Harvesting System Design and Performance - Engineering and Science of Biomass Feedstock Production and Provision - page 83

Table 5.1 Approximate moisture content and bulk density recorded while performing a
crop- specific operation a

Density
kgWMm −3

Moisture %
wet basis Product kg DM m −3

Wholesugarcane 65 200 70

Bundled whole cane 65 400 140

Billeted sugar cane 65 350 120

Shredded sugar cane 65 290 100

Billetedsorghum—300mmTLC b 65 215 75

Choppedsorghum—60mmTLC 65 310 110

Choppedsorghum—6mmTLC 65 360 125

Shredded stacks of corn stover 24 60 45

Round baled corn stover 24 135 105

Square bales corn stover 24 190 145

Choppedcornstover 47 140 75

Bagged and chopped corn stover 47 290 155

High-moisture ear corn in field 32 625 425

Dry ear corn in crib 13 450 390

High-moisture shelled corn in field 28 640 460

Dry shelled corn 12 770 675

High-moisture cobs 47 220 115

Dry corn cobs 6 165 155

Ground corn cob 9 270 245

a Adapted from [ 8 ]
b TLC theoretical length of cut

be done at higher moisture content. Furthermore, the moisture content often also
dictates the storage method adopted. Table 5.1 provides moisture content recorded
while performing various crop-specific operations.
Biomass yield and biomass quality, in addition to morphological properties,
depend on harvest time. Delayed harvest results in a lower biomass yield because of
the loss of leaves and tops. It also results in lower crop moisture content, which
eliminates the need for field drying, especially for energy grasses. Furthermore,
delayed Miscanthus harvest has been shown to improve combustion quality because
of reallocation of the minerals from the stems to the rhizomes [ 7 ]. Thus, autumn
Miscanthus harvest reduced yield by 35 % but also reduced ash content by 38 %,
potassiumcontentby67%,chloridecontentby75%,nitrogencontentby20%,and
moisturecontentby48%[ 7 ]. The lower nutrient content in aboveground-harvested
biomass also reduces nutrient demand for the subsequent cropping season.

5.2.2 Biomechanical Properties

Biomechanical properties affect many mechanical actions involved in bioenergy
crop harvesting, such as bending, cutting, conveying, size reduction, and densifica-
tion. Each of these actions can be performed in a variety of ways, and the selection