Switchgrass and Giant Miscanthus Agronomy - Engineering and Science of Biomass Feedstock Production and Provision - page 47

Fig. 3.5 Proposed US growing region for “Illinois” type of Miscanthus × giganteus . It is intended
to identify areas suited to growing this grass. Additional feedstocks may also grow well and be
productive in this region
and biomass production [ 62 ], but soils of low fertility can lengthen the time required
to reach full establishment by several growing seasons.
For a C4 species, established M . × giganteus plants are extremely cold tolerant,
but winterkill of fi rst-year plantings has occurred in the Midwestern USA [ 71 , 76 ].
Clifton-Brown and Lewandowski [ 77 ] reported that 50 % of newly planted rhi-
zomes can be killed by soil temperatures of −3.4 °C at the 5-cm level. Established
plants, however, have survived air temperatures lower than −20 °C in central Illinois
[ 62 ]. Conversely, biomass production in subtropical settings can be limited by early
fl owering that restricts vegetative growth. Because it is capable of photosynthesiz-
ing optimally at cool temperatures above 12 °C [ 78 ], giant miscanthus not only
begins growth in the spring earlier than many other warm-season grasses, but is also
able to continue growth into the late summer and early autumn, again past the time
when many other C4 grasses have ceased growth for the year [ 79 ]. The early start
and late fi nish contribute to its annual productivity. Thus, the authors believe this
crop is best planted in temperate regions.
Given the concerns about cold tolerance in fi rst-year plantings, the water require-
ments for productive growth, and the productivity of other feedstocks, the authors
propose that the commonly planted clonal form of giant miscanthus, the “Illinois”
type, is best produced in the central region of the eastern USA (Fig. 3.5 ). In areas to
the south of this region, feedstocks such as some lowland switchgrass varieties,
energycane ( Saccharum spp.), and napier grass ( Pennisetum purpureum ) are likely
to be better suited and more productive than giant miscanthus. Areas to the west of