Agricultural Land and Water

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Agricultural Land and Water

• Text extracted from
• The World Food Problem
• Leathers Foster, 2004

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Agricultural Land Use
Source NASA
http//lcluc.umd.edu/images/Science_Themes/Foley1-
large.jpg
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Land Availability

• Ag land has increased slowly
• 2.8 1960s
• 2.3 1970s
• 3.7 1980s
• 2.1 1990s
• Most increases in pasture land

Grazing cattle, Brazil
http//www.ypte.org.uk/docs/factsheets/env_facts/e
nv_images/brazil_cattle.jpg
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Land with Crop Potential

• 2.57 billion hectares of land with crop potential
• Excluding china
• Only using lt 1 billion
• Problems with most unused potential land
• Hilly
• Poor soil
• Poor drainage
• Could increase ag land
• 30

China
http//www.agapetea.com/store/images/common/about_
blacktea3.jpg
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Potential arable land
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Agricultural Intensity
HANPP Human Appropriation of Net Primary
Production
http//www.eoearth.org/upload/thumb/4/45/HANPP_Fig
ure_3.jpg/625px-HANPP_Figure_3.jpg
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Land lost to Ag production

• Urban expansion
• Small effect worldwide
• Global warming may flood coastal areas
• Soil degradation
• 1/3 cropland worldwide abandoned due to erosion

http//upload.wikimedia.org/wikipedia/commons/thum
b/7/7b/Erosion.jpg/397px-Erosion.jpg
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Irrigation

• World Water Use
• Agriculture 69
• Domestic 8
• Industry 23
• Irrigated crops provide 40 of food worldwide
• Yields with irrigation increase 2-3X

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Irrigated land
http//upload.wikimedia.org/wikipedia/commons/4/4a
/Irrigated_land_world_map.png
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Water withdrawals for irrigation
http//news.bbc.co.uk/nol/shared/spl/hi/pop_ups/04
/sci_nat_feeding_the_world/img/3.jpg
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Sandra Postel

• Water use tripled between 1950 and 1990
• as world population soared by some 2.7 billion
• Worldwide demand for water cannot triple again
• without causing severe shortages for
• crop irrigation,
• industrial use,
• basic household needs and
• critical life-supporting ecosystems

http//www.hipco-ne.com/images/gated.gif
http//www.globalwaterpolicy.org/images/sandrapost
el1_19.jpg
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Conserving Ag water

• Water harvesting
• Collecting and saving runoff
• Drip irrigation
• Drought tolerant varieties

Drip irrigation
http//static.howstuffworks.com/gif/irrigation-dri
p.jpg
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Colorado River

• River is drained dry
• before it reaches the ocean
• Heavy irrigation use
• Colorado
• Arizona
• California
• Mexico
• City water supply
• Las Vegas
• Phoenix
• Tucson

California irrigation from the Colorado River
http//aquafornia.com/wordpress/wp-content/uploads
/2008/02/irrigation-_2-by-bor-pfs.jpg
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Irrigation in China

• Yellow river used for irrigation
• River ran dry in 1972
• For 15 days
• Since 1986 runs dry every year
• In 1997, dry for 227 days

Yellow River
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India River Interlink Plan

• 200 billion plan
• to bring water to south India
• Will link 36 rivers with canals
• Completed in 2016
• Potential benefits
• Reduce flooding
• Hydroelectric power
• Irrigation

http//www.ben-center.org/riverMaps/RiverLinkingMa
inMap.jpg
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Vandana Shiva

• Industrial ag requires 5x water of indigenous ag
• wheat and rice
• Pumping groundwater not the solution
• Aquifers depleted
• Big dams not the solution
• benefit cities, investors
• Ecologically destructive
• Displaces poor farmers
• Many small dams better

Small dam, India
http//farm4.static.flickr.com/3018/2397775485_c4f
ce43d8d_m.jpg
http//www.netradiomeeting.it/public/foto/SHIVA_VA
NDANA.jpg

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Aswan Dam, Egypt

• Benefits
• Controls flooding of Nile River
• Hydroelectric power
• Problems
• Fertile silt not deposited
• Farmers must use fertilizer
• Schistosomiasis increase
• Nile delta receding
• Increased salinity

http//www.2travel2egypt.com/sightseeing/images/as
wandam.jpg