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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