Agriculture Reference
In-Depth Information
supplementary treatments either with micro-organisms (Kausar et al.
2010
; Amira
et al.
2011
) or with enzymes (Feng et al.
2011
).
3.2
Roles of Lignocellulose Biodegradation
in Composting
As implied by the prefix “bio” in biodegradation, one of the key roles of lignocel-
lulosic materials in a compost pile is to help support life. Since most composting
processes take place in the dark, the energy needed to support life cannot come di-
rectly from photosynthesis. Instead, the bacteria and fungi within an active compost
pile mainly consume the energy from sugars stored within the cellulose and hemi-
cellulose components. Meanwhile, and especially in the later stages of composting,
the lignin component is chemically transformed by further enzymatic action. The
subsections that follow will emphasize recent findings regarding the biological and
biochemical aspects.
3.2.1
Conditions Affecting Composting
As noted by Karadag et al. (
2013
), the outcome and speed of a composting opera-
tion can be profoundly affected by the starting composition of a pile. Differences
in ingredients of a mixture intended for composting govern such factors as the ratio
of carbon to nitrogen, the pH, and ultimately the distribution and abundance of bio-
logical organisms. Thus, the starting composition is a key determinant that affects
the goals of composting. In addition to the four main goals of composting that were
listed in the Introduction, Karadag et al. (
2013
) also list stabilization of organic
materials, minimization of landfilling, destruction of pathogens, minimization of
greenhouse gases, and reducing the cost of obtaining fertile soil.
3.2.1.1
C:N Ratio
It is well known that efficient composting requires a suitable proportionality be-
tween the elements carbon and nitrogen within the organic materials. Most lignocel-
lulosic materials, such as wood and dry grasses, are rich in carbon but contain little
if any bound nitrogen. Thus, it is a common practice to add plant-based biomass
at an optimized ratio when one wants to compost nitrogen-rich waste products,
such as manure. Recent research results have provided additional support for such
practices (Doublet et al.
2011
; Hachicha et al.
2012
; Luz Cayuela et al.
2012
; Shan
et al.
2013
; Thomas et al.
2013
). Several researchers have provided further details
of how the C:N ratio typically decreases during the course of composting, such that
the ratio often has been used as an indication of the relative maturity of compost
