrigation.
No-till Planting
where the new crop seeds (or small plants) are 'punched' down through the stubble of the preceeding crop
Conservation Tillage
reduced plowing keeps stubble on the ground.
Contour Farming
tillage and crops are run across the slope of the land, creating a slightly ridged surface that traps soil and water. It is NOT effective on slopes of > 8%(use terracing for those)
Strip Cropping
alternating strips of erosion-resistant crops (like forage crops or fallow grass strips) with erosion-prone crops (most food staple crops - wheat, corn, rice, etc.)
Intercropping (Alley)
growing crops in between rows of trees
Cover Crops
forage crops (alfalfa, clover, wheatgrass)
Green Manure Crops
legume crops (clover, soybeans, peas, beans) return nitrogen to the soil
Grassed Waterways and Gully Control
shallow but broad grassy strips that can divert water from the field; gully control can be met with small 'check dams'
Shelterbelts and Windbreaks
Windbreaks are a row of trees; Shelterbelts consist of 3 rows - one of shrubs, a second of trees, and the third can be a mixture of both
Crop Rotation
growing a different type of crop in a rotation of 3 or 4 different crops
Continuous Cropping
not allowing the soil to remain fallow during any part of the year. Use a cover crop or green manure crop during times that you might ordinarily leave fallow
Drip Irrigation
water is slowly dripped through a ground laid irrigation system instead of aerial spraying that has a large portion of the water evaporate before it ever reaches the soil
the processes created while trying to farm on marginal land (arid or semi-arid) so that crops yield less than 10%
Processes leading to desertification
1)overgrazing, 2)deforestation, 3)surface mining, 4)no irrigation control, 5)salinization, 6)continued farming on marginal land, 7)soil compaction.
Consequences of desertification
1)worsening drought, 2)famine, 3)decline in the standard of living, 4)more refugees.
Inorganic vs Organic (Manure) Fertilizers
1)Humus from organic aids in water retention (natural soil moisture), 2)Humus is bulkier providing more air spaces. Inorganic don't so there is more soil compaction. 3)Fewer air spaces in compacted soil = less O2 content = less absorption of I. fertilizer in soil 4)I. fertilizers only contain 2-3 of the 20 needed nutrients for plants. Manure contains almost all. 5)I. fertilizers cost more due to productions, transportation, and application 6)I. fertilizers cause more water pollution from excess applications 7)I. fertilizers release N2O (a greenhouse gas) 8)I. fertilizers contain high levels of NO3- which causes blue-baby syndrome.
Soil Erosion
3 types of erosion - sheet, rill, gully
Farming Methods
1)Traditional - 1830's, 2)Modern Intensive (Green Revolution and current time period), 3)Organic (Sustainable - uses the best of both)
Guidelines to create a more Sustainable agriculture
1)Use of native plants that have high resistance to crop infestations & diseases, 2)Grow more perennial crops 3)Use IPM practices for water (drip irrigation, drought resistant plants) 4)Shift to an energy saving (possibly more labor intensive) crop management 5)Phase out old crop subsidies & subsidize organic farming practices 6)Establish training and education programs for farmers & home gardeners to increase awareness 7)Protect existing cropland by using soil conservation practices ( no-till, intercropping, strip cropping, contour plowing, green manure, cover crops, etc) 8)Increase the use of organic fertilizers and biological & other controls instead of pesticides 9)Shift to "full-cost" pricing that includes environmental costs as well as production, transportation & application costs of the farmer.
Food & Drug Act
Delaney Clause -Forbid the addition of any amount of known carcinogens to food and drugs, based on the assumption that any exposure represented unacceptable risks
Federal Pesticide and Control Act -Required the registration of all pesticides
Toxic Substances Control Act
Authorized the EPA to ban or regulate chemicals deemed a risk to health or the environment
Federal Insecticide, Fungicide, and Rodenticide Act -Requires all commercial pesticides be approved by the EPA for general (over the counter) or restricted use (by trained professionals). The EPA is responsible for registering or licensing all pesticides. -Requires the EPA to test the pesticides and determine whether they cause any health risks (cancers, reproductive effects) .(After 25 years less than 10% have been tested due to lack of funding and manpower) -The EPA sets a tolerance level for the amount of residue that can remain on a crop when it gets to the grocery store (the levels are set for adults and not children)
Federal Food, Drug, and Cosmetic Act -Establishes the tolerances of pesticides for food and feed products. The FDA is responsible for administering this Act.
Food Quality Protection Act (amended both FIFRA and FFDCA) -Requires new tougher standards for pesticide tolerance levels in foods based on a reasonable certainty of no harm to human health through dietary exposure and drinking water. (this replaced the Delaney Clause) -Requires manufacturers to demonstrate that active ingredients are safe for infants and children. -Allows the EPA to apply an additional 10-fold safety factor for children on dose amounts -Allows the EPA to consider exposure to more than one pesticide when setting pesticide tolerance levels
Safe Drinking Water Act -To protect the quality of drinking water in the US for both underground and surface water. The EPA sets the standards for certain chemicals. -It requires a testing program for chemicals and pesticides for possible endocrine disrupting effects.
Comprehensive Environmental Response, Compensation and Liability Act -Created a "Superfund" for emergency response, spill prevention, and site remediation for toxic wastes. -Established the liability for clean up costs of the superfund sites
insecticides, herbicides, fungicides, nematocides, and rodenticides
Major kinds of Insecticides
chlorinated hydrocarbons (banned in US), organophosphates, carbamates, botanicals
broad spectrum herbicides
toxic to pests and non pests alike (kills all living things)
selective or narrow spectrum pesticides
toxic to specific group of pests only. Example: soap is a selective pesticide because it will kill (through dessication) only soft-bodied insects leaving those with hard shells (carapace) like ladybugs alone
Pesticide benefits
1)Saves human lives - from such insect borne diseases such as malaria, bubonic plague, and sleeping sickness. 2)Increase food supplies and lower food costs - about 55% of potential food supply is lost to pests before (35%) or after (20%) harvest. 3)Increase profits for farmers - for every $1 spent on pesticides leads to an increase in US crop yields worth $4. 4)Work faster and better than alternatives - long shelf life, are easily shipped and applied, and safe when handled properly. 5)The health risks of pesticides are insignificant compared with their health benefits and other benefits. 6)Many new pesticides are used at very low rates per unit area compared to older products - approx. 100x lower than older ones
The IDEAL pesticide would
1)Kill ONLY the target pest. 2)Harm NO other species. 3)Break down into harmless compounds soon after being applied (days)-NO persistence. 4)Not cause genetic resistance in target pests. 5)Be inexpensive
Pesticide Problems
1)Genetic resistance by pests -within 5-10 years pests can develop immunity -they breed a lot! 2)Broad spectrum insecticides kill natural predators and parasites that may have been maintaining the pop of pest species. 3)Wiping out natural predators can also unleash new pests whose pop the predators had previously held in check - 100-300 secondary pests have been escalated to major pest status due to insecticides. 4)Some pesticides bioaccumulate leading to disastrous problems for higher organisms. 5)There is a correlation between human health disease and pesticides though no direct link (epidemiology). They produce a variety of health problems (cancers, nervous disorders, reproductive disorders) in both animals and humans
Symptoms of Pesticide Poisoning
headaches, nausea, cramps, blurred vision, slowed heartbeat, muscle rippling, seizures, death
Chlorinated hydrocarbons
an organic compound containing chlorine. DDT is one. They are broad-spectrum insecticides. They are slow to degrade and so persist in the environment (in organisms as well as in nature) for years. Most have been banned since the advent of Rachel Carson's book, Silent Spring.
organic compounds that contain phosphorus and were created from German nerve gas. Malathion is an example. They are more poisonous than other insecticides and they are toxic to other animals other than insects, especially humans. They do NOT persist in the environment as long as chlorinated hydrocarbons. They are used in large scale agriculture but are not available to the consumer because of the toxicity of them. Those who work with them in agriculture have to attend classes to learn how to use them and also protect themselves while spraying.
derived from carbamic acid. They are broad-spectrum insecticides and are not as toxic as organophosphates to humans though they do show broad, non-target toxicity. Sevin dust is an example.
derived from plants. These are more pest specific and easily degrade in the environment and have a low toxicity level. Nicotine, pyrethrum, and rotenone are examples. Botanicals are easily degraded by microorganisms and so do not persist in the environment.
Grass (herbicide)
only kill grasses but are safe most other plants
Selective (herbicide)
kill only specific vegetation 2,4-D and 2,4,5-T are examples
Broad-leaf (herbicide)
kills those plants with broad-leaves but not grasses. These are similar in structure to a natural growth hormone in plants and disrupt the plant's natural growth processes. In otherwords they will kill dandelions but not grasses. Wheat, corn, and rice are considered grasses so these herbicides can be used on weeds growing amongst the grains.
Agent Orange
(used in the Vietnam war to defoliate trees so the enemy could more easily be spotted) contained an combination of 2,4-D and 2,4,5-T plus a minute portion of dioxins (a chlorinated hydrocarbon). These dioxins cause birth defects in animals and humans as well have been associated with some cancers.
Pesticide treadmill
when farmer increase the amount of pesticide sprayed on their crops due to increased genetic resistance Greater amounts of pesticide have been shown to be ineffective in combating increased pest problems. More food is lost to pests today (37%) than in 1940 (31%) even though more 10x the pesticides are being used.
the build up of pesticides through the food chain. Since the pesticide is stored in the fatty tissue of organisms it will be passed on when the organism is eaten, thus accumulating in each higher trophic level. The physical effects that arise from this is called biomagnification.
IPM - Integrated Pest Management
each crop and its pests are evaluated as parts of an ecological system. Then a control program is developed that includes a mix of cultivation and biological and chemical methods applied in proper sequence and with the proper timing. A well designed IPM program can reduce pesticide use and pest control costs by 50-90%. It can improve crop yields, reduce inputs of fertilizer and irrigation water, and slow the development of genetic resistance because pests are assaulted less often and with lower doses of pesticides. Widespread use of IPM is hindered by government subsidies of conventional chemical pesticides and by opposition from agricultural chemical companies.
Methods of controlling pests
1)Crop rotation 2)A barrier that surrounds the crop that provides a habitats for the pests natural enemies (ladybugs, spiders) 3)Biological control through natural predators of pests 4)Changing planting times so that pests either starve or are eaten by their natural enemies 5)Trap crops can be planted that lure pests away from the main crop 6)Light boxes (bug zappers), Bug bags 7)Practice intercropping, alley cropping, polyculture, polyvariety 8)Cultivate crops that are resistant to certain pest insects 9) Introduction of pesticides that are made from plants that can disrupt metabolism 10)Introduction of microbes (such as Bt - a bacillus) to disrupt metabolism in pests 11)Use of hormones to disrupt the growth or reproductive cycle of pests or sterilization of insects 12) Irradiation of food crops after harvesting 13)Monitor crops for infestations & then Only spray when & where necessary 14)Plant natural herbs that pests have a natural aversion to- cayenne, mint, bay leaves, basil, marigold, boric acid, diatomaceous earth 15)Spraying with botanicals or soap.
Regulatory agencies responsible for providing consumer protection
Department of Health and Human Services' (DHHS) Food and Drug Administration (FDA), U.S. Department of Agriculture's (USDA) Food Safety and Inspection Service (FSIS), Environmental Protection Agency (EPA), USDA's Animal and Plant Health Inspection Service (APHIS).
Department of Health and Human Services' (DHHS) Food and Drug Administration (FDA)
The FDA is charged with protecting consumers against impure, unsafe, and fraudulently labeled food other than in areas regulated by FSIS. They are also are responsible for periodically testing foods for pesticides.
U.S. Department of Agriculture's (USDA) Food Safety and Inspection Service (FSIS)
FSIS has the responsibility for ensuring that meat, poultry, and egg products are safe, wholesome, and accurately labeled.
USDA's Animal and Plant Health Inspection Service (APHIS)
APHIS' primary role in the U.S. food safety network of agencies is to protect against plant and animal pests and diseases.
Environmental Protection Agency (EPA)
EPA's mission includes protecting public health and the environment from risks posed by pesticides and promoting safer means of pest management.
3 agencies oversee the regulating of pesticides in different areas
EPA, FDA, and the USDA
POPs (Persistent Organic Pollutants)
man made chemicals that do NOT break down in the environment over a long period of time (years) and also bioaccumulates throughout the food web
POPs fall into 3 broad categories
1)pesticides (primarily insecticides) 2)industrial chemicals 3)by-products & contaminants ** Lead, Cadmium, and Mercury are usually included in the group, not because they are organic (they are NOT - they are metals) but because they persist and bioaccumulate and have serious health effects
Category: Insecticide, Human Health Effects: Liver cancer, damage to nervous system & reproductive system Exposure by: Breast milk, eating foods where it has bioaccumulated through the food web
Category: Industrial Chemical, Human Health Effects: Liver & kidney damage, thyroid damage, cancer, stomach damage Exposure by: Breast milk, eating foods where it has bioaccumulated through the food web
Category: By products Human Health Effects: Hormone system changes, reduced reproductive capacity & organ damage, immunosupression, chloracne. Exposure by: Incineration of waste material, copper smelting, burning trash, land application of sewage sludge, chlorine pulp bleaching
Lead (tetraethyl & tetramethyl)
Category:Inorganic toxic heavy metal, Human Health Effects: Anorexia, insomnia, tremor, nausea, mood disorders, memory impairment, death, Exposure: Ingestion or inhalation of exhaust (from cars) (banned from the US)
Category: Inorganic toxic heavy metal, Human Health Effects: Lung & prostate cancer, kidney damage, emphysema, osteoporosis, anemia, Exposure: TV, mechanical equipment, industrial painted surfaces.
Category:Inorganic toxic heavy metal, Human Health Effects: Cancer, stomach & l.intestine, brain, kidneys, lung damage, increased heart rate, "Mad Hatter's disease", Exposure: Eating contaminated fish & shellfish, incineration of waste material
Dust Bowl (1926 - 1934)
The grasses of the Midwest (Kansas, Oklahoma, Colorado, New Mexico) that had a complex root system were replaced by monoculture crops with simple root systems. Added to this change was the common practice of plowing the field after the harvest, leaving the soil exposed to strong winds during the winter months. The farming practices were changed with the Soil Erosion Act of 1935 that lead to the Soil Conservation Service (now named Natural Resources Conservation Service as part of the USDA). It promoted conservation practices such as contour plowing, crop rotation, conservation plowing, terracing, and windbreaks.
Major harmful effects of soil erosion
1)Loss of soil fertility increasing the use of inorganic fertilizers 2)Loss of soil's ability to hold water increasing the use of irrigation 3) Runoff of sediment - kills fish (clogging gills), suffocating benthic organisms, decreased photosynthesis of phytoplankton, clog ditches & waterways
Requirements of a Green Revolution
1)Monoculture crops of GM crops - usually annuals. 2)High input of : Inorganic fertilizers, Irrigation, Energy from machinery, Pesticides, 3)Multiple cropping (plantings in one year)
Pros of the GR
1)High yield from crops 2)Increased food reserves for world 3)Enhanced learning and effectiveness of GM crops
Cons of the GR
1)High cost of equipment 2)Excessive use of water 3)Increased salinization 4)Excessive use of inorganic fertilizers 5)Compaction of soil due to lack of humus 6)Less natural resistance to pests with hybrid GM crops 7)Excessive use of pesticides 8)Increased pest resistance to pesticides
Newer soil conservation methods
strip cropping, alley cropping, shelterbelts, gully reclamation, cover crops, green manure
Strip cropping
planting alternating strips of one crop with another crop (i.e. corn with legume) The second crop (legume) traps the eroding soil from the first crop (corn) as well as trapping water and also providing a barrier to pests.
Alley cropping (agroforestry)
several crops are planted together in strips or alleys between trees and shrubs that provide fruit or fuelwood. The trees provide shade which reduces evaporation of precious water so that soil moisture is retained as well as providing fruit or fuel (if only dead limbs are cut).
a wider area than a windbreak that contains trees as well as shrubs to help reduce wind erosion, retain soil moisture, provide habitats for wildlife and fuel.
Gully reclamation
restoring severely eroded land by planting shrubs, vines, & trees to stabilize the soil, channels to divert fast moving water, and check dams that will fill up with silt and gradually fill in the gullies.
Cover crops
grasses or legumes that are planted at the end of a harvest so that the soil is not left exposed during the none growing season. These 'crops' can either be harvested for animal fodder or plowed under to help fertilize the soil before the next growing season.
Green Manure
legumes are planted and then plowed under to put nitrogen back into the soil.
Pros of Organic Fertilizers
improves soil structure; adds organic nitrogen; stimulates beneficial soil bacteria & fungi; adds organic nutrients to soil
Cons of Organic Fertilizers
high cost of transporting it to crop growing farms from feedlots
Pros of Inorganic Fertilizers
contains N, P, and K (3 main minerals needed in growth); easily transported, stored & applied
Cons of Inorganic Fertilizers
doesn't add humus to soil so soil is drier, needing more irrigation; lowering oxygen content of soil which reduces the efficiency of nutrient uptake; releases nitrous oxide (N2O) which enhances global warming; requires a great deal of energy to produce and apply (the cost of equipment!) than organic fertilizer.
Methods to Increase Soil Fertility
1)Manure 2)Green manure 3)Compost 4)Mycorrhizae fungi that are found in the spores attached to the roots of plants (help in disease resistance & nutrient uptake).
Methods to decrease Soil Erosion
Contour farming, Minimum-tillage farming (Conservation tillage), No-till farming, Terracing, Strip cropping, Cover crops, Alley cropping (agroforestry), Grassed waterways & gully control, Planting perennial crops, Using drip irrigation vs conventional irrigation, Windbreaks, Shelterbelts, Land classifications that establish what lands are farmable due to slope, Stubble mulching, Snow management.
Methods to decrease Salinization
Use of salt tolerant crops, Use of drought resistant crops, Flexible cropping (fallow land), Planting Deep-rooted crops, Snow management, Increase surface drainage in low-lying areas, Irrigation methods that use less water, Drip irrigation, Center pivot irrigation, LEPA sprinklers.
Methods to INCREASE Soil Fertility & Crop Production
Adding manure, Polyvarietal cultivation, Polyculture, Alley cropping, Intercropping, Strip cropping, Green manure cover crops, Increasing the amount of humus in soil, Adding compost to soil, Crop rotation.
Methods to decrease use of Pesticides
Strip cropping, Alley cropping, Bio-pesticides (i.e. soap), Biological pest control, Light boxes, Polyculture, Insect birth control and/or hormones, GM resistant crops, Pheremones to attract pests (i.e. Japanese Beetle traps), Hot water, Spraying only when and where a pest outbreak occurs, Crop rotation, A barrier hedge that surrounds the crop that provides a habitat for the pest's natural enemies, Changing planting times so that pests either starve or are eaten by their natural predators, Trap crops that can lure pests away from the main crop, Introduce microbes (like Bt thurengensis) to disrupt the metabolism of pests, Use of IPM.
ecological definition of soil
a mixture of mineral particles, organic matter, water and air that is capable of supporting plant life.
Physical Weathering
the breakdown of rock (the regolith) into finer particles through weathering.
Chemical Weathering
the breakdown and redeposition of organic and inorganic substances primarily through the processes of oxidation, dissolving, and leaching.
the breakdown of organic matter by bacteria and fungi into simpler organic substances (carbohydrates, lignins, proteins)
the ultimate breakdown of organic substances into nonorganic substances(minerals, carbon dioxide, water, salts)
the transformation by soil bacteria of ammonia compounds into nitrates and nitrites.
new soils with little horizon development (soilds on floodplains, sand dunes, mountain tops, etc)
shallow moderately developed soils on new, very cold, or very wet substrates (ex. many tundra soils)
organic soils, peats.
Grassland soils
young soils
entisols, inceptisols, histosols
praire soils and soils with dark surface horizons, high in organic matter and high base saturation.
Deciduous forest soils
spodosols, alfisols
highly leached soils with a distinct bleached (E) horizon
well developed, soils common in many midwestern deciduous forests
Desert and Tropical soils
vertisols, ardisols, ultisols, oxisols
soils high in clay and salts that crak deeply when dried (many desert soils)
red desert soils, highly oxidized
intensely leached soils of warm climates with strong clay translocation, and low base content
highly weathered soils of the tropics with high oxides
Any food or element an organism must take in to live, grow, or reproduce.
organic farming
Producing crops and livestock naturally by using organic fertilizer (manure, legumes, compost) and natural pest control (bugs that eat harmful bugs, plants that repel bugs, and environmental controls such as crop rotation) instead of using commercial inorganic fertilizers and synthetic pesticides and herbicides. See sustainable agriculture.
organic fertilizer
Organic material such as animal manure, green manure, and compost, applied to cropland as a source of plant nutrients. Compare commercial inorganic fertilizer.
Destruction of vegetation when too many grazing animals feed too long and exceed the carrying capacity of a rangeland or pasture area.
Diet so high in calories, saturated (animal) fats, salt, sugar, and processed foods and so low in vegetables and fruits that the consumer runs high risks of diabetes, hypertension, heart disease, and other health hazards. Compare malnutrition, undernutrition.
Managed grassland or enclosed meadow that usually is planted with domesticated grasses or other forage to be grazed by livestock. Compare feedlot, rangeland.
Plant that can live for more than 2 years. Compare annual.
plantation agriculture
Growing specialized crops such as bananas, coffee, and cacao in tropical developing countries, primarily for sale to developed countries.
Complex form of intercropping in which a large number of different plants maturing at different times are planted together. See also intercropping. Compare monoculture, polyvarietal cultivation.
polyvarietal cultivation
Planting a plot of land with several varieties of the same crop. Compare intercropping, monoculture, polyculture.
Land that supplies forage or vegetation (grasses, grasslike plants, and shrubs) for grazing and browsing animals and is not intensively managed. Compare feedlot, pasture.
riparian zones
Thin strips and patches of vegetation that surround streams. They are very important habitats and resources for wildlife.
Accumulation of salts in soil that can eventually make the soil unable to support plant growth.
See windbreak.
soil conservation
Methods used to reduce soil erosion, prevent depletion of soil nutrients, and restore nutrients already lost by erosion, leaching, and excessive crop harvesting.
soil erosion
Movement of soil components, especially topsoil, from one place to another, usually by wind, flowing water, or both. This natural process can be greatly accelerated by human activities that remove vegetation from soil.
strip cropping
Planting regular crops and close-growing plants, such as hay or nitrogen-fixing legumes, in alternating rows or bands to help reduce depletion of soil nutrients.
subsistence farming
Supplementing solar energy with energy from human labor and draft animals to produce enough food to feed oneself and family members; in good years enough food may be left over to sell or put aside for hard times. Compare industrialized agriculture.
surface runoff
Water flowing off the land into bodies of surface water. See reliable runoff.
sustainable agriculture
Method of growing crops and raising livestock based on organic fertilizers, soil conservation, water conservation, biological pest control, and minimal use of nonrenewable fossil-fuel energy.
Planting crops on a long, steep slope that has been converted into a series of broad, nearly level terraces with short vertical drops from one to another that run along the contour of the land to retain water and reduce soil erosion.
traditional intensive agriculture
Producing enough food for a farm family's survival and perhaps a surplus that can be sold. This type of agriculture uses higher inputs of labor, fertilizer, and water than traditional subsistence agriculture. See traditional subsistence agriculture. Compare industrialized agriculture.
traditional subsistence agriculture
Production of enough crops or livestock for a farm family's survival and, in good years, a surplus to sell or put aside for hard times. Compare industrialized agriculture, traditional intensive agriculture.
Reduction of the net primary productivity of grassland vegetation and grass cover from absence of grazing for long periods (at least 5 years). Compare overgrazing.
Consuming insufficient food to meet one's minimum daily energy needs for a long enough time to cause harmful effects. Compare malnutrition, overnutrition.
Saturation of soil with irrigation water or excessive precipitation so that the water table rises close to the surface.
Row of trees or hedges planted to partially block wind flow and reduce soil erosion on cultivated land.
Complex mixture of inorganic minerals (clay, silt, pebbles, and sand), decaying organic matter, water, air, and living organisms.
soil horizons
Horizontal zones that make up a particular mature soil. Each horizon has a distinct texture and composition that vary with different types of soils.
soil permeability
Rate at which water and air move from upper to lower soil layers.
soil profile
Cross-sectional view of the horizons in a soil. See soil horizon.
soil structure
How the particles that make up a soil are organized and clumped together. See also soil permeability, soil texture.
soil texture
Relative amounts of the different types and sizes of mineral particles in a sample of soil.
Amount of various salts dissolved in a given volume of water.
Percentage of space in rock or soil occupied by voids, whether the voids are isolated or connected
The degree to which underground rock and soil pores are interconnected and thus a measure of the degree to which water can flow freely from one pore to another.
Process in which various chemicals in upper layers of soil are dissolved and carried to lower layers and, in some cases, to groundwater.
biological pest control
Control of pest populations by natural predators, parasites, or disease-causing bacteria and viruses (pathogens).
chlorinated hydrocarbon
Organic compound made up of atoms of carbon, hydrogen, and chlorine. Examples are DDT and PCBs.
Dichlorodiphenyltrichloroethane, a chlorinated hydrocarbon that has been widely used as an insecticide but is now banned in some countries.
Chemical that kills fungi.
Chemical that kills a plant or inhibits its growth.
Chemical that kills insects.
integrated pest management (IPM)
Combined use of biological, chemical, and cultivation methods in proper sequence and timing to keep the size of a pest population below the size that causes economically unacceptable loss of a crop or livestock animal.
Unwanted organism that directly or indirectly interferes with human activities.
Any chemical designed to kill or inhibit the growth of an organism that people consider undesirable. See fungicide, herbicide, insecticide.
polychlorinated biphenyls (PCBs)
Group of 209 different toxic, oily, synthetic chlorinated hydrocarbon compounds that can be biologically amplified in food chains and webs.