Beginning in the 1970's, the U.S. Fish & Wildlife Service decreased emphasis on agriculture on National Wildlife Refuges and increased emphasis on the natural wildlife foods produced in wetlands to provide a healthy, diverse diet for waterfowl. However, farming remains an important tool for refuge management.
Agricultural grains can provide a high-energy carbohydrate source for migrating waterfowl, but they provide only a portion of total nutrients needed and therefore are used only as a supplement, not a substitute for natural wetland food.
Agriculture also is one of the tools used to maintain long-term productivity of wetland units. Unmanaged wetlands can quickly convert to weeds, grassland, or forest. An occasional season of farming will set back this natural succession.
A third purpose of the cropland management program is to maintain open conditions in units prior to conversion to another habitat type. Funding and staffing constraints may delay desired habitat restoration for several years. If floodplain areas are left idle, they can quickly grow up to thick stands of willow, cottonwood, and weeds.