compound after the digestion of organic matter as a food product, and these minerals
get accumulated in the final substrate (Deka et al. 2011).
The carbon mineralization or total organic carbon (TOC) is an important indicator
of waste stabilization (Suthar 2012). Various kinds of biodegradable wastes have
lower TOC, but there is 20–45% reduction of TOC in the form of CO 2 during
vermiconversion of industrial or municipal wastes (Kaviraj and Sharma 2003)
because earthworms promote biochemical degradation and their activity led to
colonization of communities of decomposers in the waste. Dominguez and Edwards
(2004) asserted that the material ingested by earthworms was fragmented and
homogenized by the muscular action of their foregut that added mucus and enzymes
to the material, which was ingested by increasing the surface area for the action of
microbes, while the microorganisms brought about the degradation of wastes in the
worm’s gut by providing some extra cellular enzymes. During this process, the
substrate material was modified by the earthworms by losing carbon through microbial respiration in the form of carbon dioxide (Aira et al. 2007). Suthar (2010)
described that the inoculated earthworms in substrate material digest the carbohydrates and some other polysaccharides, which causes reduction in carbon which may
be due to conversion of organic carbon to worm biomass through assimilation
process that further led to reduction of carbon budget of substrate material during
vermicomposting of organic waste.
Earthworms play significant role in improving and enhancing the nitrogen content (N) of the substrate (Muthukumaravel et al. 2008). The elevation in nitrogen
content is due to the action of N-fixing bacteria and mineralization of C-rich
materials as well as low pH that helps in nitrogen retention, as at higher pH it may
be lost as ammonia (Plaza et al. 2007). The nitrogen in vermicompost is dependent
on two factors:
1. Nitrogen content present in the initial substrate material
2. Rate of decomposition process
The N content was enhanced due to the addition of nitrogenous substances,
mucus, growth-stimulating hormones, and enzymes during digestion and fragmentation of organic matter by the earthworms (Varma et al. 2015). Even the loss of
organic carbon content, conversion of ammonium nitrogen into nitrate, and mineralization of the organic matter containing proteins may also play an important role in
the increase of nitrogen content in vermicompost (Yadav and Garg 2011b). Earthworms also promote the decomposition of organic materials that accelerates the
mineralization process of nitrogen and leads to change in nitrogen profile of the
substrate (Benitez et al. 1999).
Phosphorus (P) plays a significant role in plant physiology as it is essentially
required for the process of photosynthesis and other metabolic pathways of plant, so
it is formed by the P-mineralization process in vermibeds during vermicomposting
(Suthar 2012). The small amount of phosphorus is converted to more available forms
by the action of gut enzymes of earthworm, that is, alkaline phosphatases and acid
phosphatases, which makes it more available to plants during vermiconversion
process (Swarnam et al. 2016). Even the actions of phosphorus-solubilizing
15 Waste Management Practices and Their Impact on Earthworms
251
get accumulated in the final substrate (Deka et al. 2011).
The carbon mineralization or total organic carbon (TOC) is an important indicator
of waste stabilization (Suthar 2012). Various kinds of biodegradable wastes have
lower TOC, but there is 20–45% reduction of TOC in the form of CO 2 during
vermiconversion of industrial or municipal wastes (Kaviraj and Sharma 2003)
because earthworms promote biochemical degradation and their activity led to
colonization of communities of decomposers in the waste. Dominguez and Edwards
(2004) asserted that the material ingested by earthworms was fragmented and
homogenized by the muscular action of their foregut that added mucus and enzymes
to the material, which was ingested by increasing the surface area for the action of
microbes, while the microorganisms brought about the degradation of wastes in the
worm’s gut by providing some extra cellular enzymes. During this process, the
substrate material was modified by the earthworms by losing carbon through microbial respiration in the form of carbon dioxide (Aira et al. 2007). Suthar (2010)
described that the inoculated earthworms in substrate material digest the carbohydrates and some other polysaccharides, which causes reduction in carbon which may
be due to conversion of organic carbon to worm biomass through assimilation
process that further led to reduction of carbon budget of substrate material during
vermicomposting of organic waste.
Earthworms play significant role in improving and enhancing the nitrogen content (N) of the substrate (Muthukumaravel et al. 2008). The elevation in nitrogen
content is due to the action of N-fixing bacteria and mineralization of C-rich
materials as well as low pH that helps in nitrogen retention, as at higher pH it may
be lost as ammonia (Plaza et al. 2007). The nitrogen in vermicompost is dependent
on two factors:
1. Nitrogen content present in the initial substrate material
2. Rate of decomposition process
The N content was enhanced due to the addition of nitrogenous substances,
mucus, growth-stimulating hormones, and enzymes during digestion and fragmentation of organic matter by the earthworms (Varma et al. 2015). Even the loss of
organic carbon content, conversion of ammonium nitrogen into nitrate, and mineralization of the organic matter containing proteins may also play an important role in
the increase of nitrogen content in vermicompost (Yadav and Garg 2011b). Earthworms also promote the decomposition of organic materials that accelerates the
mineralization process of nitrogen and leads to change in nitrogen profile of the
substrate (Benitez et al. 1999).
Phosphorus (P) plays a significant role in plant physiology as it is essentially
required for the process of photosynthesis and other metabolic pathways of plant, so
it is formed by the P-mineralization process in vermibeds during vermicomposting
(Suthar 2012). The small amount of phosphorus is converted to more available forms
by the action of gut enzymes of earthworm, that is, alkaline phosphatases and acid
phosphatases, which makes it more available to plants during vermiconversion
process (Swarnam et al. 2016). Even the actions of phosphorus-solubilizing
15 Waste Management Practices and Their Impact on Earthworms
251