Agriculture Reference
In-Depth Information
During composting acidic pH < 5.0 environment is facilitated by fungal micro-
organisms optimally at temperature ranges between 22.5 and 45 °C (Finstein and
Morris
1975
). At this range of temperature fungal activity limits in term of fungal
cell destruction without affecting spores (Boulter et al.
2000
). As compost reached
at 60 °C and above thermophilic microorganisms dominate the composting process.
Composting of organic materials or waste influenced by microbial population
having multifarious chemical and biological properties. Several enzymatic activity
involves cellulase, xylanase and protease have provision for decomposition. Fur-
ther, generally, C:N ratio index confirms the maturity of compost. As a result of
decomposition, heat output and temperature decreased. At this duration, mesophilic
microorganisms that grows at < 40 °C recolonize in compost. Therefore, suppres-
sion of pathogens and/or disease is largely induced during curing, because most
bio-control agents recolonize compost.
12.4
Principles of Composting
Composting and recycling is becoming an efficient treatment for organic wastes
where in the available literature revealed the limited attention has been paid on
microbiological aspects of compost science (Ryckeboer et al.
2003a
; Benito et al.
2003
; Tiquia
2005
; Liu et al.
2011
). Newer techniques and complementary methods
to characterize microbial diversity and evolution during composting may undoubt-
edly develop the future prospectus with recent concern in this applied aspect of
composting of agricultural apprehension. An outline of the composting process is
given in Fig.
12.1
. Composting of organic matter includes food waste, agro-wastes,
plant biomass residues, animal manures etc. The process involved various groups of
bacteria, fungi, protozoan, rotifers etc. which cater the process on variable tempera-
ture, pH, oxygen concentration, carbon nitrogen ratio etc. these factors influence
the dynamics of decomposer community as well as process of compost formation of
high value. During compost or recycling of agricultural wastes process is affected
by environmental stresses (Peigné and Girardin
2004
). Some environmental burden
of composting can be resolved out by using such assessment i.e., gas emission (CH
4
,
CO
2
, N
2
O, NH
3
etc.) and volatile organic compounds (VOCs). Colón et al. (
2010
)
studied and confirmed that stable and final compost have not any remaining patho-
gen and phytotoxic elements, though it has higher amount of C:N ratio. The good
quality of compost can be ascertained by particle size of compost, moisture and
amount of impurities mixed. The process involve long duration of accomplishment
ranges between 6 to 12 months (Kakezawa et al.
1990
). The microorganisms obtain
moisture from waste, oxygen from the air and nutrients from the organic wastes.
Give off carbon dioxide, moisture and energy (Groenhof
1998
): these reproduce
themselves and eventually die with the reduction in oxygen index as a principal
factor for microbial survival (Scaglia et al.
2000
). Some of the energy is used for
growth and movement; the rest is given off as heat which one tries to conserve in a com-
post heap. As a result, the heap passes through warming-up, increases temperature,
