Agriculture Reference
In-Depth Information
of groundwater in parts of the United States. Contamination is considered criti-
cal to human health at 10 mg/L, which was established by the US Environmental
Protection Agency. The T T-value in the universal soil loss equation (USLE) is an
example of a somewhat more flexible or reversible SMS relative to long-run pro-
ductivity of the soil. One could envision a similar safe standard of sediment inflows
into a water reservoir to maintain minimum storage capacity. The MSY of a water
aquifer may be a withdrawal rate equal to or less than the annual recharge rate,
which becomes critical in cases where the aquifer is covered by a heavy rock over-
burden. In these cases, excess withdrawal can result in costly irreversible loss in
aquifer capacity.
Once some basic economic estimates have been established for environmental
service flows relative to water reservoirs, etc., it is possible to select instruments to
accomplish more efficient and/or equitable outcomes. Economists prefer instruments
that provide incentives and allow a range of choices as opposed to command and
control instruments. Examples include taxes, subsidies, and auctioning of assimila-
tive capacity up to some resource constraint of SMS. Well-defined property rights
are a recurring theme of economists, and this is equally true of any changes in prop-
erty or use rights related to environmental service flows.
10.4 CASE STUDIES
The following four case studies of economic analysis of soil degradation and restora-
tion represent variation in scale, location, method, and analysis. The first case study
utilizes a metaproduction function approach to identify the factors (including soil
and land degradation) related to growth in agricultural and food output in a sam-
ple of 23 developing countries from 1971 to 1980. Follow-up analysis by Enver and
Hitzhusen in 2006 is also discussed. The second case is focused on estimating the
benefits of extended hydropower production from reduced soil erosion and sedimen-
tation of the Valdesia Reservoir and hydroplant in the Dominican Republic (DR). The
third case presents the results of several benefit-cost studies in Ohio to determine the
economic off-site impacts of soil agriculture and coal strip mining soil erosion on
lake, harbor, and drainage ditch dredging costs, lake-based recreation and residential
housing values, and water treatment costs. The fourth case presents the results of two
studies of the downstream benefits of the CRP in Ohio including reduced off-site
erosion impacts, wildlife habitat, and potential production of cellulosic-based bio
(ethanol) energy.
10.4.1 S oil and l and d egradation and a g g rowth M odel (C aSe 1)
A study by Zhao et al. (1991) focused on identifying the factors that determine the
agricultural production growth rate and on testing the effects these factors have on
agricultural growth in developing countries. Specifically, this study involved statisti-
cal estimation of an aggregate agricultural growth function based on cross-country
data for 23 developing countries. Special attention was devoted to environmental
degradation, agricultural pricing policy, and the policy implications resulting from
the effects these variables have on agricultural and food production growth.
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