By Madelynn Connell and Emily Heaton
Many people in the Midwest have recently experienced the bitter-cold temperatures brought on by arctic air falling into the mid-latitudes. While these temperatures can make people rather uncomfortable, they are also potentially dangerous to miscanthus in the field.
Vulnerability of Young Miscanthus
Miscanthus x giganteas (miscanthus) is most vulnerable to extremely cold soil temperatures during the first winter after establishment. In particular, the rhizomes of miscanthus can be damaged by cold soil temperatures, and damage to the rhizomes can kill the whole plant. Also, freezing air temperatures can harm new vegetation, inhibiting the rhizomes from sprouting again. This is a concern when -36-degree Fahrenheit wind chill temperatures are experienced like on Thursday, February 13, 2020, in Ames, Iowa (Figure 1).
Soil Temperature Threshold
So, how cold really is too cold? Median lethal temperature of a plant is defined as when 50% of the rhizomes are killed. The lethal temperature of miscanthus is a 4 -inch depth soil temperature of 26 degrees Fahrenheit[i].
Figure 2 shows that on February 13, 2020, Ames, Iowa, experienced 4- inch depth soil temperatures of 32 degrees Fahrenheit. Fortunately, soil temperatures did not reach the 26 degrees Fahrenheit threshold in Central Iowa, but other parts of the state certainly did. As farmers begin to consider planting miscanthus, they also must consider how
increasingly cold winters will impact the 4- inch soil depth temperatures. Knowing which soil temperatures are most suitable for miscanthus production will increase the growth success of the crop.
Product of ISUBiomass Undergrad Team
[i] H.W. Zub, M. Brancourt-Hulme. 2010. "Agronomic and physiological performances of different species of Miscanthus, a major energy crop. A review." EDP Sciences 8.