Conservation Programs: Balancing Outcomes With a Selection Index

Many of the Nation’s conservation programs help to offset the negative effects of agricultural production by enhancing water quality, reducing soil erosion, and protecting wildlife habitats. One tool many conservation program managers use to balance multiple objectives is a “selection index,” which allows them to rank and select applicants based on how well the offered land provides environmental improvements in a cost-effective manner. In this index, different environmental and cost objectives are weighted by program managers’ perceptions of their relative importance (see 'Behind the Data'). However, gauging which environmental objectives should have the highest priority in these programs is tricky because price tags are generally not available to signal how much people value improving wildlife nesting grounds, for example, or making a stream clean enough for swimming. If new information about environmental preferences becomes available, program managers can, in theory, adjust the weights to align future program outcomes with the new preferences. In practice, little is known about the actual effects of such changes.

Using data from USDA’s Conservation Reserve Program (CRP), the Nation’s largest land retirement program, ERS researchers found that small changes in index weights did not markedly affect environmental outcomes at the national level. But doubling the index weight on any one objective (such as improving wildlife habitat) could result in a 15-percent improvement in that outcome. These findings suggest that if a conservation program generates environmental improvements that approximately match society’s preferences, little would be gained by fine- tuning the index weights. But if new information suggests that an alternative mix of environmental improvements is preferred, program outcomes can be affected by larger changes in weights. Changes in weights may not induce proportional changes in environmental improvements because some factors, such as which land will be offered for enrollment and which set of environmental problems will be addressed in a voluntary program, cannot be controlled.

Policymakers and program managers may find that varying the index weights by region or adjusting other program features, such as eligibility criteria or the mix of allowable land management practices, may also help bring about desired changes in CRPoutcomes.