Wednesday, January 17, 2018

Growth Spurts: Choosing Cellulosic Biofuel Crops

According to the U.S. Environmental Protection Agency, 288 million gallons of cellulosic biofuel must be blended into the U.S. gasoline supply in 2018. Although down slightly from last year, the industry is still growing at a modest pace.

A new multi-institution report backed by the U.S. Department of Energy and the Sun Grant Initiative provides practical agronomic data for five cellulosic feedstocks - switchgrass, Miscanthus, sorghum, energycane, and prairie mixtures - in long-term trials spanning a wide geographical area.

Crops were grown for five to seven years in multiple locations and with varying levels of nitrogen fertilizer. Although most of the crops are known to tolerate poor soil quality, the researchers found that they all benefited from at least some nitrogen. For example, Miscanthus did best with an application of 53.5 pounds per acre.

Due to shortages in plant materials, Miscanthus and energycane were grown on smaller plots than the other crops, but researchers say the new results are still valuable for producers.

Prairie mixtures, which were grown on land enrolled in the Conservation Reserve Program (CRP), also benefitted from added nitrogen. Yield kept increasing with the addition of up to 100 pounds per acre. But even though it increased yield, it is economically not profitable to use more than 50 pounds of nitrogen per acre.

And although most of the crops are somewhat drought-tolerant, precipitation made a difference.

The results showed the greatest yield potentials for lowland switchgrass varieties in the lower Mississippi valley and the Gulf coast states, whereas Miscanthus and prairie mixture yields are likely to be greatest in the upper Midwest.

Prairie mixtures, which are typically grown on CRP land to conserve soil, didn’t live up to their potential in the study.

Energycane could reach very high yields, but in a relatively limited portion of the country.

The crop that shows the highest potential yields in the greatest number of locations is sorghum. The annual crop is highly adaptable to various conditions and might be easier for farmers to work with. In terms of management, it is almost the same as corn. It germinates and grows so quickly, weed control is not a big issue. If you plant by early June, it will be 15-20 feet tall by September. It also has good drought tolerance.

Downsides to sorghum? It’s wet at harvest and can’t be stored. It also requires nitrogen and can lodge, or collapse, prior to harvest in wet or windy conditions.

Biomass production of herbaceous energy crops in the United States: Field trial results and yield potential maps from the multiyear regional feedstock partnership

Growth Spurts
Energy Farming
Plants and Seeds
Artwork: Sorghum vulgare

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