Agriculture Reference
In-Depth Information
carbon (C) sequestration and reduction of CO
2
released through mineralization
(Lhadi et al.
2006
). Compost is usually used as a soil improver through the enrich-
ment of stable organic matter; compost application into soil is invaluable measure
for C sequestration in soil as it contains stable organic matter that helps accumu-
late soil organic C (SOC) in short term (Adani et al.
2009
). It is worth to note that
soil degradation by organic matter depletion together with land-use change are the
major reasons for CO
2
emission from agricultural activities that contributed 33 %
of CO
2
increase among the other anthropogenic emissions (about 28 % increase)
(IPCC
2000
,
2001
).
1.2.2
A Plethora of Compost
Compost is one term that is used to describe millions of composts that are different
in quality parameters, starting mixture and composting technological solutions. So
far, it is possible to use either the term 'compost' or to address the term 'compost-
ing' at an aerobic maturation process of organic substrates in a plenty of cases and
circumstances: (i) different raw materials available to start the process, (ii) their state
of conservation; (iii) their pre-treatments e.g., shredding, size and age, (iv) their
relative percentages in the starting mixture, (v) inclusion or exclusion of inocula,
(vi) the structuring material (source, size and amount), (vii) the technologies used
to mix, to aerate, to keep the right moisture content, (viii) the days of process, and
(ix) the control procedures, the most important variable, which are able to affect in
a relevant way the characteristics of the final products of any composting process.
At the end, the product will be named compost in any case but its final characteris-
tics (physical, chemical and biological) will vary in a vast range. Materials used for
composting varies largely and consequently their microbial loads and their changes
during the composting process, which leads to different final ready-to-use composts.
Judging these final products through unique parameter might not give the best in-
dication or characterization but a set of representative parameters should be used to
characterize and categorize final compost. These parameters might include total or-
ganic C, pH, total nitrogen (N) and germination index (Campitelli and Ceppi
2008
).
1.2.3
Regulatory Framework for Industrial Compost
At industrial facilities level, the compost product can go on the market as commer-
cial 'compost' only under the observance of national law. The situation differs from
country to another but it is possible to summarize it into two sets of parameters:
(i) in case of heavy metals (Cu, Zn, Hg, Cd, Pb, Cr, Ni), pH, unfavorable bacteria
(Enterobacteriaceae, Faecal Coliform,
Streptococcus
and
Salmonella
), Protozoa,
eggs of Platyhelminthes, eggs of Nematodes and inertia (plastic, glass, stone), these
parameters must be below specific thresholds fixed for each parameter; (ii) in case
of organic matter content, humic and fulvic acids and organic N percentage over to-
tal N amount they must be above the fixed thresholds. Nevertheless, some countries
