Agricultural Land and Water Text extracted from The World Food Problem Leathers & Foster, 2004 ttp:// Toward-Undernutrition/dp/

Agricultural Land Use Source: 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

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% China

Potential arable land

Agricultural Intensity HANPP: Human Appropriation of Net Primary Production

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

Irrigation World Water Use: –Agriculture69% –Domestic 8% –Industry23% Irrigated crops provide 40% of food worldwide Yields with irrigation increase 2-3X

Irrigated land

Water withdrawals for irrigation

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

Conserving Ag water Water harvesting –Collecting and saving runoff Drip irrigation Drought tolerant varieties Drip irrigation

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

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

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

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

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