Agriculture Reference
In-Depth Information
Fig. 4.3
Composting of
Eichhornia crassipes
with biogas slurry
towards alkalinity was noticed and pH maxima was recorded on 8th day. This obvi-
ously is due to the fact that the optimum temperature during aerobic decomposition
and active microbial activity did not allow accumulation of the organic acids as
the inter-mediatory products and thereby, the pH of the biomass remained alkaline
in later period of decomposition. Further, interestingly low pH was observed at
mesophilic range of composting while during thermophilic range of temperature,
pH increased rapidly because of the evolution of ammonia (Kate
1990
), that during
facultative anaerobic fermentation, nitrogen in cow-dung in biogas fermenter con-
verted into ammonia. Urea considers as nitrogen fertilizer. It creates too much am-
monia for plant to absorb and provide sufficient and rapid nitrogen availability. It is
considerably metabolize by majority of urease producing bacteria, facilitate instant
nitrogen production. Wei et al. (
2012
) studied the effect of inorganic fertilizer and
composted manure amendments and found that application of composted manure
on maize was significantly more effective than that of urea. However, in another
study combined application of chemical fertilizer suggests that compost blending
increase immobilization of urea-N in soils with high C and N contents and further it
increases nitrification of fertilizer-N in soils (Han et al.
2004
). Hence, GAB mixed
with biogas slurry + urea, release ammonical form of nitrogen resulting in the rise
in pH. Moisture percentage in the GAB is another important parameter required to
be optimize for aerobic composting. At low moisture content, the decomposition
tends to be aerobic. Further, supra-optimal moisture level reduces the microbial ac-
tivity by hindering the movement of air and thus reduces the O
2
supply (Alexander
1983
). Khandelwal (
1995
) recorded that the optimum decomposition and compost
formation occur if initial moisture content is kept at 50-60 %. On further increase
in moisture content, decomposition of GAB inhibited and also impart unpleasant
odor. In-process composting of
E. crassipes
with biogas slurry is shown in Fig.
4.3
.
