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