Emily Heaton | Assistant Professor of Agronomy, Iowa State University and co-authors: Collin De Graaf, Valeria Cano, Perla Carmenate, Tyler Donovan, and Danielle Clark
If you have been driving in rural eastern Iowa and noticed a lot of choppers and wagons, you might have been seeing the UI Biomass Fuel Project Miscanthus harvest.
What the what?
Figure 1. Miscanthus harvest in eastern Iowa, where more than 1000 acres are being grown for the University of Iowa power plant. Photo credit: Nicholas Boersma
Miscanthus (Miscanthus × giganteus) is perennial warm-season grass used for energy and products in Europe, and increasingly, in the US. The University of Iowa (UI) has been developing Miscanthus as a replacement for coal in the UI power plant since 2013 as part of the Iowa Biomass Fuel Project (BFP). Using Miscanthus, wood chips, and oat hulls from Quaker oats, the UI plans to be completely off coal by 2025! The Heaton Lab and CLG partner with UI to provide agronomic and extension support to the BFP.
Why Miscanthus?
Miscanthus is a good choice for the UI because it is one of the most productive crops that can be grown in temperate climates like Iowa (producing ~8 tons of dry biomass per acre per year) and it does it without much need for fertilizer or pesticides, making it a very environmentally friendly crop. It has a big root system, like other perennial grasses, so it is great for holding soil and cleaning water, as well as providing a home to critters above and below ground (Figure 2). In addition to energy, Miscanthus is also being used for poultry bedding, mulch, and erosion control.
Figure 2. Miscanthus (left) has been shown to improve water infiltration and protect soil better than annual row crops like corn (right). Photo credit: Emily Heaton
So why is Miscanthus being harvested at the end of winter? A few reasons:
1) it needs to be dry if it is going to be efficiently burned, so the crop dries all winter in the field.
2) Leaving it in the field saves on storage.
3) Letting the plant fully senesce lets the crop to recycle nutrients from the shoots back to the below-ground rhizomes for use the following season.
4) Over the winter Miscanthus slows blowing snow, holds soil and provides shelter for wildlife.
Now that the crop has been harvested, new miscanthus shoots will start emerging when soil temperatures reach 50 ℉, so hopefully any day now!
Harvest Methods
Silage Chopping:A silage harvester can harvest whole plant material after it dries down in the field (Figure 1). Chopped material is blown into carts or traditional trailers similar to corn silage harvesting. If a cart is used, a tractor trailer stationed at the edge of the field can transport the miscanthus to storage or directly to the plant for energy generation (Figure 3). Check out a harvester in action here.
Figure 3. University of Iowa Miscanthus harvest. The fluffy biomass is hauled by truck to storage in plastic silage bags before use. Photo credit Emily Heaton
Mowing and baling: Miscanthus can be baled into round or square bales (Figure 4) similar to corn stalks. Travel and transport can be greatly improved with baling to increase crop density.
Figure 4. Miscanthus in round or square bales. Photo credit: ISU Biomass
Our research indicates a little of these crops can go a long way: replacing consistently low-yielding corn/soy with a perennial grass can meet Iowa’s water goals (reduce N in water by ~40%) while making farmers more money. That’s a refreshing alternative to the billion-dollar price tag we usually hear for improving agriculture’s water quality impact in Iowa! Stay tuned to CLG and @ISUBiomass to learn more about putting perennials like Miscanthus into underperforming row crop fields.
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