Environmental Science Name: ______________________________
Food and Agriculture
Goal: The student will distinguish between traditional and modern agricultural techniques, describe fertile soil and describe the need for soil conservation.
Vocabulary:
1.
Arable land
2.
Topsoil
3.
Erosion
4.
Desertification
5.
Compost
6.
Salinization
Chapter 9.2: Crops and Soil
•
Earth has a __________________ amount of arable land (fertile) to grow crops; _____________________ every year (1/5 from 1985 to 2000)
•
___________ million acres of farmland will be covered by houses and industry; 334 million acres will become unusable for farming because _____________________ will be damaged
•
This shortage of _________________________ land threatens our ability to feed the human population
Agriculture: Traditional and Modern
•
Plowing, fertilization, irrigation and pest control began with the earliest _______________________; animals or people pulled plows through the soil (mixes up the nutrients, loosens soil and uproots weeds)
•
_______________________ fertilizers (manure) enriched soil; digging ditches supplied water; weeds were dug up by hand – still used today in many places
•
Large farms in industrialized countries use __________________________________ (to plow and harvest);
______________________________________ fertilizers are used to enrich soil; overhead drips/ sprinkles for irrigations; chemicals kill pests
Fertile Soil: The Living Earth
• Soil that can support the __________________growth of healthy plants is called fertile soil; most root in
____________________________________ (rich in organic matter; loose soil comprised of living organisms, rock particles, water, air and organic matter)
• Most soil forms when _________________ is broken down into smaller and smaller fragments by wind, water and chemical weathering (when minerals in the rock react chemically with substances such as _______________ to form new materials); ___________________________________ changes and moisture cause rock to crack and break apart, making smaller particles where pioneer species can take root and grow; It can take thousands of years to ______________________ a few centimeters of soil
• _______________________ organisms (earthworms, insects and other small animals) play an important role in breaking up the soil; also the decomposers (fungi, bacteria, microorganisms) when they break down
_________________
• One clear way to know if soil is fertile is to look for __________________________________.
• There are _______________________ layers of soil which lie under the topsoil; bottom layer is called the bedrock (solid rock from which soil originally forms)
Soil Erosion: A Global Problem
• Soil that has been formed is being lost to _________________________
• In US, about ½ of the _______________________ has been lost to erosion in the past 200 years; worldwide, 11% of the soil has been __________________________ in the past 45 years
• Soil erosion is ranked as one of the most serious _______________________________ problems we face today
• Some ___________________ techniques today contribute to the erosion (blowing wind and rain washing it away)
• Harvesting removes roots and other ___________________________matter that holds the soil together; clearing forests for lumber; water ___________________________ carries away the soil

Land Degradation
•
Land Degradation happens when human activity or natural processes ________________________ the land so that it can no longer ________________________________ the local ecosystem
•
Loss of topsoil, especially in ________________ areas, is severe; if it deteriorates so much the land becomes desert-like (desertification); worldwide an area the size of Nebraska becomes __________________ every year; this process is causing ______________________ land to disappear
• Ex: In Northern Africa, if the appropriate method of rotating the _______________________ and grazing their animals were observed, the land would adequately ______________________________ the people of that region; however, today, increased ____________________________ of the land and large numbers of grazing animals have left the land barren. Because of the overgrazing, the land can _______________ longer support the plants that held the topsoil in place, resulting in _____________________________ rather than productive farm/grazing land
Soil Conservation
• There are many ways to __________________________ topsoil and reduce erosion; soil usually erodes downhill
• Pay attention to the __________________ of the land when planting, contour plowing (plowing across the slope of the hill), leaving___________________ of vegetation running across the hillside, not farming in an area where it is very hilly; terracing, multiple, small, level fields used on a hillside; often used for wine grapes and coffee
• Change the way farmland is ________________________…ex: no-till farming - rather than plowing under, plant _____________ crops through the remains of the old plants allowing less erosion (reduces soil erosion to
1/10 that of traditional methods), saves time; however, there are disadvantages to this method: _______________
• may become too densely _________________________ over time and therefore, lower crop yields over time.
_________________________ _______________________ ___________________________
Enriching the Soil

____________________________ fertilizers: organic matter such as manure and leaves were added to the soil; as it decomposes, it adds nutrients to the soil and improves the texture of the_________________

________________________ fertilizers that contain nitrogen, phosphorous, and potassium have changed farming methods; without these fertilizers, world ________________production would be less than half of what it is today

Over the past _______ years, use of such fertilizers has rapidly increased; if soil erosion would occur in areas where these fertilizers (inorganic) are being used, waterways will be at risk of being _______________________

A ______________________ method of enhancing soil is to use both organic and inorganic fertilizers by adding
________________________ (partly decomposed organic material) and chemical fertilizers to the soil

Compost can be purchased (composted cow manure) in stores; _____________waste and crop waste can be used
Salinization
•
Salinization is the accumulation of __________________ in the soil; salt is in the soil naturally, but when it is
____________________________ with water from rivers or groundwater, it builds up and makes the land unusable; rainwater contains ___________________ salt than groundwater
•
Major issue in places such as California and Arizona which have _________________ rainfall and have naturally salty soil; soil is salty because the water used for irrigation is saltier than _________________________, when it
_______________________________ it leaves behind the salt; over time it will become too salty to plant
• Ways to slow soil salinization: irrigation canals, water soil heavily prior to planting seeds, __________________ salt tolerant crops or trees to __________________________________ the land (shade trees will reduce evaporation from the soil surface; fallen leaves add organic matter to the soil)
• Total _________________________________________ of the land takes decades

Lesson Reflection:
Using the handout labeled The Structure and Composition of Soil, complete by filling in the characteristics of each layer (page 233).
Assessment:
1.
Explain the differences between traditional and modern farming methods.
2.
Describe the structure and composition of fertile soil.
3.
Explain why the presence of plants helps prevent soil erosion.
Lesson Extension (Technology/Application/Connection to Real World):
Get together with a small group of classmates and plan a short public service announcement for soil conservation. Be sure to touch on different farming methods, land degradation and salinization. What can we do to make a difference?