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Name ____________________________ Period ______________ Date _________________________
Unit 8: Soil & Agriculture (Notes)
Soil Composition
Soil is made up of:
1) _____________________________________________
2) _____________________________________________
3) _____________________________________________
4) _____________________________________________
5) _____________________________________________
6) _____________________________________________
Soil is composed of ~_____% mineral material, ~_____% organic matter (decomposing organisms & microorganisms) & ~_____% water and air.
One teaspoon of soil can contain ____________ of bacteria and ______________ of fungi, algae and protists!
Soil Formation
• Soil formation is influenced by:
1) __________ - soil forms faster in warm, wet places
2) ____________ - animals burrow and aerate the soil and add organic material
3) ____________ – steeper slopes slow the formation of soil layers
4) _________________ - base geological material
5) ___________ - More time, more soil
Parent Material – base geological material found in a particular area.
Five types of parent material include:
o ________________________
o ________________________
o ________________________
o ________________________
o _________ - continuous solid rock that makes up the crust
Once parent material is exposed to air, there are 3 main processes that lead to soil formation:
1) _____________: process that breaks rock down into smaller particles
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• ____________ – Natural breakup of rock without a chemical change
Ex. Wind, Rain & Heat Expansion
• _____________ – Break down of rocks and parent materials into different materials
Ex. Water & Decomposing Organisms (Carbon Dioxide)
2) _____________: Pick-up, transport, and drop-off of eroded materials from one place to another
*Erosion can be a _________ thing because it allows soil to form in another location
3) _________________: Breakdown of waste, organisms, and organic material into simple molecules
Ex. Deciduous trees drop their leaves to form leaf litter
_________- partially decomposed organic material. A dark, spongy crumbly mass made up of complex organic compounds
Soils with a high humus content hold moisture well and contain nutrients
Soil Horizons
• Soil ___________ are distinct layers of soil.
• A cross-section of soil horizons is a _____________.
• Topsoil (A Horizon) is composed of _________particles mixed with ___________ material (like humus from the O Horizon).
• ___________ (eluviation) – the process whereby solid particles suspended or dissolved in liquid are transported to another location.
* Not all soils contain all six soil horizons
Soil Characteristics
• U.S. soil scientists define 12 major soil groups.
• Soil groups are further classified according to properties such as: _________________________________.
Color
______ soils are normally rich in humus and nutrients and _______ soils are normally poor in humus and nutrients.
Texture
Soil texture is based on particle size
• _______ particles are less than 0.002 millimeters in diameter
• _______ particles are 0.002 to 0.05 millimeters in diameter
• _______ particles are 0.05 to 2 millimeters in diameter
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• Most soils are a mixture of the 3 particles. Soil with a relatively even mixture of all 3 is known as _________.
• How would you describe the texture of a soil that is 40% sand, 40% silt and 20% clay?
• Soil texture influences soil ____________ (how easy it is to plant and harvest from).
• It also dictates how _________ a soil is – size of the spaces between the particles.
• The smaller the particles, the smaller the pores and the more difficult it is for air and water to travel to plants.
• _________ has the smallest particles so it is the least porous.
• _________ has the largest particles so it is the most porous.
• _________ or ________ soils are the best for plant growth
Structure
• _______________ of Soil Particles
Ex. How clumpy is the soil?
pH
• ___________ or ____________
• Plants have a pH tolerance range and will die in soils that are too acidic or alkaline for them
In general, the most productive soil is __________, with a neutral ____, that is _____________, contains ____________ & holds ____________.
Soil Degradation
• ___________________ - The deterioration of the soil characteristics needed for plant growth or ecosystem services
• Human activities can cause 3 main types of soil degradation:
1) _________________
2) _________________
3) _________________
Erosion
• Even though erosion and deposition can help create soil, erosion usually occurs much _________ than soil is formed.
• Caused by __________________ & ___________________
• Humans encourage erosion by:
1) Leaving soil bare after a ___________
2) ______________ rangelands
3) Clearing forests on _____________
4) _______________ forests3
• Crops, trees, and other plant communities _________ soil from erosion.
Farming Practices that Reduce Erosion:
1) ________________: Different crops mixed together so it provides more plant cover
2) _______________: Crops are alternated or a cover crop is planted
3) ______________: Tall plants block wind & prevent wind erosion.
4) Conservation _________: Soil turnover is reduced.
5) ___________: Steep slopes turned into “steps”
6) ___________________: Planting perpendicular to hill’s slope
Ranching Practices
• ___________ is the raising and grazing of livestock.
• When too many animals each too much of the plant cover, slowing regrowth, it is known as _____________.
• Overgrazing causes and worsens many _______ problems.
• Overgrazing on publicly owned land can be an example of ________________________________.
• In response, range managers often encourage _______________ and enforce them on publicly owned land.
Forestry Practices
• Forestry practices, such as ________________, can increase erosion.
• Today, practices that reduce soil erosion, such as _________________ logging are increasingly common.
Desertification
• Loss of more than ______ of soil productivity
• Causes: soil compaction, _________, overgrazing, drought, depletion of _________________or other factors
• _____ and semi-arid lands are the most prone because they get too little _______________ to keep up with growing human population.
• The _____________ was a major desertification event in the 1930s.
• Poor agricultural practices and a massive _________ caused extreme _____________ and led to this event.
Soil Conservation Efforts
• U.S. ___________________ Act (1935): Established the Soil Conservation Service, today called the Natural Resources Conservation Service
• Farmer-Centered Agricultural Resource Management Program (________): A United Nations effort that focuses on resource challenges in developing nations
Soil Pollution
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• Too much, or carelessly timed irrigation can __________ crops or lead to ____________________—a buildup of salts in upper soil horizons.
Ways to prevent salinization:
1) Avoid planting crops that require a lot of water in ____ areas
2) Irrigate with water that is ______ in salt content
3) Irrigate efficiently (________________)
*Another option is to simply plant _______________ crops such as barley
• ___________ - a chemical that kills organisms which compete with crops
• Toxic pesticides can remain in soil for a long time, eventually filtering to _______________.
The Beginnings of Agriculture
• People were ___________________ through most of human history, until agriculture developed about _______ years ago.
• In early agriculture, people began planting seeds from plants they liked most, a form of ____________________.
• Crop cultivation enabled people to settle permanently, often near ________ sources, and raise ___________.
• Agriculture and livestock provided a _________ food supply, which allowed the development of modern ____________.
Traditional Agriculture
Agriculture “powered” by __________________
• Does not require any _________________
• Practiced widely until the ___________________
Industrial Agriculture
• Agriculture that requires the use of ______________
• Involves ___________ farming technology, manufactured ____________, and large-scale ___________
• _______ increased dramatically
• To be efficient, large areas are planted with a single crop in a ______________.
• Advantage:
_________________________________
• Disadvantage:
_______________________________________________________________________________________________
The Green Revolution
• Introduced new _____________, crop _________, and farming practices to the _____________ world in the mid- to late 1900s
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• Came from the desire to have more and better food for the world’s growing ____________
• Norman Borlaug began the revolution by giving Mexico’s farmers a specially bred strain of ____________
* In this case, “Green” means ______________________ not ___________________________
Benefits:
• Increased _____________ and saved millions of people from ___________ in India and Pakistan
• Prevented some _________________ and ______________ by increasing yields on cultivated land
Costs:
• Led to a __________ increase in energy used by agriculture (Between 1900 & 2008)
• Worsened _____________, _____________, desertification, eutrophication, and ______________
Pests and Weed Control
• ______ - an organism that damages something that is valuable to us (like crops)
• _______ - a plant that competes with our plants
Chemical pesticides: ______________________, but can lead to ______________
• When an organism contains a ________ that allows it to survive the pesticide, it will survive and pass that trait onto its _____________
• Over time, the frequency of this gene will __________ in the population and the pesticide will be less ______________
Biological pest control: Controlling pests and weeds with organisms that _____ or _________ them
• Ex. Parasitoid _______ on tomato ___________
• Ex. ___ (Bacillus Thuringiensis) is a bacteria that produces a _________ that kills many pests
Can be a permanent solution, but can harm nontarget organisms
• Ex. The Cactus Moth
• The cactus moth was taken to Australia from Argentina and used to eat the ____________________ which was considered a weed.
• It was successful in Australia but when it was brought to the ____________, it spread to ________ and devastated many of the rare native cacti there.
Integrated pest management: Increasingly popular solution.
• Includes a ______________ of:
• ___________ pest control
• Close monitoring of populations
• Habitat alteration
• _______________
• Reduced soil tillage
• Mechanical pest removal
• __________ pesticides
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• Has worked well in _______
Pollinators• Pollination is the process by which male sex cells of a plant (_______) fertilize female sex cells of a plant
(______).
• Animals which carry the pollen from one flower to the next are called _____________.
• Agriculture (~ _____________) relies on pollinators, such as insects.
• Native and domesticated pollinator populations have __________ due to pesticide use, parasites, and ___________ causes.
• Ex. __________
• In order to conserve pollinators, pesticides should be limited and ______________________ should be used
Food Security
• It is estimated that there will be __________ people on the planet by 2050.
• We are running out of ________ land (land suitable for farming)
• Since 1960, our ability to produce food has grown faster than the human population, but __________ people are currently hungry worldwide.
• ______________ (a shortage of nutrients in the body) & ____________________ (receiving less than 90% of daily caloric needs) are most common in the _____________world.
• For most undernourished people, the reason is ___________
• Kwashiorkor – Too little _________ (bloated belly)
• Marasmus – Overall undernourishment (not enough calories or nutrients)
• Even though this problem is most common the developing world, it is estimated that ______________ Americans are food insecure.
• Agriculture scientists and policymakers are working toward __________________—the guarantee of an adequate food supply for all people at all times.
• Food security depends on:
• Maintaining healthy soil & water
• Protecting _____________ of food sources
• Safe______________ of food
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Genetically Modified Organisms (GMOs)
• One possible way to feed more people is through genetically modified organisms (_______)
• GMOs - Organisms that have had their ______ modified
• Engineered through ______________________________, which means that DNA from multiple organisms is pieced together.
• A desired _______ is taken from one organism and place in another.
• Ex. Rapid growth, pest resistance, & frost tolerance
• Ex. ___________________ (the corn is engineered to make the protein that kills caterpillars and other pests)
• In the United States, 85% of ______ and more than 90% of soybean, ________, and canola crops come from GM strains.
• Worldwide, 70% of soybean crops and 25% of corn crops are GM.
Risks:
• Potential for “_______________” that are resistant to pest-resistant crops
• Contamination of ____________ plants
Ex. GM genes have made their way wild corn and grass
• So far, there is ____________ evidence of harm
Benefits:
• Insect-resistant crops reduce the need for ______________.
• Reduced __________ emission (~6.3 million cars worth).
• More efficient __________________
Unfortunately, at this time, GMOs are doing little to address the issue of world hunger because the traits that are focused on benefit _______________________ and some nations has _____________ that prevent the use of GM crops.
• ______________ is an example of a globally beneficial GM crop
• The rice is engineered to contain ___________ with the hope to prevent a deficiency that can lead to problems such as blindness.
Industrial Food Production: Feedlots
• Feedlots AKA ______________
• Alternative to ______________ in which energy-rich food is delivered to a ________________ group of livestock or poultry
• More than ______ of the world’s pork and poultry comes from feedlots
Benefits: Reduces soil degradation, ______________ and __________ use
Costs:
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1) Requires ________________
2) Has the potential for ________ contamination (with antibiotics & steroids)
3) Animal _________
Industrial Food Production: Aquaculture
• ______________ in a controlled environment
Benefits: Can be sustainable; reduces ___________; reduces fossil fuel use
Costs: More difficult to control spread of ___________; produces a lot of waste; potential for farm-raised animals to escape into ______
Effect on Plant Diversity
• People worry that ____________ will outcompete wild plants and cause them to go extinct
• They worry that if this occurs, _____ pest or disease could wipe out ____ of the plants since they would all be genetically the same.
• ______________ have been started to preserve seeds of diverse plants as an insurance against a global crop collapse
Sustainable Agriculture
• Includes alternatives to __________ agriculture
• Does not deplete ______ faster than it forms
• Does not reduce the amount or quality of soil, ______ , and genetic diversity essential to long-term crop and livestock production
• Agriculture that can be practiced the same way far into the _________.
• ______________ agriculture is sustainable agriculture that does not use synthetic chemicals.
• Organic food purchases increased ________ from 1999 to 2008.
• Although organic farming is still a minority, the market continues to increase today.
Locally Supported Agriculture
• Local, small-scale agriculture reduces the use of fossil fuels and _____________ used for transportation and storage.
• People seem to enjoy purchasing produce for _______ and _________ as opposed to ____________.
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