(Ndegwa and Thompson 2000). In this study, vermicomposting of T 1 treatment
leads to 73.6% increase in TK content, which might be attributed to 54.4% reduction
in its organic C content. Garg et al. (2006) observed that acid production by
microorganisms is accounted for solubilization of insoluble K. Total K content in
initial cattle manure was 5.69 Æ 0.17 mg g
À1 . Irrespective of mica waste addition,
vermicomposting increased TK content in all the treatments (Fig. 13.5). During
vermicomposting, total K content was significantly (P < 0.05) increased after
40 days and kept on increasing till 50 days of vermicomposting. At the end of
vermicomposting, T 2 recorded significantly (P < 0.05) higher total K content as
compared to T 1 treatment. However, mixing of 500 g or more mica waste significantly (P < 0.05) decreased total K content in organic substrates during
vermicomposting. Vermicompost from T 4 treatment recorded the lowest total K
content, though the value was statistically at par with that of T 3 treatment.
Previously, researchers mixed chemical substrates like lime, rock phosphate, etc.
for increasing N and P contents in the final vermicompost (Pramanik et al. 2007;
Domínguez 2004). Addition of mica waste with cattle manure increased (up to
63.2%) loss of organic C during vermicomposting. Increased earthworm count
(mature and juvenile) in mica waste-amended organic substrates suggested that
earthworms preferred the combination of mica waste with organic substrates in
their feeding materials. However, addition of 10% or more (on weight basis) mica
waste with organic substrates decreased TK content in the final vermicompost as
compared to T 1 (Control) treatment. Exchangeable K and water-extractable K
contents in initial cattle manure were 2.06 Æ 0.34 and 1.22 Æ 0.10 mg g
À1 , respectively. Values of both exchangeable K and water-extractable K were significantly
(P < 0.05) increased after 20–30 days of vermicomposting (Fig. 13.5).
Vermicomposting of 500 g mica waste-added cattle manure (T 3 ) recorded the
highest EK and WEK contents, though the values were not significantly different
from those of T 2 treatment. In spite of adding 750 g mica waste in T 4 treatment,
exchangeable K and water-extractable K contents in final vermicompost did not
differ from those of T 1 treatment.
13.5 Potassium-Solubilizing Bacteria in the Gut of Epigeic
Earthworms
Suthar and Singh (2008) also reported that extractable K content in organic substrates was increased during the vermicomposting and interaction between earthworms and microorganisms plays a major role in releasing nutrients from a bound
form by degrading organic matter.
For extracting earthworm gut materials, three matured E. eugeniae earthworms,
collected from the vermin-bed, were cleaned thoroughly to remove any kind of
substance adhered to their body. Later, the specimens were kept on a moist filter
paper and allowed to starve overnight for complete gut evacuation (Dey et al. 2017).
13 Evaluating Method of Mica Waste Application in Earthworm Cast-Treated Soil for. . . 215
leads to 73.6% increase in TK content, which might be attributed to 54.4% reduction
in its organic C content. Garg et al. (2006) observed that acid production by
microorganisms is accounted for solubilization of insoluble K. Total K content in
initial cattle manure was 5.69 Æ 0.17 mg g
À1 . Irrespective of mica waste addition,
vermicomposting increased TK content in all the treatments (Fig. 13.5). During
vermicomposting, total K content was significantly (P < 0.05) increased after
40 days and kept on increasing till 50 days of vermicomposting. At the end of
vermicomposting, T 2 recorded significantly (P < 0.05) higher total K content as
compared to T 1 treatment. However, mixing of 500 g or more mica waste significantly (P < 0.05) decreased total K content in organic substrates during
vermicomposting. Vermicompost from T 4 treatment recorded the lowest total K
content, though the value was statistically at par with that of T 3 treatment.
Previously, researchers mixed chemical substrates like lime, rock phosphate, etc.
for increasing N and P contents in the final vermicompost (Pramanik et al. 2007;
Domínguez 2004). Addition of mica waste with cattle manure increased (up to
63.2%) loss of organic C during vermicomposting. Increased earthworm count
(mature and juvenile) in mica waste-amended organic substrates suggested that
earthworms preferred the combination of mica waste with organic substrates in
their feeding materials. However, addition of 10% or more (on weight basis) mica
waste with organic substrates decreased TK content in the final vermicompost as
compared to T 1 (Control) treatment. Exchangeable K and water-extractable K
contents in initial cattle manure were 2.06 Æ 0.34 and 1.22 Æ 0.10 mg g
À1 , respectively. Values of both exchangeable K and water-extractable K were significantly
(P < 0.05) increased after 20–30 days of vermicomposting (Fig. 13.5).
Vermicomposting of 500 g mica waste-added cattle manure (T 3 ) recorded the
highest EK and WEK contents, though the values were not significantly different
from those of T 2 treatment. In spite of adding 750 g mica waste in T 4 treatment,
exchangeable K and water-extractable K contents in final vermicompost did not
differ from those of T 1 treatment.
13.5 Potassium-Solubilizing Bacteria in the Gut of Epigeic
Earthworms
Suthar and Singh (2008) also reported that extractable K content in organic substrates was increased during the vermicomposting and interaction between earthworms and microorganisms plays a major role in releasing nutrients from a bound
form by degrading organic matter.
For extracting earthworm gut materials, three matured E. eugeniae earthworms,
collected from the vermin-bed, were cleaned thoroughly to remove any kind of
substance adhered to their body. Later, the specimens were kept on a moist filter
paper and allowed to starve overnight for complete gut evacuation (Dey et al. 2017).
13 Evaluating Method of Mica Waste Application in Earthworm Cast-Treated Soil for. . . 215