87
Miscanthus Production
<10 cm on two occasions, June 1 and June 18. Rain was adequate through the
remainder of the season. No further weed control was used.
Survival was recorded on May 5, 2016, when plants had emerged from winter dormancy. The plantlets stored cold in perlite or perlite + vermiculite and
knocked off at planting, had as fraction of survivors, 7/11; with mixture left
on, 8/11; small rhizome propagules, or actively growing rhizomes 9/11; all
other treatments 11/11. Some of the more vigorous plants in one border row
had extended runner rhizomes over 50 cm out into the surrounding area. In
December 2016 this plot had a biomass of 8.0 ± 1.9 t ha −1 (N = three samples of
0.81 m 2 ) comparable to the 2016 year 1 yield of the study by Alasmary (2020),
which was done immediately adjacent to this trial plot.
5.2.4 Weather
While climate change is a long-term transition that may alter the optimum
growth regions for M. × giganteus, changeable weather is the present challenge. Average winters have become warmer over much of the US, but occasional sudden changes are much more damaging to M. × giganteus. Late
spring frosts or sudden early autumn frosts can have large consequences
(Kaiser and Sacks, 2015). In springtime, energy expended in sending forth
shoots is lost when a sudden freeze severely injures them.
A major collaborative study of Miscanthus production and efforts to model
its productivity in the US (Lee et al., 2018) has 58 authors. It was initiated
in 2008 and compared Miscanthus with several other potential bioenergy
sources including switchgrass, forage sorghum, “energycane” which is a version of sugarcane, and mixed grasses. Weather and geography were obvious
variables. The duration and locations of trials for the different crops varied. For Miscanthus a 6-year study was done in five locations. At two initial locations, in Illinois and Indiana, there was high winter mortality of the
transplants which had been started from ~25 g propagules in a greenhouse
prior to planting in June/July 2008 (rather late). In Illinois 75% of plants were
lost. The severely damaged Indiana site was replaced by one in the Virginia
Piedmont in 2010. That site is climatically milder but with soils and terrain
generally less suited to annual row crops.
We observed signs of significant prior frost damage on early emerging
M. sacchariflorus Bluemel when we were planting on May 2, 2017, 2 weeks
after the expected date of the last killing frost in our climate. The year-old
plants in the study of Alasmary (2020) were ~50 cm tall by May 2, showing
damaged foliage. A 2-year-old (2015) trial plot which had not been harvested
the previous autumn had much shorter plants with far less damage (personal observation). Residual vegetation presumably delayed soil warming
and shoot emergence.
Sudden fall frosts are reported to damage first year M. × giganteus in
Illinois because the plants tend to remain green longer during their first year
(Boersma et al., 2015). This frost damage in turn reduces the translocation of