Agricultural Land and Water
Text extracted fromThe World Food ProblemLeathers & Foster, 2004
ttp://www.amazon.com/World-Food-Problem-Toward-Undernutrition/dp/1588266389
Agricultural Land Use
http://lcluc.umd.edu/images/Science_Themes/Foley1-large.jpgSource: NASA
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/env_images/brazil_cattle.jpg
Land with Crop Potential• 2.57 billion hectares of
land with crop potential– Excluding china
• Only using < 1 billion• Problems with most
unused potential land– Hilly– Poor soil– Poor drainage
• Could increase ag land – 30%
Chinahttp://www.agapetea.com/store/images/common/about_blacktea3.jpg
Potential arable land
Agricultural Intensity
HANPP: Human Appropriation of Net Primary Productionhttp://www.eoearth.org/upload/thumb/4/45/HANPP_Figure_3.jpg/625px-HANPP_Figure_3.jpg
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/thumb/7/7b/Erosion.jpg/397px-Erosion.jpg
Irrigation
• World Water Use:– Agriculture 69%– Domestic 8%– Industry 23%
• Irrigated crops provide 40% of food worldwide
• Yields with irrigation increase 2-3X
Irrigated land
http://upload.wikimedia.org/wikipedia/commons/4/4a/Irrigated_land_world_map.png
Water withdrawals for irrigation
http://news.bbc.co.uk/nol/shared/spl/hi/pop_ups/04/sci_nat_feeding_the_world/img/3.jpg
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/sandrapostel1_19.jpg
Conserving Ag water
• Water harvesting – Collecting and
saving runoff
• Drip irrigation• Drought tolerant
varieties
Drip irrigation
http://static.howstuffworks.com/gif/irrigation-drip.jpg
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
http://aquafornia.com/wordpress/wp-content/uploads/2008/02/irrigation-_2-by-bor-pfs.jpg
California irrigation from the Colorado River
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 daysYellow River
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/RiverLinkingMainMap.jpg
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://www.netradiomeeting.it/public/foto/SHIVA_VANDANA.jpg
http://farm4.static.flickr.com/3018/2397775485_c4fce43d8d_m.jpg
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/aswandam.jpg