Sarah Hirsh, Agriculture Agent | shirsh@umd.edu; Haley Sater, Agriculture Agent; and Jon Moyle, Extension Poultry Specialist
University of Maryland Extension
Giant miscanthus (Miscanthus × giganteus) is a perennial warm season grass known for its high biomass yield and adaptability to various growing conditions. This species of miscanthus is a sterile hybrid typically propagated by rhizomes. It can grow up to 12 feet tall with roots 8 feet deep. Giant miscanthus reaches its full biomass yield potential in the third growing season, where it can yield 10 to 15 tons per acre (Heaton et al., 2010). Giant miscanthus is used in Maryland as a bedding material in poultry houses. It can also be used as a biomass crop for fiber-based products, a bioenergy crop, and has environmental uses including erosion control, carbon sequestration, and as a buffer against nutrient runoff.
The University of Maryland Extension performed a three-year research trial growing giant miscanthus on marginal land facing severe deer pressure, saltwater intrusion and waterlogging (Figure 1).
We found that giant miscanthus successfully grew with only a slight yield reduction. In the 10-acre field where the experiment was conducted, 20 one-meter square plots were harvested to calculate biomass yield. Yield on average in year one was 2.8 tons dry biomass per acre and yield on average in year two was 4.8 tons per acre (Figure 2). Average first- and second-year yields on prime land for growing miscanthus would be 3 tons per acre and 5-6 tons per acre, respectively. Giant miscanthus does not reach its full biomass yield potential until the third growing season, where it can ideally yield between 7-12 tons per acre (Kalmbach, et al., 2020).
In the 20 one-meter square plots where yield was taken, levels of sodium (Na) in the field ranged from 57-510 ppm Na, with an average of 174 ppm Na. This level of Na would cause stress that would result in yield loss to corn or soybean. A normal range of Na in Delmarva row-crop land is 5-40 ppm (Delmarva Saltwater Intrusion, University of Delaware, 2024). Higher concentrations of Na correlated somewhat with miscanthus biomass yield, more so in the second year than in the first year (Figure 3).
The entire study field stayed waterlogged during the winter months. The duration of waterlogging was observed to affect giant miscanthus growth and yield potential. Areas of the field where the soil stayed saturated throughout the winter and summer months had dramatically reduced giant miscanthus growth compared to areas of the field where the soil stayed saturated in the winter months but only intermittently during the summer months. In the year-round waterlogged parts of the field, giant miscanthus had shorter stand height, weaker stems and experienced lodging (Figure 4). The miscanthus grew equally well in the parts of the field that were intermittently flooded in the summer compared to the driest parts of the field (based on soil moisture sensor data; Figure 4).
The field had heavy deer pressure based on edge-of-field wildlife camera photos and observed deer tracks and paths in the field (Figure 5). However, no deer browsing of giant miscanthus was observed in the field.
Research conducted on Maryland farms has demonstrated that giant miscanthus is a versatile and resilient crop that can be grown on marginal land where other traditional agronomic crops can no longer be profitably grown. Its ability to withstand deer damage, saltwater intrusion and waterlogging make it a valuable option for farmers in Maryland looking to diversify their crops and improve the sustainability of their operations. However, access to equipment and markets may be barriers to farmers growing giant miscanthus, and we do not recommend this crop prior to addressing these factors.
Sources cited:
Agriculture and Salt Issues. (2024). Delmarva Saltwater Intrusion, University of Delaware, October, 10, 2024, sites.udel.edu/delmarvasalt/home-page/agriculture-and-salt-issues/.
Heaton, E., Moore, K., Salas-Fernandez, M., Hartzler, B. Liebman, M. and Barnhart, S. (2010). Giant Miscanthus for Biomass Production. Iowa State Fact Sheet. AG201. https://store.extension.iastate.edu/product/12611
Kalmbach, B., Toor, G., & Ruppert, D. (2020). Soil Fertility Recommendations-Nitrogen, Phosphorus, and Potassium Requirements of Miscanthus (EB-443).
