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2 of 2 people found the following review helpful:
5.0 out of 5 stars
This book tells us why food prices will soon increase, 13 Jul 2004
The expansion of irrigation world wide has made a major contribution to increased food production, but for many years the World Watch Institute and the Earth Policy Institute have called attention to the danger of falling water tables and rivers that no longer reach the sea. Although China increased grain production from 90m tons in 1950 to 392 million tons in 1998, this was achieved at the price of rapidly falling water tables with the result that consumption exceeded production in four of the last five years; very soon China will be importing 30 - 50 million tons of grain annually, putting pressure on world grain prices. As wheat requires 1000 tons of water to produce one ton of wheat, the key challenges are: "how can we meet growing human needs for irrigation water without destroying the health of rivers, lakes and other aquatic systems? How can we grow enough food in a sustainable manner?" History tells us that most irrigation-based civilizations fail. The question we must address is "Will our civilization be different?" Settled agriculture started 10,000 years ago in Mesopotamia but around 4,000 BC enterprising Sumerian farmers in the Fertile Crescent - present day Iraq - diverted water from the Euphrates to prevent crops withering before harvest. Irrigation allowed farmers to grow an extra crop and produce surpluses leading to an expanding population and a flourishing civilization but also bringing soil degradation from salt left by evaporation. By the 16th century the Fertile Crescent, was little more than a salty wasteland. 20% of the irrigated land today suffers from salt build up; land lost offsets increased productivity from expanding irrigation. The solution is to use just the amount of water required during the growing season and just enough to leach away salts in the root zone and then to reuse drainage water for crops with a higher salt tolerance such as cotton or tomatoes for canning or paste. The rise and fall of civilizations closely follows the success and ultimate failure of irrigation. In 1800, global irrigated area was about the size of Austria, while today it is 30 times larger, provides 40% of our food, and is the foundation for feeding 70 million new mouths each year. However, our present day base for food production is highly vulnerable as groundwater is over-pumped and salinization spreads. Increasing land productivity is our main hope at a time when water scarcity and water misuse are the biggest threats to global food production. Food prices are at historically low levels making it difficult to justify new investments in irrigation systems. Many important food-producing regions are sustained by the hydrological equivalent of deficit financing. While water shortages are the main problem, they are compounded by global warming bringing a changing climate, shifting rainfall patterns, and more frequent hurricanes and monsoons. In addition low-lying agricultural land is lost as sea levels rise from thermal expansion of the oceans and melting glaciers and ice caps. Increasing land productivity means extending irrigation to the smallest and poorest farmers, particularly in South Asia and sub-Sahara Africa. Irrigation will provide the bulk of the additional food needed in the decades ahead, but there is a shift of water away from agriculture to satisfy rapidly growing urban and industrial demands. We have to grow more food with less water; more crop per drop is the agricultural frontier of the 21st century. "There is no obvious, off-the-shelf package available to raise water productivity. This new challenge will require a more diverse and creative mix of strategies that together make agriculture more information-intensive and less resource intensive. - in most cases, by substituting technology and better management for water. But the technologies and strategies described in this chapter inspire hope that we can achieve the doubling of water productivity needed to satisfy the food, water, and environmental needs of the next several decades - if we choose." Adoption of drip and other microirrigation techniques cut water use and increase crop yields but only 1% of the world's irrigated area uses these methods. If combined with other methods productivity can be greatly improved. "Wuertz pioneered a farming system that combines drip irrigation with minimum tillage of the soil. He buried drip tubing 8-10 inches deep in every crop row, and then practiced multiple cropping of vegetables and field crops (including cotton) along with minimum tillage, leaving the drip irrigation system in place. Studies of Wuertz's low-till drip methods by the University of Arizona showed that the system was able to cut water and energy use by about half and field labor by nearly 60% while increasing lint yield from cotton crops by 13%." Improved management practices can help farmers reduce water demands while maintaining or increasing crop yields. Weather monitoring and satellite technologies help farmers know when crops need irrigation; pricing water more effectively provides an incentive to farmers to use water more efficiently; improving the ability of crops themselves to use water more efficiently; improving the harvest index to get more edible crop from the same amount of water; breeding or bioengineering plants that photosynthesize in a more water-efficient manner; reuse of municipal waste water for irrigation - these are all part of the solution. Much of the world's grain goes to feed livestock but pork requires twice as much grain per kilo as chicken or farmed fish. Many farmers who are too poor to tap the water a short distance below the surface, a flaw which needs to be remedied by providing them access to affordable irrigation. Globally the grain harvest is enough but 15% of the world's population cannot afford grain even at today's historically low prices. Very soon food prices will rise, the housewife will complain at the supermarket, and we will see people starving in poor countries. Then people will ask "What went wrong?" The answers are to be found in this book that should be required reading for everyone.
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