Agriculture Reference
In-Depth Information
sition. During the process of biooxidation, CO
2
and N is lost and loss of
N takes place at a comparatively lower rate. Comparison of compost and
vermicompost showed that vermicompost had signifi cantly less C:N ratios
as they underwent intense decomposition (Lazcano et al. 2008).
Vermicomposting of cow manure using earthworm species
E. andrei
(Atiyeh et al. 2000b) and
E. foetida
(Hand et al. 1988) favored nitrifi ca-
tion, resulting in the rapid conversion of ammonium-nitrogen to nitrate-
nitrogen. Vermicomposting increased the concentration of nitrate-nitrogen
to 28 fold after 17 weeks, while in conventional compost there was only
3-fold increase (Subler et al. 1998; Atiyeh et al. 2000a). Increase in ash
concentration during vermicomposting suggests that vermicomposting ac-
celerates the rate of mineralization (Albanell et al. 1988). Mineralization
is the process in which the chemical compounds in the organic matter
decompose or oxidise into forms that could be easily assimilated by the
plants. Increase in ash content increases the rate of mineralization. Ash is
an alkaline substance which hinders the formation of H
2
S as well as im-
proves the availibility of O
2
and thereby renders composts odorless. Thus
vermicomposting increases the ash content and accelerates the rate of min-
eralization which is essential to make nutrients available to plants. The
observed increase of total phosphorous (TP) in vermicompost is probably
due to mineralization and mobilization of phosphorus resulting from the
enhanced phosphatase activity by microorganisms in the gut epithelium
of the earthworms (Zhang et al. 2000; Garg et al. 2006). Vermicomposts
showed a signifi cant increase in exchangeable Ca
2+
, Mg
2+
and K
+
com-
pared to fresh sludge indicating the conversion of nutrients to plant-avail-
able forms during passage through the earthworm gut (Garg et al. 2006;
Yasir et al. 2009a). Vermicomposts contain higher nutrient concentrations,
but less likely to produce salinity, than composts. Additionally, vermicom-
posts possess outstanding biological properties and have microbial popu-
lations signifi cantly larger and more diverse compared to conventional
composts (Edwards 1998). Soil supplemented with vermicompost showed
better plant growth compared to soil treated with inorganic fertilizers or
cattle manure (Kalembasa 1996; Subler et al. 1998).
