Education for Sustainable Living, Environmental Respect, and Celebrating the Quality of Life.

Water and Agriculture

        In the book A Pillar of Sand, Sandra Postel (1999) notes that the path that food production takes will depend on water.  The German scientist Justus von Liebig was noted for stating that plant growth was limited by the most limiting nutrient, much as a barrel with uneven staves.  The most common yield limiting element in crop production today is water.  Even in water-rich states like Maine, we often find agricultural production limited by water.  As the graph below indicates, we appear to be reaching a global grain production plateau.  We derive nearly 40% of our food from irrigated land, and one out of five acres is deteriorated now by salinity.    

Agricultural demand for irrigation water

        Our capacity for agriculture to keep pact with population food demand will ultimately rely on our capacity to breed plants to more efficiently utilize water, and to improve irrigation methods to double productivity.  If we do not get twice the yield for every liter pumped from aquifer storage or surface waters, our capacity for food production will not keep pace with population growth and need.  Global water resources are being diminished at an alarming rate, and irrigation demand is a key factor in many countries as seen in the UNEP graphics below.   

The dominance of agricultural water use as the major water consumer in the world can be seen in this UNEP graphic.

As can be seen in the graphic below, withdrawl and consumption of water on a world-wide basis is highest in Asia.  Given the high population density, this is not surprising.  The question remains can Asia continue its level of growth and not be limited by the total availability of water.  Ecological disasters have already occurred in Central Asia, and without better planning, they could happen again.  

Putting knowledge to work with the people of Maine

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Last Modified: 09/13/2006
These pages are currently being maintained from the
Water Quality Office, University of Maine Cooperative Extension.
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