Agriculture Reference
In-Depth Information
microbial population combining both mesophilic and thermophilic activities, leading
to the production of carbon dioxide, water, minerals and stabilized organic matter
(Pereira-Neta 1987 ). Composting is one of the most effective means of recycling of
organic wastes that can be used as a source of soil amendment and organic matter
in agricultural land. The variability of the organic matter undergoing composting
makes compost research challenging. In recent years, interest in composting has
increased because of the social demand for an environmentally friendly waste treat-
ment technology and for organic agricultural products. Composting is seen as not
only an environmentally acceptable method of waste treatment, but also one of the
more efficient methods of waste disposal which enables recycling of organic mat-
ter (Ko et al. 2008 ). The application of composted manure has increased over the
years. This practice improves the quality of the crops and preserves the environment
(Hoitink 2000 ; Ko et al. 2008 ). However, non-composted manure may have adverse
effects on plant growth and/or seed germination (Hoekstra et al. 2002 ) because of
their wide C:N ratio and production of phytotoxic substances such as phenolic and
volatile fatty acids during organic matter decomposition (Kirchmann and Widen
1994 ). Mesophilic and thermophilic micro-organisms are involved in the composting
and their succession is important in the effective management of composting process
(Ishii et al. 2000 ). Many studies have shown that the composting process eliminates
or reduces the risk of spreading of pathogens, parasites and weed seeds associated
with direct land application of immature compost and leads to final stabilized product
(Larney and Hao 2007 ; Bernal et al. 2009 ). The need to treat and dispose of organic
wastes to reduce potential damage has made compost production and its agricultural
application an attractive solution. The composting industry is poised for a new era
of growth where the product must be evaluated both for safety and quality purposes.
Composts prepared from different organic wastes differ in their quality, which further
depends upon the composition of raw material and composting technology used for
compost production (Ranalli et al. 2001 ). Quality of high grade compost generally
relates to its fertilizer value. If unstable or immature compost is applied, it can induce
anaerobic conditions as the micro-organisms utilize oxygen in the soil pores to break
down the material (Mathur et al. 1993 ). Another problem associated with immature
compost is the phytotoxicity due to the presence of organic acids during early stages
of the composting process (Fuchs 2002 ; Cambardella et al. 2003 ). Compost quality is
closely related to its stability and maturity. Maturity is associated with plant-growth
potential or phytotoxicity (Iannotti et al. 1994 ), whereas stability is often related with
the compost's microbial activity. However, both stability and maturity usually go
hand in hand, since phytotoxic compounds are produces by the micro-organisms in
unstable composts (Zucconi et al. 1985 ). Several parameters have been proposed for
evaluating compost maturity and stability (Iglesias Jiménez and Pérez García 1992 ;
Wu et al. 2000 ; Bernal et al. 2009 ; Raj and Antil 2011 ; Antil et al. 2012 ). However,
there is no single method that can be universally applied to all types of compost due to
variation of materials and composting technology (He et al. 1995 ; Benito et al. 2003 ;
Chang and Chen 2010 ). Morel et al. ( 1985 ) proposed that the maturity of the compost
may be assesses by the biological activity of the product, including total microor-
ganisms count, monitoring biochemical parameters of microbial activity and analy-
sis of biodegradable constituents. The changes in microbial properties during the
Search WWH ::




Custom Search