Ch. 9 APES Review - Soil and Agriculture, Envir 130 ch 10
Composition of soil
-50% mineral matter -Up to 5% organic matter (dead and living microorganisms, decaying material from plants and animals) -The remainder is pore space taken up by air and water -Soil is teeming with bacteria, algae, fungi, and protists and provides habitat for earthworms, insects, mammals, reptiles, and amphibians -Since soil is composed of interacting living and nonliving matter, it is considered an ecosystem
Cropland vs. rangeland/pasture
-Cropland: land used to raise plants for human use -Rangeland/pasture: land used for grazing livestock -Land devoted to agriculture covers 38% of Earth's land
Erosion threatens ecosystems and agriculture
-Erosion = removal of material from one place to another by wind or water -Deposition = arrival of eroded material at a new location -Flowing water deposits nutrient-rich sediment in river valleys and deltas -Floodplains are excellent for farming -Erosion occurs faster than soil is formed -It tends to remove topsoil—the most valuable layer for plant growth -Windy regions with sparse plant cover suffer from wind erosion -Areas with steep slopes, high precipitation, and little plant cover suffer from water erosion -Land is made more vulnerable to erosion through: -Overcultivating fields through poor planning or excessive tilling -Overgrazing rangelands -Clearing forests on steep slopes or with large clear-cuts -U.S. croplands lose about 2.5 cm (1 in.) of topsoil every 15-30 years -Erosion can be hard to detect and measure
Sustainable fertilizer use
-Nutrients can be added to drip irrigation and are delivered directly to the plants -No-till planting allows the application of fertilizers with the seeds rather than spreading it across the soil -Monitoring of soil nutrients can prevent unneeded applications -Organic fertilizers provide needed nutrients as well as improving the soil by improving soil structure, increasing nutrient-holding capacity, and increasing water-retaining capacity
Wetlands
-Over 50% of wetlands (swamps, marshes, bogs, river floodplains) have been drained for agriculture in the U.S. -Government policy encouraged draining (Swamp Lands Acts drained and converted wetlands to control floods and malaria) -Wetlands are now seen as vital ecosystems (habitat, flood control, recharged water supplies) -Despite regulations, loopholes allow wetland losses -Wetlands Reserve Program: landowners are paid to protect, restore, and enhance wetlands
Zinc deficiency symptoms
-Pale bands located between the veins of the leaves -Stunted growth -Associated with soils that are alkaline and contain little organic material
Nitrogen deficiency symptoms
-Plant yellows -Stunted and spindly -Can result after heavy rains remove nitrogen from sandy soils
Regional soil differences affect agriculture
-Soil characteristics vary from place to place -In rainforests the nutrients are in plants, not the soil -Rain leaches minerals and nutrients, reducing their accessibility to roots -Rapid decomposition of leaf litter results in a thin topsoil layer with little humus Swidden agriculture: traditionally used in tropical areas -After cultivation, a plot is left to grow back into forest -Soils are depleted if not enough time is given -Temperate prairies have lower rainfall and less nutrient leaching and are able to build rich topsoil
Soil Conservation Service
-Started in 1935, the Service works with farmers to develop conservation plans for individual farms -Conservation districts = districts that promote soil conservation practices at the county level -> Operate with federal direction, authorization, and funding and are organized by the states -In 1994, the Service was renamed Natural Resources Conservation Service (NRCS) -> Responsibilities expanded to also include water quality protection and pollution control -These serve as models for efforts around the world -The majority of farmland in Argentina, Brazil, and Paraguay uses no-till farming (resulted from grassroot farmers' organizations, helped by agronomists and government extension agents)
Phosphorus deficiency symptoms
-Stunted growth -Mature later than healthy plants -> more susceptible to frost, harvest damage, disease infection, and summer drought -Leaves and stems purple and redden -Can result when roots have trouble entering compacted soil or if they are damaged by insects
Potassium deficiency symptoms
-Stunted growth -Yellowing and drying of leaf edges -Dark discoloration of leaves because of the death of cells -Weak stems that often break below the ears -Most often occurs in soils that are sandy, wet, or compacted
Farmer-Centered Agricultural Resource Management Program (FARM)
-Within the Food and Agriculture Organization (FAO), which is the United Nations' main agriculture program -Supports innovative approaches to resource management and sustainable agriculture in Asia -Helps farmers duplicate agricultural success stories -Uses local communities to educate and encourage farmers to conserve soils and secure the food supply
Soil structure
A measure of soil's clumpiness -A medium amount of clumpiness is best for plants -Repeated tilling compacts soil, decreasing its water-absorbing capabilities
22) It is more energetically efficient for us to eat more ________. A) plant-based foods B) herbivorous animals like cattle and chicken C) carnivorous animals like fish and alligator D) GM foods E) foods grown using IPM methods
Answer: A Section: 10.2 Bloom's Taxonomy: Knowledge/Comprehension
5) Raising which of the following requires the most land and water per kg protein produced? A) beef cattle B) dairy cattle C) chickens D) pigs E) goats
Answer: A Section: 10.2 Bloom's Taxonomy: Knowledge/Comprehension
14) Which of the following best describes integrated pest management (IPM)? A) biocontrol measures, crop rotation, and habitat diversification B) major reliance on synthetic pesticides C) subsidies for pesticide use D) continuous monoculture cropping and harvesting E) transgenic crops
Answer: A Section: 10.4 Bloom's Taxonomy: Knowledge/Comprehension
2) In Queensland, Australia, cactus moths ________. A) effectively cleared non-native prickly pear cactus from rangeland B) are an invasive species C) are raised as a food source by native Aborigines D) are examples of species that have developed resistance to pesticides E) are a keystone species
Answer: A Section: 10.4 Bloom's Taxonomy: Knowledge/Comprehension
23) Why did the Indonesian government support IPM for agriculture in 1986? A) Pesticides were costing money, causing pollution, and decreasing yields. B) Many people were dying of starvation. C) It wanted to encourage research into genetically modified crops. D) The country was in a recession. E) They were worried about tsunamis.
Answer: A Section: 10.5 Bloom's Taxonomy: Knowledge/Comprehension
4) Why have most bioengineered crops been modified for "resistance" traits? A) These traits have the economic potential to save on production costs. B) No technology exists to engineer other traits successfully. C) These are the only traits proven safe for the environment. D) These are the only traits proven safe for the human health. E) Crops with these traits taste better.
Answer: A Section: 10.6 Bloom's Taxonomy: Application/Analysis
9) Oaxaca, Mexico ________. A) is a world center of biodiversity for maize B) has more poverty than any other place in the world C) is known for successful organic farming D) is where the Green Revolution was launched E) is where the gene revolution was launched
Answer: A Section: 10.6 Bloom's Taxonomy: Knowledge/Comprehension
7) Why is resistance to pesticides likely to occur over time when they are used in agriculture?
Answer: A small fraction of large pest populations may have genes that confer some degree of immunity to a given pesticide. If very few resistant pests survive, they may reproduce quickly and create a new population of genetically resistant pests because their population is no longer balanced by the susceptible individuals. The pesticide will not be effective against this new resistant pest population. Section: 10.4 Bloom's Taxonomy: Knowledge/Comprehension
15) People around the world have become more dependent on global markets for their food. As a result, recent U.S. government policies encouraging ________ have had a major negative effect on food availability. A) organic farming B) ethanol production C) permaculture techniques D) integrated pest management E) increased herbicide use
Answer: B Section: 10.1 Bloom's Taxonomy: Knowledge/Comprehension
16) Plants with showy flowers typically ________. A) are pollinated by wind B) are pollinated by animals C) are genetically modified by animals D) are preferentially eaten by herbivorous animals E) decrease biodiversity in an area
Answer: B Section: 10.4 Bloom's Taxonomy: Knowledge/Comprehension
24) In order for livestock to be considered organic, ________. A) hormones and antibiotics are permitted, but not vaccines B) animals must be fed 100% organic agricultural feed C) animals cannot be transferred from regular treatment to organic standards D) no vitamins and mineral supplements can be used E) animals must be reared under natural conditions in intact ecosystems
Answer: B Section: 10.5 Bloom's Taxonomy: Knowledge/Comprehension
5) If GM crops can decrease pesticide use, why are environmentalists still concerned about them? A) The FDA does not regulate them. B) Inserted genes can spread to nontarget species. C) The government funds most GM crop research. D) Trials involving biotech fruits and vegetables have increased dramatically in recent years. E) There is no public opposition to GM crops.
Answer: B Section: 10.6 Bloom's Taxonomy: Application/Analysis
2) The Flavr Savr tomato is no longer marketed because ________. A) Calgene failed to attain government approval to market it B) people were nervous about eating genetically modified tomatoes C) genetically modified crops presently are not approved for sale in the United States D) butterfly larvae that ate the tomato plants were poisoned E) they require too much water to grow
Answer: B Section: 10.6 Bloom's Taxonomy: Knowledge/Comprehension
20) The Cartagena Protocol on Biosafety ________. A) regulates the creation of GM foods B) outlines regulations on international trade of GM foods C) was signed by the United States D) regulates trading of endangered species E) prohibits irradiation of food crops
Answer: B Section: 10.6 Bloom's Taxonomy: Knowledge/Comprehension
11) Green Revolution techniques ________. A) focus on organic farming B) have contributed to an increased diversity of foods in the human diet C) have increased crop yields but may not be sustainable D) focus on preserving biodiversity E) focus on sustainability
Answer: C Section: 10.1 Bloom's Taxonomy: Knowledge/Comprehension
13) Agricultural productivity increased during the Green Revolution as a result of improvements in fertilizers, crop breeding, pest control, and ________. A) techniques to convert land for agriculture B) weather conditions C) irrigation D) organic farming techniques E) fossil fuel use
Answer: C Section: 10.1 Bloom's Taxonomy: Knowledge/Comprehension
1) The figure demonstrates that it requires roughly ________ times more feed input to produce 1 kg of eggs than 1 kg of milk. A) 2 B) 3 C) 4 D) 7 E) 45
Answer: C Section: 10.2 Bloom's Taxonomy: Application/Analysis
8) Which of the following requires the least land to produce 1 kg of protein? A) beef and pork B) milk C) chicken D) pork E) beef
Answer: C Section: 10.2 Bloom's Taxonomy: Knowledge/Comprehension
21) Seed banks are important for ________. A) agricultural investments in developing countries B) protecting monoculture productivity C) protecting genetic diversity D) loans to developing countries to promote organic agriculture E) providing farmers with the current year's GM crops
Answer: C Section: 10.3 Bloom's Taxonomy: Knowledge/Comprehension
6) Researchers in Switzerland have demonstrated that organic farming ________. A) is only sustainable with pesticides and synthetic fertilizers B) presently has no market in Europe C) decreased organic soil losses while giving yields almost as high as conventional farming D) increases the incidence of invasive species E) suppresses the biodiversity of pollinating insects, especially bees
Answer: C Section: 10.5 Bloom's Taxonomy: Knowledge/Comprehension
26) Recent investigations of the impact of GM crops on biodiversity in Great Britain indicate that ________. A) biodiversity increased in all GM crop sites B) GM crop sites had catastrophically reduced biodiversity C) some GM crops and sites showed increased biodiversity, while others showed decreases D) birds and insects cannot digest GM crops E) none of the GM crop sites showed changes in biodiversity
Answer: C Section: 10.6 Bloom's Taxonomy: Knowledge/Comprehension
3) Recombinant DNA ________. A) is pollination of one plant by another of the same species B) is cross-pollination of one plant by a different species C) is the merging of DNA from unrelated organisms D) is assembled in the lab from mononucleotides E) was part of the Green Revolution of the 1960s
Answer: C Section: 10.6 Bloom's Taxonomy: Knowledge/Comprehension
7) Bt crops ________. A) have not yet been approved by the FDA B) include strawberries that are resistant to frost damage C) have been given a bacterial gene that gives chemical protection against insect pests D) have seeds that will only germinate under laboratory conditions E) are widely grown in Europe but have been banned in the United States
Answer: C Section: 10.6 Bloom's Taxonomy: Knowledge/Comprehension
28) In Japan, the presence of ducks and the aquatic fern Azolla in rice cultivation has shown that ________. A) invasive species diminish rice yields B) the ferns provide an excellent food for ducks C) restoring portions of the biodiversity of a natural ecosystem increases crop yields and profits D) ducks and other birds must be eliminated from rice fields E) GM crops such as rice cannot succeed without ferns to provide shade and ducks to provide pollination
Answer: C Section: 10.7 Bloom's Taxonomy: Knowledge/Comprehension
10) Which of the following is true? A) World hunger has increased significantly since 1970. B) Aquaculture has decreased significantly since 1985. C) World grain production has remained stable since 1985. D) More than one in three adults in the United States is obese. E) The main reason why people are undernourished is because they are not educated about proper nutrition.
Answer: D Section: 10.1 Bloom's Taxonomy: Knowledge/Comprehension
27) Normal Borlaug, who passed away in 2009, pioneered the development of ________. A) organic agriculture B) IPM C) GM crops D) high-yield wheat E) monoculture farming
Answer: D Section: 10.1 Bloom's Taxonomy: Knowledge/Comprehension
3) Cows require a high quantity of feed because they ________. A) are genetically modified organisms B) can feed more people than pigs C) are raised on feedlots D) take time to grow and have a low energy conversion efficiency E) are the best source of high-quality protein
Answer: D Section: 10.2 Bloom's Taxonomy: Application/Analysis
4) Managing crop competitors and pests has been challenging to agronomists for centuries. One approach, integrated pest management, ________. A) uses only synthetic chemical pesticides B) uses no pesticides of any kind C) uses only natural pesticides D) combines synthetic chemical pesticides with biocontrol techniques E) combines a variety of pesticides to combat the pest
Answer: D Section: 10.4 Bloom's Taxonomy: Knowledge/Comprehension
19) Organic farming ________. A) began in the 1960s B) has no national standards in the United States C) and organically grown produce have not been supported by the European Union D) has become more challenging because of contamination by GM crop varieties E) is presently limited to crops of fruits and vegetables
Answer: D Section: 10.5, 10.6 Bloom's Taxonomy: Knowledge/Comprehension
6) Presently, ________ have not supported the widespread marketing of GM crops. A) South American countries B) American corporations C) American regulatory agencies D) European countries E) Asian countries
Answer: D Section: 10.6 Bloom's Taxonomy: Knowledge/Comprehension
9) Briefly discuss some disadvantages of aquaculture.
Answer: Dense concentrations of farmed aquatic animals can increase the incidence of disease, which reduces food security, necessitates antibiotic treatment, and results in additional expense. Aquaculture can also produce high amounts of waste from the farmed organisms and from the large portion of feed that goes uneaten and decomposes in the water column. Farmed aquatic fish and other organisms are often fed grain or ocean-caught fish, affecting food supplies and wild fish populations. If farmed aquatic organisms escape where they are not native, they can cause unpredictable harm by spreading disease or outcompeting native organisms. Section: 10.2 Bloom's Taxonomy: Application/Analysis
1) Monoculture ________. A) agricultural practices require no synthetic fertilizers or pesticides B) farming is illegal in most countries C) describes diets low in protein, such as vegetarianism D) involves the farming of crops that have not been genetically modified E) agricultural practices increase a crop's susceptibility to insect pests
Answer: E Section: 10.1 Bloom's Taxonomy: Knowledge/Comprehension
2) The comparison shown in the figure is environmentally significant because it shows that ________. A) grain is a nonrenewable resource B) we cannot survive without eating the foods pictured C) the same grain used to feed chickens and cows could be fed to many humans instead D) cows are a keystone species E) production of beef and pork is resource-intensive
Answer: E Section: 10.2 Bloom's Taxonomy: Application/Analysis
1) Which of the following was a positive environmental aspect of the Flavr Savr tomato? A) could be shipped further B) better taste C) better appearance D) lower cost to the consumer E) less food waste because it is less likely to rot
Answer: E Section: 10.6 Bloom's Taxonomy: Application/Analysis
3) Why do soybeans, corn, and canola dominate the GM crop market? A) They are inexpensive to produce. B) They are exempt from U.S. regulations. C) They are the only GMO crops approved since the Flavr Savr tomato. D) These crops help to feed and clothe the poor. E) They are ingredients in processed foods, so they are more easily accepted.
Answer: E Section: 10.6 Bloom's Taxonomy: Application/Analysis
17) The European Union nations ________. A) have converted all farms to organic agriculture B) along with Canada, Brazil, and Argentina have developed and planted many GM crops C) have refused to allow synthetic pesticides to be used on nonexported crops D) produce so little food that they have to import most meats and vegetables E) do not support the growth or sale of GM crops
Answer: E Section: 10.6 Bloom's Taxonomy: Knowledge/Comprehension
Topsoil
Mixture of humus, clay, and other minerals that forms the crumbly, topmost layer of soil. -vital for agriculture
Land degradation
a general deterioration of land, decreasing its productivity and biodiversity -Erosion, nutrient depletion, water scarcity, salinization, waterlogging, chemical pollution
Waterlogging
experienced by overirrigated soils when the water table rises to cover and suffocates roots
Conservation Reserve Program
farmers are paid to put highly erodible land in conservation reserves -Each dollar spent saves 1 ton of topsoil -Generates income for farmers -Improves water quality -Provides habitat for native wildlife
Industrialized agriculture
form of agriculture that uses large-scale mechanization and fossil fuels to boost yields -Also uses pesticides, irrigation, and fertilizers -Monoculture = uniform planting of a single crop -increased our ability to obtain more food from the same area
transgenes
genes from another species
GMOS
genetically modified organisms
Crop rotation
growing different crops from one year to the next -Returns nutrients to soil -Prevents erosion, reduces pests -Like crop rotation, no-till farmers may alternate wheat or corn with nitrogen-fixing soybeans
Percolation
The downward movement of water through soil and rock due to gravity. -Soils which drain well will stay areated but they are not as stable as others -Soils which are more stable may not drain well, retain too much water, and negatively affect plant growth -ranking the three different soil textures from fastest to slowest percolation rate: 1) Sand 2) Humus 3) Clay
Desertification
a form of land degradation with more than a 10% loss of productivity -Caused primarily by wind and water erosion, but also by deforestation, soil compaction, overgrazing, drought, salinization, water depletion, and climate change -Arid and semiarid lands (drylands) are most prone to desertification (40% of the Earth's surface) -Endangers food supplies of 1 billion people -Costs tens of billions of dollars each year -Intensified by positive feedback: degradation forces farmers onto poorer land -> farmers reduce fallow periods, so land loses nutrients
Conservation tillage
strategies that reduce the amount of tilling relative to conventional farming -Leaves at least 30% of crop residues in the field -No-till farming disturbs the soil even less
Fertilizers
substances containing essential nutrients -Plants require nitrogen, phosphorus, and potassium and remove them from the soil, possibly limiting growth
Parent material
the base geologic material of soil -Lava, volcanic ash, rock, dunes -Bedrock = solid rock comprising the Earth's crust
Salinization
the buildup of salts in surface soil layers -worse in arid areas -evaporation pulls salts up from lower soil horizons
Soil profile
the cross-section of soil as a whole -Degree of weathering and amount of organic matter decrease in lower horizons
Organic fertilizers
the remains or wastes of organisms -Manure, crop residues, fresh vegetation -Compost = mixture produced when decomposers break down organic matter -Traditional agriculture relied on organic fertilizers
Inorganic fertilizers
mined or synthetically manufactured mineral supplements -The Green Revolution brought on increased use of inorganic fertilizers, which are more susceptible to leaching and runoff: -Runoff into surface waters far from the point of application, causing "dead zones" in water bodies -Nitrates volatilize (evaporate) into the air and contaminate groundwater -Nitrates and phosphates in drinking water can cause cancer and blue-baby syndrome in infants
Green Revolution
new technology, crop varieties, and farming practices were introduced to developing countries -Increased yields and decreased starvation -Degraded the integrity of the soil
Shelterbelts (windbreaks)
rows of trees planted along edges of fields to slow the wind -Can be combined with intercropping
Humus
spongy material formed by partial decomposition of organic matter; holds moisture
Terracing
cutting level platforms into steep hillsides -The steps of this "staircase" hold water
Horizon
each layer in a soil profile -O horizon: organic (litter layer) -A horizon: topsoil -E horizon: eluviated (leaching layer) -B horizon: subsoil (where leaching has deposited materials) -C horizon: weathered parent material -R horizon: rock (parent material) how to remember (lol): Only An Easy Bitch Cries Regularly
Porosity
Water-holding capacity -ranking the three different soil textures from highest porosity to lowest porosity: 1) Clay 2) Humus 3) Sand
How does soil support agriculture?
Agriculture and plants require healthy soil to -Provide nutrients -Have a structure that allows roots to penetrate deeply -Retain water Livestock depend on healthy soil because they depend on the plants that grow there Organic matter provides nutrients and helps with structure and water retention Soils that retain water but drain excess water make the right amount accessible to plants Nutrients such as nitrogen and phosphorus enable plant growth Soil structure and texture influence root penetration and growth
12) ________% of the food we consume comes from ________ crop species. A) 90; 15 B) 90; 100 C) 50; 20 D) 50; 50 E) 10; 100
Answer: A Section: 10.1 Bloom's Taxonomy: Knowledge/Comprehension
25) During the past half century, global food production has ________ world population growth. A) grown at a faster rate than B) fallen behind C) stayed about even with D) surpassed by several orders of magnitude E) fallen to critical levels compared to
Answer: A Section: 10.1 Bloom's Taxonomy: Knowledge/Comprehension
4) Based on the information in the figure, you might decide to make changes in your diet to diminish your ecological footprint by ________. A) shifting your protein intake from beef and pork to eggs and dairy products B) shifting your protein intake from eggs and dairy products to beef and pork C) shifting to beef exclusively because of the large amount of meat from a single cow D) shifting your protein intake to young cows and pigs to reduce resource consumption E) eliminating all protein from your diet
Answer: A Section: 10.2 Bloom's Taxonomy: Application/Analysis
18) Aquaculture ________. A) can bring economic benefits and food security to many developing regions B) has no real environmental disadvantages C) frequently results in unintended catch of nontarget species D) requires the flooding of fields to produce water-intensive crops such as cotton and rice E) produces less fish per unit area compared to ocean water harvesting
Answer: A Section: 10.2 Bloom's Taxonomy: Knowledge/Comprehension
What type of legislation has encouraged farmers to adopt soil conservation practices in order to receive government subsidies?
Farm bills -passed every 5-6 years to encourage soil conservation among U.S. farmers
Conserving soil
Feeding the world's rising human population requires changing our diet or increasing agricultural production -But land suitable for farming is running out Mismanaged agriculture turns grasslands into deserts, removes forests, diminishes biodiversity and encourages the growth of non-native species -It also pollutes soil, air, and water with chemicals -Fertile soil is blown and washed away We must improve the efficiency of food production while we decrease our impact on natural systems
What are some factors that influence soil formation?
Key processes: weathering and the accumulation/transformation of organic matter -Climate: soils form faster in warm, wet climates -Organisms: plants and decomposers add organic matter -Topography: hills and valleys affect exposure to sun, wind, and water -Parent material: influences properties of resulting soil -Time: soil can take decades to millennia to form
Soil erosion is a global issue
Humans are the primary cause of erosion -Human activities move over 10 times more soil than all natural processes combined Conservation farming decreases erosion rates over conventional agriculture -More than 19 billion ha (47 billion acres) of the world's croplands suffer from erosion and other forms of soil degradation resulting from human activity -In Africa, erosion could reduce crop yields by half in coming decades
1) Major pollinators of many flowering nongrain crop plants
I) bees Section: 10.4, 10.6 Bloom's Taxonomy: Knowledge/Comprehension
Soil color
Indicates its composition and fertility -Black or dark brown soil is rich in organic matter -Pale gray or white soil indicates leaching
Benefits of no-till farming
It increases organic matter and soil biota -Reduces erosion and improves soil quality -Uses less labor, saves time, causes less wear on machinery Prevents carbon from entering the atmosphere (carbon storage)—may help mitigate climate change -Reduces fossil fuel use due to less use of the tractors -Adds organic matter to soils that is kept from the atmosphere May require increased use of herbicides and fertilizers, but to minimize problems: -use green manure (dead plants as fertilizer) -rotate fields with cover crops
How can erosion be prevented?
Physical barriers to capture soil can prevent erosion Plants prevent soil loss by slowing wind and water flow -Roots hold soil in place -No-till agriculture leaves plant residue on fields -Cover crops protect soil between crop plantings
What is the key to erosion control?
Plant cover -Move livestock to prevent overgrazing -Cut fewer trees in an area rather than clear-cut -Plant vegetation along riverbanks and roadsides China's huge tree-planting program slows erosion, but the monocultures are not ecologically functioning forests
Irrigation
artificially providing water to support agriculture -Unproductive regions become productive farmland -Can grow water-intensive crops like rice and cotton -70% of all freshwater used by humans goes to irrigation -Can deplete aquifers and dry up rivers and lakes
Agriculture policy
-Governments have long used policy to encourage agricultural production -Recent policy has tried to lessen the environmental impacts of external costs -Market forces should discourage practices that degrade the land, but degradation occurs slowly -Farmers and ranchers can not go without profits in the short term, but subsidies might also lead to overproduction of food, thus creating undervalued produce
Overgrazing
-Grazing animals on rangeland can be sustainable if the total number of grazing animals is kept below the rangeland's carrying capacity -Overgrazing = occurs when too many animals eat too much of the plant cover -> Impedes plant regrowth -Soil is exposed, allowing erosion, less regrowth, and positive feedback of more erosion -Non-native invasive species invade -> outcompete native vegetation, less palatable to livestock so not eaten -Trampling compacts the soil, preventing water infiltration -U.S. government subsidies increase harm (ranchers pay little to graze their animals on public land, few incentives to protect rangeland -> tragedy of the commons)
No-till farming
-Leaving crop residue atop the fields -Benefits the soil because repeated plowing and planting damage soil -Saves time and money
What are some sustainable approaches to irrigation?
-Matching crops to the climate can reduce or eliminate the need for irrigation (ex. Growing cotton in dry climates requires extensive irrigation while wheat does not) -In conventional irrigation, as little as 43% of the water applied is used by the crops -Drip irrigation targets water directly to plants, and plants use as much as 90% of the water
6) Source of generic plasmids for genetically modified organisms
A) Escherichia coli Section: 10.4, 10.6 Bloom's Taxonomy: Knowledge/Comprehension
2) Explain the statement "the lower down in the food chain we eat, the greater percentage of solar energy we put to use, and the more people Earth can support" in terms of trophic levels and pyramids of energy.
Answer: Meat is farther from the sun in the food chain than plant material. Consuming meat decreases the amount of usable energy that is obtained directly from the sun because animals must first consume plants before they are eaten by humans. Every time energy moves from one trophic level to the next, as much as 90% of the useful energy present in the lower trophic level is lost. This is because the second law of energy states that entropy increases as one goes from one level to the next and energy is lost as heat or light at each transfer. For this reason, people who rely heavily on meat as a source of food energy are less energy efficient than ones that rely on fewer animal products or a vegetarian diet. The biomass pyramid echoes this, as each trophic level contains less biomass (energy) than the lower level. Section: 10.2 Bloom's Taxonomy: Application/Analysis
6) What are the dangers associated with pesticide use? How can biocontrol and use of crops with high genetic diversity help to decrease the amount of pesticides used?
Answer: Pesticides are toxins that are general biocides that kill many nontarget useful species, such as pollinators and predators, and also can harm humans. Pesticide use has increased to lower crop loss due to pests and increase yield. Increased use results in resistance developing in pest populations. When this occurs, the type of pesticide used has to be altered so that pests can be controlled. Increasing the toxicity of pesticides is often the solution. Biological control can decrease pest density by introducing enemies of the pests to the field. This decreases pest numbers without chemicals. Increasing the genetic diversity of the crop can also decrease pest numbers because pests may not be able to consume all genetic varieties in the crop. Different species also "host" predators of pests and balance nutrient use. This will result in higher yields through healthier plants and reduction of pest populations. Section: 10.4 Bloom's Taxonomy: Knowledge/Comprehension
1) What are the arguments for and against genetically modified crops? Discuss the scientific,economic, and political issues.
Answer: Proponents of GM crops stress continuity with the agricultural past, arguing that there is little reason to expect that today's GM food is any less safe than the selectively bred food of the past. They also argue that conferring pest resistance to crops can decrease use of chemical pesticides. Critics point out that the new techniques differ from traditional breeding techniques because they mix species, create species in the lab, not the field, and deal with novel gene combinations not possible in nature. They worry about allergic reactions in people and the "spread" of inserted genes into the soil and other organisms in the ecosystem. There is also the question of maintaining the genetic diversity and integrity of the many varieties of indigenous crops such as corn. Many of these varieties have been cultivated for centuries by the indigenous farmers of Mexico and many other nations. Corn is wind pollinated, and patented GM corn has been forming transgenic hybrids with a variety of indigenous strains. Unfortunately, there is little to prevent many GM crops from spreading to non-GM crops in adjacent fields. Controversy has arisen as the corporate agribusiness developers of GM crops have been suing farmers for patent infringement because of this unintentional and often unrecognized contamination. Since organic foods cannot contain GM crop genes, the issue of contamination by nearby GM crops is of particular concern to organic farmers. The political debate involves labeling and an individual's right to know what is in the food they consume. Industry has a large financial stake in seeing the continued use of GM foods. Critics argue that we should adopt the precautionary principle with GM foods. Section: 10.6 Bloom's Taxonomy: Knowledge/Comprehension
8) What is the basic concept of sustainable agriculture?
Answer: Sustainable agriculture is agriculture that does not deplete soils faster than they form and does not destroy the biodiversity of the area. Sustainable farming and ranching do not reduce the amount of healthy soil, clean water, genetic diversity of crop plants and animals, such that agriculture can be practiced in the same way in the same place far into the future. Maintaining as much ecological biodiversity as possible in the agro-ecosystem is essential to long-term crop and livestock production. After all, our concept of sustainability is based on the functioning of intact ecosystems, and agro-ecosystems are modified ecosystems which are governed by the same rules of stability and interdependence as their natural counterparts. Section: 10.1 Bloom's Taxonomy: Knowledge/Comprehension
5) What was the Green Revolution, and what impact did it have on developing countries? Discuss the impact of the Green Revolution on the environment.
Answer: The need for higher quantity and better quality of food for the growing human population led in the mid- and late 20th century to the Green Revolution, wherein scientists in the developed world created methods and technology to increase crop output per unit area of existing cultivated land. In developing countries, this greatly increased agricultural production. The Green Revolution has enabled India to stop importing grain and to maintain extra grain reserves as a buffer against food shortages. But it depends heavily upon chemical pesticides and fertilizers, which can be expensive and lead to pesticide resistance. Environmentally, in the short term, this was positive because it decreased the need for new areas for cultivation and reduced rates of deforestation. Unfortunately, it also increased the use of water, chemical fertilizers, pesticides, and fossil fuels, increasing pollution, salinization, desertification, and the chance of crops developing pesticide resistance and thus may not be sustainable. Section: 10.1 Bloom's Taxonomy: Application/Analysis
4) Describe the use of biological control for battling pests.
Answer: This strategy uses predators, pathogens, and parasitoids of crop pests rather than chemicals to control pest densities. An organism that eats a crop pest is released into a crop; it kills the crop pest, decreasing the density of the crop pest without chemicals. The fact that many biocontrol agents are functioning parts of the ecosystem's food web greatly reduces the chances of pests becoming resistant to a predator or disease vector. It goes without saying that biological control of this type precludes using chemical sprays at the same time. Section: 10.4 Bloom's Taxonomy: Knowledge/Comprehension
Is it easier to prevent or correct salinization and waterlogging?
It is easier and cheaper to prevent salinization than to fix it -Do not plant water-guzzling crops in sensitive areas -Irrigate with low-salt water -Irrigate efficiently and only as much as needed Fixing requires flushing soils with large amounts of water
3) Why is variety in crop plants important for "food security"? How is this threatened by GM food crops? What is the U.S. position on GM products? How does this differ from the position of other countries?
Answer: Varieties contain genes that, through conventional breeding, might confer resistance to disease, pests, inbreeding, and other pressures that challenge modern agriculture. Monocultures of industrial agriculture place all our eggs in one basket, so that any single catastrophe could potentially wipe out multiple crops. Wild relatives contain genetic diversity that may have ready- made solutions to unforeseen problems. The U.S. position is that GM foods are an acceptable food crop. Many nations refuse to purchase or accept food or seed crops that are GM. The European Union has been extremely outspoken against the use or trade of GM foods. Section: 10.1, 10.6 Bloom's Taxonomy: Application/Analysis
3) A successful case of biological control, introduced from Argentina to Australia in the 1920s to control invasive prickly pear cactus
C) Cactoblastis cactorum Section: 10.4, 10.6 Bloom's Taxonomy: Knowledge/Comprehension
5) Honeybees are vanishing at an alarming rate because of it
J) colony collapse disorder Section: 10.4, 10.6 Bloom's Taxonomy: Knowledge/Comprehension
Cover crops
Crops planted to hold soil in place between the times that main food crops are growing
Soil texture
Determined by the size of particles -From smallest to largest: clay, silt, sand -Loam: soil with an even mixture of the three -Affects how easily air and water travel through the soil -Influences how easy soil is to cultivate -Soil with lower permeability (clay) is better for retaining water
History of agriculture (arose 10,000 years ago)
Different cultures independently invented agriculture Evidence for the earliest plant and animal domestication is from the "Fertile Crescent" of the Middle East Agriculture rose independently in at least China, Africa, and the Americas Raising crops was a positive feedback cycle -Harvesting the crops required people to be sedentary -Being sedentary encouraged the planting of more crops and production of more food -More crops allowed larger populations -Larger populations required planting more crops
4) Introduced for control of agricultural pests in Hawaii
G) wasps Section: 10.4, 10.6 Bloom's Taxonomy: Knowledge/Comprehension
How do some policies worsen land degradation?
Governments spend billions on farm subsides that may be unsustainable -Some subsidies support growing water-intensive crops in desert regions -Some encourage use of easily degraded land -Proponents argue that uncertainty of crop success justifies subsidies Grazing on federally owned land costs $1.35 per animal unit per month -Low cost encourages overgrazing -Ranchers are now teaming up with environmental activists to prevent loss of rangeland from development
2) Can protect crops from insect pest-related losses when applied periodically
H) Bacillus thuringiensis Section: 10.4, 10.6 Bloom's Taxonomy: Knowledge/Comprehension
Main problem with African soils?
Serious depletion of nutrients in the soil -Population growth has made it worse -Little education on proper use of nutrient supplements -Little money to buy nutrient supplements -Land in sub-Saharan Africa is suffering from severe degradation -Clearing forests for cultivation threatens endangered wildlife and forests
Soil
a complex plant-supporting system -Consists of disintegrated rock, organic matter, water, gases, nutrients, and microorganisms -It is a renewable resource that can be depleted
Soil degradation
a decline in soil quality and productivity -Primarily from deforestation, cropland agriculture, overgrazing -Over the past 50 years, soil degradation has reduced potential food crop production by 13%
Soil pH
affects a soil's ability to support plant growth -Soils that are too acidic or basic can kill plants -pH influences the availability of nutrients for plants
Sustainable agriculture
agriculture we can practice in the same way and same place far into the future
Traditional agriculture and its features
biologically powered form of agriculture that uses human and animal muscle power -hand tools, simple machines -subsistence agriculture: form of agriculture in which families produce only enough food for themselves -polyculture: different crops are planted in one field market economies allowed farmers to sell their product -as demand increased, increased use of irrigation and fertilizer
Intercropping
planting different crops in alternating bands or mixed arrangements -Increases ground cover, preventing erosion -Decreases pests and disease -Replenishes soil
Contour farming
plowing furrows sideways across a hillside perpendicular to its slope -Sides of furrows trap water and prevent erosion
Cation exchange
process that allows plants to gain nutrients -Negatively charged soils hold cations (positively charged ions) of calcium, magnesium, and potassium -Roots donate hydrogen to soil in exchange for these nutrients Cation exchange capacity: a soil's ability to hold cations -Cations that don't leach are more available to plants -A useful measure of soil fertility -Greatest in fine textured or richly organic soils -Decreases with lower pH (so, basic soils have a better cation exchange capacity)
Leaching
process whereby dissolved particles move down through horizons and may end up in drinking water -Some materials in drinking water are hazardous
Weathering
processes that break large rock particles down into smaller ones -Physical (mechanical) = wind and rain; no chemical changes in the parent material -Chemical = parent material is chemically changed -Biological = organisms produce soil through physical or chemical means
