STARKVILLE, Miss. - A soon-to-be completed study by Mississippi State scientists recommends that farmers who leave standing stubble in rice fields after harvest may increase "waste" rice by 44 percent for waterfowl wintering in the Lower Mississippi Alluvial Valley.

The five-year university investigation, which was partially funded by the Arkansas Game and Fish Commission, into various post-harvest field practices also concluded that the "waste rice" - grain escaping collection by combines - method actually can save farmers money in production costs.

"Waste-rice is a valuable nutritional commodity for wintering ducks and geese," said Rick Kaminski, waterfowl biologist in MSU's Forest and Wildlife Research Center. Of critical concern, however, is the amount of waste rice remaining in early winter when waterfowl typically arrive to the region in significant numbers, he added. "Waste rice is disappearing during autumn before waterfowl arrive due to decomposition, germination and consumption by birds and rodents," Kaminski said.

To research the issue, a former MSU wildlife and fisheries graduate student and current graduate student Jennifer Kross of Boynton Beach, Fla., collected more than 7,000 samples from harvested rice fields throughout the Mississippi alluvial region during autumns 2000-04. Determining which post-harvest practices conserved the most rice for wintering waterfowl was one of their objectives.

"We evaluated the effects of disking, rolling, burning, mowing, and doing nothing to rice stubble after harvest," Kross said. "These practices were chosen because earlier research revealed most rice producers used one or more of these strategies after harvest."

On average, Kross said more waste rice - specifically, 93 pounds per acre - was found in late fall in standing stubble fields than in burned, mowed, rolled and disked fields, which produced 65, 60, 45 and 43 pounds per acre, respectively.

In fact, only standing stubble, burned, and mowed fields contained more than 45 pounds of rice per acre, which is considered the threshold for sustained rice-field feeding by mallard ducks.

"Below 45 pounds of rice per acre, mallards 'give up' feeding and abandon rice fields," Kaminski explained. In addition to retaining more rice for waterfowl, leaving stubble during winter is environmentally and agriculturally beneficial, he added.

Kaminski said Scott Manley, another former MSU graduate student, found winter-flooded rice fields where stubble was left intact lost only about 31 pounds of soil per acre during winter. Manley now is employed with Ducks Unlimited.

By contrast, fields that were disked and left to drain after winter rains lost nearly 1,000 pounds per acre. According to the research, rice producers may realize about a $30 per acre savings in production costs at spring planting because fewer weeds grew in standing stubble fields winter-flooded for waterfowl.

Considering all of the potential benefits, Kaminski said the report recommends leaving standing stubble in rice fields during winter as a "preliminary best management practice." The practice of leaving stubble in fields is an economical method to maximize waste rice, because tractor and other implement costs are eliminated.

Farmers may wish to burn a portion of the field, however, in order to produce patches of burned and unburned stubble, Kaminski said.

"When rice fields are flooded, the burned patches will become open-water landing and foraging areas for waterfowl," he explained. "When environmental regulations or agricultural practices prevent burning, patches may be mowed within fields to create open-water areas."

When mowing, Kaminski said farmers and waterfowl hunters must remember that standing rice and other crops cannot be "bush-hogged" or manipulated in any manner except to harvest the crops. To do so would cause the field to be considered as illegally "baited" for waterfowl hunting.

To farmers preferring to roll or disk stubble, Kaminski issued a warning: do so sparingly. These treatments result in waste-rice densities at or below the "giving-up" threshold, he said.