1. Chapter 8: Soil
Part 3

2. Erosion
Erosion: the process of soil and humus particles being picked up and ___________ away by water and wind
Occurs any time soil is bared and ___________
Soil removal may be _______ and gradual (e.g., by wind) or ___________ (e.g., gullies formed by a single storm)
_____________ cover prevents erosion from water
Reducing the ____________ of raindrops
Allowing slow _____________
Grass is excellent for erosion ____________
Vegetation also slows wind _______________

3. Splash, sheet, and gully erosion
__________ erosion: begins the process of erosion
Raindrops _______ up the clumpy structure of topsoil
Dislodged particles wash ________ other aggregates
____________ infiltration and aeration
_________ erosion: the result of decreased infiltration
More water ____ ____, carrying away fine particles
Gully erosion: water __________ into rivulets and streams
Water’s greater volume, velocity, energy remove soil
Once started, erosion can turn into a vicious cycle
Less vegetation exposes soil to more erosion

4. Desert pavement
Another devastating feature of wind and water erosion: ________________removal of soil particles
______ humus and clay are the first to be carried away
Rocks, stones, coarse sand ____________
The remaining soil becomes _____________
Deserts are sandy because ________ removes fine material
Desert pavement: occurs in some deserts
Removal of fine material leaves a thin surface ______ of stones and gravel
This protective layer is easily _____________ (e.g., by vehicles)

5. Formation of desert pavement

6. Cryptogamic crusts ____________ erosion can change soil composition
Rainfall clogs soil
Soil ____________ when it dries
Cryptograms (algae, ____________, mosses) grow
Growth of these __________ causes a cryptogamic crust
It ________________s soil
It adds nutrients through nitrogen ___________
It can __________ infiltration and seed germination
These crusts are easily broken up by __________, etc.
Loosened soil is subject to wind and water erosion

7. Drylands and desertification
Clay and humus are the most _______ parts of soil
For nutrient- and water-holding capacity
Their removal results in nutrients being removed
Regions with _______ rainfall or long dry seasons support grasses, scrub trees, and crops only if soils have good water- and nutrient-_________ capacity
Erosion causes these areas to become deserts
Desertification: a __________ reduction in the productivity of arid, semiarid, and seasonally dry areas (drylands)
Does not mean advancing deserts

8. Drylands Desertification is a process of land ___________
Due to droughts, overgrazing, erosion, deforestation, _____________________
It is extremely serious because it is ____________
Dryland ecosystems cover 41% of Earth’s surface
They are defined by ____________, not temperature
They receive minimal rainfall
Droughts are __________ —they can last for years
Rainfall causes vegetation to ________ so drylands are not desertified

9. Drylands in danger 10–20% of drylands suffer some form of degradation
Inhabited by some of the world’s _____________
The UN Convention to Combat Desertification (______________)
Addresses funding projects to _______ degradation
“_____________” programs so people can help themselves
Gathering and dissemination of ___________ knowledge
TerrAfrica: UNCCD alliance to coordinate efforts to arrest degradation and promote sustainable management
__________ pose the greatest threat to dryland ecosystems

10. Causes of erosion: overcultivation
Plowing to grow crops ___________ soil to wind and water erosion
Soil remains _____ before planting and after harvest
Plowing causes ____________ erosion
Destroying soil’s aggregate ___________
Decreasing aeration and infiltration
Tractors _____________ soil
Reducing aeration and infiltration
Increasing ____________ water loss and humus oxidation
____________ cash crops with hay and clover is sustainable

11. No-till planting
__________ agriculture: a technique allowing continuous cropping while minimizing erosion
Routinely practiced in the ________.
After spraying a field with __________ to kill weeds
A planting apparatus cuts a _________ through the mulch
Drops ____________ and fertilizer
Closes the furrow
The waste from the previous crop becomes ______
So the soil is never ________________
Low-till farming uses _______ pass (not 6–12) over a field

12. Inorganic fertilizer Can provide optimal amounts of nutrients ________
But it lacks ________ matter to support organisms and build soil structure
It can keep nutrient content high under _________ cultivation (two or more cash crops/year)
But ______________ and soil degradation proceed
Additional fertilizer _____________ into waterways
Chemical fertilizers have a valuable ___________ in agriculture
Organic fertilizers may not have enough __________
Growers must use each fertilizer as necessary

13. Reducing soil erosion
___________ __________cropping: plowing and cultivating at right angles to contour slopes
____________: protective belts of trees and shrubs planted along plowed fields
The U.S. Natural Resource Conservation Service (NRCS)
Established in response to the _________ _________
Regional offices provide information to farmers and others regarding soil and water conservation _______
U.S. soil erosion has decreased through conservation
Windbreaks, grassed waterways, ___________ to filter runoff

14. Overgrazing
Livestock __________ on grasslands and cleared forest slopes
65% of drylands are grasslands
Land is often overgrazed
_____________ land is eroded and degraded
In the 1800s American buffalo (bison) were slaughtered
Rangelands stocked with ________ were overgrazed
Leading to erosion and growth of ___________ plants
U.S. western rangelands produce less than _____of the forage they produced before commercial grazing
Yet 20% of rangelands remain ______________

15. Degraded rangelands
The National Public Lands Grazing Campaign documents ________ effects of livestock grazing
Competition of livestock with _____ animals for food
One-third of ____________ species are in danger due to cattle-raising practices (predator control, fire suppression)
Wooded zones along streams are __________ and polluted
_________ streams make fish species the fastest-disappearing wildlife group
Desertification impacts 85% of North America’s drylands
The most widespread cause is livestock _________

16. Public lands Overgrazing occurs because rangelands are public lands
___________of the ___________: the incentive is for all to keep grazing, even though the range is being overgrazed
The U.S. Bureau of Land Management (____) and Forest Service leases grazing rights on 2 million km2 of land
Federal land is owned by ______________
Animal unit = one cow-calf pair or _______ sheep
The grazing fee ($1.35/animal unit/month) is ______ what would be paid on private land

17. Why are rangelands overgrazed?
The 1934 Taylor Grazing Act prohibits reducing grazing levels or keeps grazing fees below ______ level
The U.S. government lost ______ million in 2004
$500 million more was lost in ecological ______ (to watersheds, streams, wildlife, endangered species)
When Congress and the BLM try to raise fees, western congressmen threaten to cut the BLM ___________

18. Irrigation Irrigation: supplying water to croplands _________
Dramatically increases ______________
Is a ___________ contributor to land degradation
Flood irrigation: river water flows into canals to ______________ fields
Center-pivot irrigation: water is pumped from a well into a giant pivoting _______________
The U.S. Bureau of Reclamation is involved with supplying irrigation water to the western ________
Irrigating 4 million hectares (10 million acres)
Worldwide irrigation is huge and is still _________

19. Salinization
Salinization: the accumulation of _______ in and on the soil
Suppresses plant growth
Even the ________ irrigation water has some salt
Watering dryland soils ________ minerals in the soil
____________ or transpiration leaves salts behind
Salinization is considered a form of ____________
____ million hectares (3.7 million acres) are lost each year to salinization and waterlogging
160,000 hectares (___________ acres) in California are unproductive, costing $30 million/year

20. Salinization can be avoided or reversed
Enough water must be used to ________ salts downward
Insufficient _________ results in waterlogged soils
Installing drainage pipes is ____________
Kesterson National Wildlife Refuge received drainage from ____________-enriched soils
___________ birds, fish, insects, and plants
It was declared a ___________ waste dump
It has been drained and capped with __________
Over 14 other U.S. locations have toxic irrigation water
The “Kesterson Effect”

21. Soil conservation
Healthy soils are essential for agricultural production
_______ activities (overcultivation, overgrazing, deforestation) cause erosion
Sustainability means doing all we can to reduce erosion
Soil conservation must be practiced at two levels
________ landholders can best preserve soil through traditional knowledge and practices
_________ policies can lead to conservation or disaster

22. Helping individual landholders
Individual landholders, farmers, and herders hold the key to sustainable soil stewardship
They must be convinced that conservation will work
That it is _______ and will help them in the ____ ___
Small, realistic steps must be taken
______________, advice, and encouragement
Sustainable Agriculture and Rural Development Initiative (SARD) coordinates efforts to reach small farmers
_____________organize and adopt sustainable practices
These practices can be used in other similar situations

23. The Keita Project Niger is one of the ________ countries in the world
Part is in the Sahel, a _____________ grassland
In 1982 the Italian government started an ______________ project in the Keita district, which has 230,000 people
_______ were built to catch summer rains
18 million trees were planted
Rock dams stopped _______ erosion
Local people (especially __________) worked
The Keita district is now a flourishing place for crops
Desertification has been halted

24. Land in the Keita district of Niger

25. Two paradigms Desertification is happening in many areas
Leading to permanent damage, poverty, and misery
Human factors: population growth, immigration, _______ land tenure, cash crops
Erosion from overgrazing and overcultivation is made worse by drought and __________ change
Desertification is not inevitable: another option is to recognize degradation and take corrective measures
Better management, soil and water conservation, diversifying income to relieve pressure on the land

26. Public policy and soils
Original U.S. farm policy: increasing __________
This goal was achieved
The federal government supports agriculture through ___________________
Farm policy emphasizes ___________ and farm commodities
Farmers are ____________ price levels for grains, cotton, sugar, peanuts, dairy products, soybeans, etc.
Subsidies cost taxpayers____ billion in 2009
Crop ___________ and loans added $10 billion more
Subsidies occurred in spite of __________ income

27. Subsidies hurt the environment
They encourage excessive use of pesticides and _______________
They reduce crop _____________ by locking farmers into annual crop support subsidies
They encourage _______________ drawdown
For irrigation
Subsidies __________ objectives of soil conservation

28. Goals of sustainable agriculture
Maintain productive topsoil
Keep food safe and wholesome
Reduce chemical fertilizers and pesticides
Keep farms economically viable
Sustainable options mimic past practices
Contouring, crop rotation, terracing, little or no chemicals
The U.S. Sustainable Agriculture Research and Education program (SARE) (1988)
Provides $5–12 million/year for building and disseminating knowledge about sustainable agriculture

29. Farm legislation
Federal Agricultural Improvement and Reform Act (FAIR) (1996) _______ subsidies and controls
Farmers had greater ________ over what to plant
Declining prices prompted farm ___ packages, which maintained subsidies and controls
2002 Farm Security and Rural Investment Act subsidized farm products and kept price supports and farm income
The Food, Conservation and Energy Act of 2008 kept _____ subsidies and encouraged farmers to _______ grasslands
But it does have programs to _________ soil and wetlands

30. Conservation programs
The Conservation Reserve Program (CRP; 1985)
Farmers are paid $125/hectare ($50/acre) per year
Highly erodible land is put into forest or grass
In 2008, 14 million hectares (34.7 million acres) were enrolled, saving 454 million tons of topsoil from erosion/year
The 2009 acreage was reduced to 32 million acres
Conservation activities now receive $5 billion/year
Wildlife Habitat Incentives Program (WHIP)
Environmental Quality Incentives Program (EQIP)

31. Other farmland conservation programs
The 2002 Conservation Security Program (CSP)
Encourages stewardship of farms, forests, watersheds
Renamed the Conservation Stewardship Program in the 2008 farm bill
$1 billion to enroll 12 million acres of farmland
Farmers and ranchers should have incentives to protect soil
Productivity would increase
The most significant obstacle to soil conservation
A lack of knowledge about what conservation can do
Particularly in developing countries

32. Solutions to overgrazing
Better management could ________ rangelands
Benefiting wildlife and ________ production
Conservation Stewardship Program (NRCS)
Provides ________ and support to land-owning ranchers to burn woody plants, reseed land, rotate cattle
The government could buy up some of the 26,000 permits
___________ rangelands
Generously _______ ranchers for their permits
Use the land for wildlife, recreation, watershed _____________

33. Deforestation
Porous, _________-rich forest soil efficiently holds and recycles nutrients
Also absorbs and ________ water
Converting a forested hillside to grassland doubles the amount of ________ and increases nutrient leaching
When _________ are cut and soils are left exposed
Topsoil becomes saturated with water and _______ off the slope
___________ continues to erode

34. Forests are cut at alarming rates
13 million hectares (32 million acres) are cut per year
Mostly in ____________ countries
Cutting ___________ rain forests causes acute problems
Heavy rains have ___________ soils of minerals
Parent material is already maximally weathered
So tropical soils (__________) lack nutrients
Clearing rain forests washes away the thin layer of _____________
Leaving only the nutrient-poor subsoil
Very _________ for agriculture

35. The other end of the erosion problem
Water that does not infiltrate enters streams and ____________
Causing __________________
Sediment: _________soil carried into streams and rivers
_______ channels, intensifies floods, fills reservoirs
_______ fish and coral reefs
Damages streams, rivers, bays, ___________
Excess sediments and nutrients from erosion are the __________ pollution problem in many areas
Groundwater is _____________
Rainfall runs off and does not refill soil or ground water

36. Irrigation Irrigation: supplying water to croplands _________
Dramatically increases ______________
Is a ___________ contributor to land degradation
Flood irrigation: river water flows into canals to ______________ fields
Center-pivot irrigation: water is pumped from a well into a giant pivoting _______________
The U.S. Bureau of Reclamation is involved with supplying irrigation water to the western ________
Irrigating 4 million hectares (10 million acres)
Worldwide irrigation is huge and is still _________