VALUE-ADDED PRODUCTS FROM FORAGES AND BIOMASS ENERGY CROPS
Location: Cell Wall Biology and Utilization Research
Title: Harvesting and Storing of Two Perennial Grasses as Biomass Feedstocks
Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 24, 2010
Publication Date: April 30, 2010
Citation: Shinners, K.J., Boettcher, G.C., Muck, R.E., Weimer, P.J., Casler, M.D. 2010. Harvesting and Storing of Two Perennial Grasses as Biomass Feedstocks. Transactions of the ASABE. 53(2):359-370.
Interpretive Summary: Some perennial grasses, such as reed canarygrass and switchgrass, have high yields, low input needs, and grow on land unsuitable for human food production, making them attractive as biomass feedstocks for producing ethanol and other chemicals, thus reducing our need for crude oil. When harvested as biomass, these grasses are more mature and have much greater yield than when harvested for animal feed. Unfortunately little is known about the harvesting and storage of these grasses under such conditions. This research studied issues related to harvesting and storing these grasses as dry hay and silage. The three-year average yield of reed canarygrass was 21% less than switchgrass using a single-cutting system that occurred in August. When the crops were left standing over winter and harvested in the spring, yields were reduced 22%. Switchgrass tended to dry faster than reed canarygrass, but both dried faster than alfalfa, the most common forage grown in the U.S. Both grasses formed bales of similar characteristics, and losses in dry bales stored outside ranged from 4 to 15% depending on how the bales were wrapped. If the dry bales were stored under cover, average losses were only 3%. Ensiling bales at 40% moisture produced the lowest losses, 1%. These results indicate that farmers can get high yields from these grasses with a single cutting. These crops dry, bale similarly and have losses that are comparable to forages harvested for animal feed. These results will be useful for those interested in producing grasses for biomass uses.
Some perennial grasses, such as reed canarygrass (RCG) and switchgrass (SWG), have prolific
yield and low inputs, making them attractive as biomass feedstocks. When harvested as biomass, these grasses are more mature and have much greater yield than when harvested as animal forage. Much is unknown about how harvest equipment performance and storage characteristics are affected by these crop conditions. The objective of this research was to determine the crop yield and drying rate, baling rate, bale density, and bale storage characteristics of these grasses harvested as a biomass feedstock. After the establishment year, the three year average yield of RCG was 21% less than SWG (7.70 vs. 9.69 Mg DM/ha) using a single-cutting system that occurred in August. When the crops were left standing over winter and harvested in the spring, DM yields were reduced by 17 and 26% for SWG and RCG, respectively. When crop yield was similar, switchgrass tended to dry faster than reed canarygrass. Drying rates of these grasses was faster than typically experienced with forage crops like alfalfa. Bale density averaged 163 kg DM/m3 with no significant differences between crops or type of wrap (twine or net). Dry bales stored outdoors for 9 to 11 months averaged 3.8, 4.8, 7.5, 8.7 and 14.9% DM loss for bales wrapped with plastic film, breathable film, net wrap, plastic twine, and sisal twine, respectively. Bales stored under cover averaged 3.0% DM loss. The chemical and physical properties of bales stored outdoors were spatially variable. Preservation by ensiling in a tube produced average DM losses of 1.1% at an average moisture of 39.9% (w.b.).