Agriculture Reference
In-Depth Information
Table 6.1
(continued)
Compost type
Major bacterial groups
Enzyme(s)
Reference
Lignocellulosic substrates
(corn stover and prairie
grass)
Thermophilic microbial
consortium (TMC)
Cellulase,
xylanase
Zambare et al. (
2011
)
Saw dust and coffee residue
compost
Paenibacillus
spp. (
P.
woosongensis
)
Cohnella
sp.,
Streptomyces
spp.
Cellulase,
xylanase,
β-glucosidase,
mannanase
Eida et al. (
2012
)
Hot compost
B. subtilis
CMCase,
Avicelase and
β-glucosidase
Kim et al. (
2002
)
Rotting rice straw
B. subtilis
CMCase,
cellobiase
Shu-bin et al. (
2012
)
Lignocellulosic biomass
Bacillus
sp.
Endoglucanase
Nizamudeen and
Bajaj (
2009
)
counts for 1.5 × 10
9
t year
−1
of dry biomass for the conversion to bioethanol, thus
projecting the total potential bioethanol production from crop residues and waste
crops to approximately 491.0 GL year
−1
).
Sugarcane is among the principal agricultural crops cultivated in tropical coun-
tries. Bagasse is the residue obtained from the sugarcane after the processing of
sugarcane juice and is used as a source of sugar and ethanol production. It has an
advantage over other crop residues as it is a by-product, and does not require special
and costly collection and transportation measures. The annual world production of
sugarcane is 1.6 billion t, and it generates 279 million t of biomass residues (bagasse
and leaves). For the past three decades, bagasse and leaves have been explored for
use in lignocellulosic bioconversion (Beukes and Pletschke
2011
; Chandel et al.
2007
) (Fig.
6.2
).
As with other raw materials, when discussing the use of crop residues as raw
material for biofuel, their alternative uses should be considered. Of special impor-
tance is their use as soil conditioner and for increasing the levels of soil organic
matter, with important effects on soil structure, preventing erosion, the supply of
nutrients, acidification, and water holding capacity of soils, all affecting soil fertility
and health (Lal
2004
).
The contribution of the agricultural sector to emissions of climate change gases
is becoming better understood. At the same time, the potential role of the sector as
a means through which to tackle climate change, widely neglected in the past, is
becoming more widely acknowledged. The absorption potential of agricultural soils
could contribute significantly to constraining increases in greenhouse gas emission
levels, while also contributing to improvements in soil quality in some areas. In
addition to the measures listed above, other benefits of compost application may
have some relevance. Some of these measures include the replacement of chemical
fertilizers (implying avoidance of greenhouse gases related to their production),
