Environmental Engineering Reference
In-Depth Information
DID YOU KNOW?
With regard to establishing switchgrass, no single method can be suggested
for all situations (Parrish et al., 2008). No-till and conventional tillage can be
used to establish the crop. When seeded as part of a diverse mixture, planting
guidelines for warm-season grass mixtures for conservation plantings should
be followed. Several key factors can increase the likelihood of success for
establishing switchgrass, including the following:
•
Plant switchgrass after the soil is well warmed during the spring.
•
Use seeds that are highly germinable and plant 0.6 to 1.2 cm deep, or
up to 2 cm deep in sandy soils.
•
Pack or firm the soil both before and after seeding.
•
Provide no fertilization at planting to minimize competition.
•
Control weeds with chemical or cultural control methods.
the viability of an energy crop such as switchgrass hinges on continued reductions in
cellulosic ethanol conversion costs and sustained improvements in yield and produc-
tivity through breeding, biotechnology, and agronomic research.
Although it is an important biofuels crop, switchgrass does have limitations.
Switchgrass is not optimally grown everywhere. For example, in the upper Midwest
under wet soils, reed canarygrass (
Phalaris arundinacea
) is more suitable, while
semitropical grass species are better adapted to the Gulf Coast region. State and
local efforts are testing alternatives to switchgrass, including reed canarygrass, a
tall, perennial grass that forms extensive single-species stands along the margins
of lakes and streams;
Miscanthus
(often confused with “elephant grass”), which is
a rapid-growth, low-mineral-content, high-biomass-yield plant; and other species.
With regard to long-run sustainability, the ecology of perennial grassy crops
favors a multiplicity of crops or even a mix of species within the same area. Both
ecological and economic sustainability favor the development of a range of herba-
ceous species for optimal use of local soil and climatic conditions. A mix of several
energy crops in the same region would help reduce the risk of epidemic pests and
disease outbreak and optimize the supply of biomass to an ethanol or biopower plant
because different grasses mature and can be harvested at different times. Moreover,
development of future energy crops must be evaluated from the standpoint of their
water use efficiency, impact on soil nutrient cycling, effect on crop rotations, and
environmental benefit (improved energy use efficiency and reduced greenhouse gas
DID YOU KNOW?
The main advantage of using switchgrass over corn as an ethanol feedstock is
that its cost of production is generally about half that of grain corn and more
biomass energy per hectare can be captured in the field (Samson et al., 2008).
