The (Hopefully) Good News
If ducks can weather the corn ethanol storm, good news may be on the horizon. The cellulosic ethanol industry, if implemented in a duck-friendly way, could be an asset to waterfowl production. The key lies in the nature of the feedstock, what land uses it displaces, and how it is harvested. In this context, all duck enthusiasts should be pulling for a perennial grass crop like switchgrass, as it clearly holds the most promise for waterfowl benefits.
Switchgrass, like other perennial plants being considered as biofuels, is a tall, dense grass that makes the most of the sun’s energy and the soil’s nutrients. The economics of cellulosic ethanol are all about the tons of biomass that can be grown on an acre of ground. Currently, switchgrass varieties being grown in the Prairie Pothole Region annually yield from 2 to 3 tons per acre. But new varieties being developed through advanced genetics technology may eventually yield as much as 10 tons per acre annually. Most importantly, grasses used to produce cellulosic ethanol are harvested after the growing season, in fall or winter. So the switchgrass stubble that emerges from snow banks to greet mallards in the spring will not be disturbed during the nesting season. The key is to cut the switchgrass high enough (ideally 12 inches or more) so that ducks perceive the stubble as attractive nesting cover.
Besides stubble height, there is another important variable in assessing the net effect of a perennial biomass crop on duck production. That variable is the previous use of the land now dedicated to growing a biofuel crop. If switchgrass is planted on cropland that used to be cultivated every year, the net effect on ducks will almost always be positive. Annually tilled crops (except for winter wheat) provide poor nesting habitat for ducks. But if switchgrass replaces CRP or native prairie, duck production will be negatively affected. Grassland left completely undisturbed (in the case of CRP) or grazed (in the case of native prairie) is generally more productive for ducks than grassland that is harvested every year, even if harvest occurs during the fall.
One important economic consideration for cellulosic feedstocks like switchgrass is the transportation distance from field to processing plant. At current switchgrass yields, the maximum transport distance is about a 50-mile radius. So policies intended to encourage the cellulosic ethanol industry should recognize the need to cluster dedicated biomass crops near proposed or existing plants, rather than, for example, allowing all 7.8 million acres of CRP in the Prairie Pothole Region to be opened up as a potential feedstock. To do so would ensure that more than 90 percent of the biomass would be too far from a processing plant to be used for fuel production.