Miscanthus Agronomy Guide
Giant miscanthus is a perennial warm season grass native to Asia. Other varieties of miscanthus exist, but giant miscanthus has shown the greatest potential as a bioenergy crop due to its high yield potential and its sterility. Research plots in Missouri have indicated miscanthus can yield between 12 tons and 15 tons per acre. The productive life span for giant miscanthus can reach up to 25 years. Missouri’s climate and soils fit well with giant miscanthus requirements.
Giant miscanthus can be grown on a wide range of soil types. According to the NRCS, the best production areas for giant miscanthus are well-drained soils with pH levels between 5.5 and 7.5 and medium to high fertility. Giant miscanthus is also noted for its ability to produce acceptable yields on marginal land, and it can even rejuvenate eroded soils in some cases.
The planting date for giant miscanthus is typically in the spring after the last frost, which is around April 15 in Missouri. Miscanthus grows best when planted in a finely tilled field. Operations such as disking, harrowing and/or culti-packing will be needed. Initial field preparation may include fertilizer and lime, if indicated by a soil test, and herbicide application. Liming material can be applied and incorporated to adjust the pH balance. Giant miscanthus is propagated by rhizomes, which are underground spreading stems. Giant miscanthus is a sterile hybrid and does not produce seed. Availability of rhizomes can be a challenge as the supply channel is not well-established. Rhizomes require special care, including cold storage, prior to planting. Producers should check that their suppliers deliver recently harvested rhizomes that have been held in cold storage, and the rhizomes should still be in senescence. NRCS recommends planting rhizomes at a 2-inch to 4-inch depth, 30-inch row spacing and approximately 6,000 rhizomes to 7,000 rhizomes per acre. Giant miscanthus rhizomes can be planted by using a modified corn planter, potato planter or a vegetable planter. After planting, the field could be rolled to improve soil contact with the planted rhizomes.
Fertilizer application in the establishment year will be based on soil test recommendations. Nitrogen tends to not be used due to weed competition in the establishment year. During the following years, fertilizer will be needed depending on nutrient removal rates of the harvested biomass crop and soil test recommendations. Nutrient removal rates are fairly low if miscanthus is harvested for bioenergy due to the plant’s ability to store nutrients in the rhizome portion of the plant that remains underground. Current recommendations (Heaton et al. 2012) suggest adjusting the fertility prior to planting within these ranges:
- Nitrogen – 5 pounds to 9 pounds per ton dry matter removed
- Phosphorus – 1.5 pounds per ton dry matter removed
- Potassium – 5 pounds to 9 pounds per ton dry matter removed
Giant miscanthus is very susceptible to weed competition during the first year. Herbicide application may be needed in that year and the following one to control weeds before the stand is fully established. In the establishment year, the miscanthus crop will not be fully developed and will require mowing or burning to reset the crop for the next growing season. A portion of the giant miscanthus crop may need to be replanted in year two if plants did not initially establish.
Harvest and Storage
Optimal harvest time for Missouri is between November and February. It should be after a killing frost and before growth in the spring. It is important to wait until the miscanthus crop contains less than 20 percent moisture. Conventional hay or silage harvesting equipment can be used to harvest giant miscanthus. The transportation equipment used will vary depending on the end destination. High-speed tractors and bale wagons can move bales to the field edge or nearby storage locations. Trucks with flatbed trailers can transport bales from field edge to further storage locations or end-users.
The transportation equipment used will vary depending on the end destination. High-speed tractors and bale wagons can move bales to the field edge or nearby storage locations. Trucks with flatbed trailers can transport bales from field edge to further storage locations or end-users.
Storage systems must minimize dry matter loss and protect the quality of the miscanthus before transporting to the end-user. Storage losses will vary by storage system (inside or outside), time in storage and weather conditions for bales stored outside. Inside storage is the best method for reducing storage loss, but constructing storage structures, improving land surfaces in storage areas or using tarps to cover bales increases storage costs. Acceptable storage losses, storage costs and end-user product needs will determine the appropriate storage system.
Casey, Allen, J. Kaiser, and R. Cordsiemon. 2011. Fact Sheet for Planting and Managing Giant Miscanthus in Missouri for the Biomass Crop Assistance Program (BCAP). USDA-Natural Resources Conservation Service, Plant Materials Center. Elsberry, MO 63343.
Dolginow, Joseph and Ray Massey. 2013. Switchgrass and Miscanthus: Economics of Perennial Grasses Grown for Bioenergy. Publication G4980. Columbia: University of Missouri Extension.
Heaton, Emily, Nicolas Boersma, John Caveny, Thomas Voigt, and Frank Dohleman. 2014. Miscanthus for Biofuel Production. eXtension. Accessed February 11, 2014.
Williams, M. and J. Douglas. 2011. Planting and Harvesting Giant Miscanthus as a Biomass Energy Crop. Technical Note 4. Plant Materials Program, USDA-Natural Resources Conservation Service.