Agriculture Reference
In-Depth Information
increase in activity from day 1 to a peak on day 7, followed by a gradual decrease
thereafter (Castaldi et al.
2008
). Raut et al. (
2008
) reported an increase in protease
activity up to the 9th-12th day of the experiment, followed by a gradual decrease—
this observation was made with a properly aerated compost pile. Interestingly, with
an un-aerated compost pile, an increase in protease activity up to the last day (21st)
of the experiment was observed. The protease activity in dairy manure with rice
chaff was determined with three different piles. In piles 1 and 2, the thermophilic
stage was reached after 7 days, while the peak temperature reached after 17 days in
pile 3. The protease activity was highest at the initial stages in pile 1 and 2, followed
by a gradual decrease in activity; while the highest protease activity associated with
pile 3 was reached after 10 days (Liu et al.
2011
). The protease activity was as-
sociated with a number of
Bacillus
sp. during the early phase of animal manure
composting. Proteases from
B. stearothermophillus
were found to be activated in
the presence of calcium and ferrous ions during the aerobic degradation of sludge
compost (Kim et al.
2002
).
6.6.2
Cellulases and Hemicellulases
Cellulases and hemicellulases include a wide array of enzymatic machinery which
plays significant roles in the degradation of organic matter, particularly plant matter
and lignocellulosic residues. These enzymes have decisive influence on the carbon
cycle and also affect the overall nutrient cycle during composting. More than any
other substrate, the breakdown of cellulose limits the formation of compost (Goyal
et al.
2005
). He et al. (
2013
) reported the highest cellulase and β-glucosidase activ-
ity associated with the thermophilic
Bacilli
(predominantly
Bacillus
sp.) on days
12-14, over the 45 days composting period. Goyal et al. (
2005
) studied the changes
in cellulase and xylanase activity associated with the breakdown of different com-
post types including sugarcane trash + cattle dung (4:1), sugarcane trash + cattle
dung (1:1), press mud, poultry waste and water hyacinth. An increase in cellulase
activity was observed from the initial period up to 30 days followed by a sequential
decrease until the end of the study period (90 days). The highest cellulase activity
was observed with water hyacinth, followed by sugarcane trash + cattle dung (1:1),
press mud, poultry waste and sugarcane trash + cattle dung (4:1). The xylanase ac-
tivity showed a steady increase from the initial period and the highest activity was
recorded on day 60 of the composting period, followed by a decrease in activity to-
wards the end of the study period. The highest xylanase activity was observed with
water hyacinth followed by press mud, sugarcane trash + cattle dung (1:1), poultry
waste and sugarcane trash + cattle dung (4:1). The thermophilic stage was reached
after 14 days and thermophilic bacteria count was highest during this stage. The
thermophilic bacteria count was the highest in sugarcane trash + cattle dung (1:1),
followed by poultry waste and press mud piles. The differences in the phasing of
the cellulases and xylanase activity are also an indication of change in the structure
of the microbial community and indicate the emergence of thermophilic cellulolytic
bacteria followed by their xylanolytic counterparts. The study also indicates the
