Switchgrass and Giant Miscanthus Agronomy - Engineering and Science of Biomass Feedstock Production and Provision - page 42

Fig. 3.4 Switchgrass stands after 2 months of planting ( left ) and at anthesis ( right ) during the
establishment year, with ( bottom ) and without ( top ) preemergent herbicide
seedbed preparation [ 41 ]. Seeding rates ranging from 3 to 10 kg ha −1 are based on
seed weight and quality [ 14 , 15 ], and fi eld seeding rates should be adjusted based
on seed size and weight as well as PLS percentage, since switchgrass seed size
and weight vary among ecotypes and cultivars [ 15 ]. A stand density of 20 plants m −2
is considered excellent, can produce harvestable biomass during the establishment
year if weeds are controlled, and will typically reach full production in the second
growing season. A density between 10 and 20 plants m −2 is considered adequate, but
might require one or more seasons to reach full production. Poor stands have a den-
sity of less than 10 plants m −2 and should be overseeded or replanted [ 20 ].