Climate change, water supply limits, and continued population growth have intensified the search for measures to conserve water in irrigated agriculture, the world's largest water user. Policy measures that encourage adoption of water-conserving irrigation technologies are widely believed to make more water available for cities and the environment. However, little integrated analysis has been conducted to test this hypothesis. This article presents results of an integrated basin-scale analysis linking biophysical, hydrologic, agronomic, economic, policy, and institutional dimensions of the Upper Rio Grande Basin of North America. It analyzes a series of water conservation policies for their effect on water used in irrigation and on water conserved. In contrast to widely-held beliefs, our results show that water conservation subsidies are unlikely to reduce water use under conditions that occur in many river basins. Adoption of more efficient irrigation technologies reduces valuable return flows and limits aquifer recharge. Policies aimed at reducing water applications can actually increase water depletions. Achieving real water savings requires designing institutional, technical, and accounting measures that accurately track and economically reward reduced water depletions. Conservation programs that target reduced water diversions or applications provide no guarantee of saving water.

https://www.pnas.org/content/pnas/105/47/18215.full.pdf

Water conservation in irrigation can increase water use

Cost-effective design of agri-environmental payment programs: U.S. experience in theory and practice

This publication presents the results of the latest (2002) inventory of U.S. major land uses, drawing on data from the Census, public land management and conservation agencies, and other sources. The data are synthesized by State to calculate the use of several broad classes and subclasses of agricultural and nonagricultural land over time. The United States has a total land area of nearly 2.3 billion acres. Major uses in 2002 were forest-use land, 651 million acres (28.8 percent); grassland pasture and range land, 587 million acres (25.9 percent); cropland, 442 million acres (19.5 percent); special uses (primarily parks and wildlife areas), 297 million acres (13.1 percent); miscellaneous other uses, 228 million acres (10.1 percent); and urban land, 60 million acres (2.6 percent). National and regional trends in land use are discussed in comparison with earlier major land-use estimates.

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Major Uses of Land in The United States, 2002

Cover crops are well recognized as a tool to reduce NO leaching from agroecosystems. However, their effectiveness varies from site to site and year to year depending on soil, cash and cover crop management, and climate. We conducted a meta-analysis using 238 observations from 28 studies (i) to assess the overall effect of cover crops on NO leaching and subsequent crop yields, and (ii) to examine how soil, cash and cover crop management, and climate impact the effect of non-leguminous cover crops on NO leaching. There is a clear indication that nonleguminous cover crops can substantially reduce NO leaching into freshwater systems, on average by 56%. Nonlegume-legume cover crop mixtures reduced NO leaching as effectively as nonlegumes, but significantly more than legumes. The lack of variance information in most published literature prevents greater insight into the degree to which cover crops can improve water quality. Among the factors investigated, we identified cover crop planting dates, shoot biomass, and precipitation relative to long-term mean precipitation as potential drivers for the observed variability in nonleguminous cover crop effectiveness in reducing NO leaching. We found evidence indicating greater reduction in NO leaching with nonleguminous cover crops on coarse-textured soils and during years of low precipitation (<90% of the long-term normal). Earlier fall planting and greater nonleguminous shoot biomass further reduced NO leaching. Overall, this meta-analysis confirms many prior studies showing that nonleguminous cover crops are an effective way to reduce NO leaching and should be integrated into cropping systems to improve water quality.

Cover Crops Reduce Nitrate Leaching in Agroecosystems:A Global Meta-Analysis.

Agricultural insurance in developed countries originates in named peril products that were originally offered by private companies approximately two hundred years ago, first in Europe and then in the United States. Today, many agricultural insurance products are offered, most of them heavily subsidized by governments. In the context of developed economies, this article examines the evolution of agricultural insurance products, the economics of the demand and supply sides of agricultural insurance markets, and the economic welfare, political economy, and trade relation implications of private and public agricultural insurance in developed countries.

Agricultural Insurance in Developed Countries: Where Have We Been and Where Are We Going?

Environmental quality incentives program

This report provides an item-by-item description and explanation of the new Act, which will guide agricultural programs from 1996-2000. Signed into law in April, the act makes significant changes in long-standing U.S. agricultural policies. Major changes in U.S. commodity programs are included in the Act's Title I, known as the Agricultural Market Transition Act.

Lyle P. Schertz

Papers

Environmental quality incentives program

Provisions of the Federal Agriculture Improvement and Reform Act of 1996

Conservation security program

Federal crop insurance

Country of origin labeling