Sweet potato better than corn for ethanol production

Nov 11, 2008
Sweet potato better than corn for ethanol production

In experiments, sweet po tatoes grown in Maryland and Alabama yielded two to three times as much carbo hydrate for fuel ethanol pro duction as field corn grown in those states, Agricultural Research Service (ARS) sci entists report. The same was true of tropical cassava in Alabama.

The sweet potato carbo hydrate yields approached the lower limits of those produced by sugarcane, the highest-yielding ethanol crop. Another advantage for sweet potatoes and cas sava is that they require much less fertilizer and pesticide than corn.

Lew Ziska, a plant phys iologist at the ARS Crop Systems and Global Change Laboratory in Beltsville, MD, and colleagues at Beltsville and at the ARS National Soil Dynamics Laboratory in Auburn, AL, performed the study. The research is unique in com paring the root crops to corn, and in growing all three crops simultaneously in two different regions of the country.

The tests of corn, cassava and sweet potato were in the field at Beltsville and in large soil bins at Auburn. For the sweet potatoes, carbohydrate production was 4,692 tons an acre in Alabama and 6,353 tons an acre in Maryland. Carbohy drate production for cassava in Alabama was 4,940 tons an acre, compared to 1,434 tons an acre in Maryland.

For corn, carbohydrate pro duction was 1,692 tons an acre in Alabama and 2,760 tons an acre in Maryland. The disadvantages to cas sava and sweet potato are higher start-up costs, par ticularly because of in creased labor at planting and harvesting times. If eco nomical harvesting and pro cessing techniques could be developed, the data suggests that sweet potato in Maryland and sweet potato and cassava in Alabama have greater potential than corn as ethanol sources.

Further studies are need ed to get data on inputs of fertilizer, water, pesticides and estimates of energy efficiency. Overall, the data indicate it would be worth while to start pilot pro grams to study growing cassava and sweet potato for ethanol, especially on marginal lands.

The additional research could help develop new biofuel sources without di verting field corn supplies from food and feed use to fuel. — WLJ