Switchgrass and Giant Miscanthus Agronomy - Engineering and Science of Biomass Feedstock Production and Provision - page 37

Establishing both switchgrass and giant miscanthus, as well as other perennial
grasses, is more challenging than establishing most annual row crops, but once
established, long-term management is generally easier for the perennial crops.

3.2 Switchgrass

Switchgrass, a perennial, C4 grass, is a dominant member of North American
tallgrass prairie. It has broad adaptation with great genotypic and phenotypic varia-
tion, and its range extends from Central America to southern Canada and from the
eastern seaboard to Arizona and Nevada in the western USA [ 8 - 12 ]. It is a coarse
grass, typically 0.5-3.0 m tall, with roots growing down to as deep as 3 m [ 8 , 10 ].
Depending on its particular genetics, a switchgrass plant can produce short rhi-
zomes that form tight bunches developing a plant with a bunch-type appearance or
produce long, active rhizomes that form sod [ 13 ].
Switchgrass has been planted as streamside buffers, fi lter strips, wildlife habitats,
and windbreaks for conservation. Shortly after it becomes established, the grass
typically attracts wildlife, which can add recreational benefi ts to an area [ 14 ]. It can
improve the environment and is also planted frequently in prairie restorations [ 11 ,
12 , 15 ]. These restored sites help reduce soil erosion and remove toxins and excess
nutrients that would otherwise run off into streams [ 14 ]. Switchgrass also helps
rejuvenate the soil structure by adding organic matter through its extensive root
system [ 14 , 15 ].
Switchgrass has been used in the forage industry since the 1940s and is now a
leading biofuel feedstock [ 16 - 19 ]. It is relatively easy to establish, is adapted to
many environments, requires low-management inputs, and can be harvested with
currently available equipment [ 20 ].

3.2.1 Cultivar Selection and Seed Quality

As in most plant production activities, the fi rst step in establishing and sustainably
producing switchgrass is the selection of the best cultivar for a region and climate.
Switchgrass is widely distributed and well adapted to wide geographic regions in
North America; its adaptation and performance are determined by the hardiness
zone and latitude of its origin. Currently, many switchgrass cultivars are commer-
cially available, and the adaptation of these cultivars covers wide geographic areas
based on their origins (Fig. 3.2 ).
In general, moving switchgrasses that originate in the north to the south is not
recommended because early fl oral initiation reduces biomass yields [ 21 , 22 ], and in
some cases, switchgrasses do not survive when moved from north to far southern
locations [ 23 ]. Most of the switchgrasses that originate in the south are later-maturing
cultivars that have higher yield potential than switchgrasses from northern areas