also be effective in crops like rice, but may be too expensive an investment for widespread use in field crops. The tools do not have to be complex. For example, the PaniPipe project in Bangladesh involves locating short plastic pipes in paddy fields that allow farmers to easily see the water level and optimize their use of irrigation water—avoiding overuse in situations where perfect leveling is not possible. This led to a 46 percent reduction in water used and a large profit increase for the farmers.

image

FIGURE II 2-1 Areas of physical and economic water scarcity.

SOURCE: Bushell 2011; IMWI Report, Insights from the Comprehensive Assessment of Water

Management in Agriculture, 2006, p. 8.

The biggest negative externality of intensive farming is arguably the diffuse contamination of water bodies with run-off from agricultural fields. Intense rainfall events can physically wash soil particles off fields, carrying fertilizer and pesticide residues into ditches and streams. The downstream effects of nitrogen (N) and phosphorus (P) pollution can result in creation of algal blooms, eutrophication and even “dead zones.” Landscape planning can help minimize these effects, using high-resolution GIS to identify high risk areas at a regional, watershed and farm level. Areas of particular risk are those where the principal risk factors are found together (i.e., areas where crops are planted on shallow soils on an impervious base, with a slope greater than 2°. Fields can be identified where run-off risk is highest and effective mitigation measures can be discussed with the farmer (could be enhanced watercourse protection through buffer strips or woodland, use of no-till or cover crop practices, or in some cases not using particular products or growing crops at all). A 10 meter margin can reduce run off by 90 percent (Reichenberger et al., 2007), but in practice these benefits may not always be fully



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement