13.6 Application of Vermicompost in Soil
Vermicompost has a good balance of major plant nutrients in an organically bound
form and in an inorganic plant-available form. Hence, application of vermicompost
as an organic amendment supplies sufficient nutrients to support plant growth, and it
also builds up reserve pool of nutrients in soil. Pramanik et al. (2010) revealed that
applied organic matter through vermicompost increased the activity of several
important enzymes, viz. phosphatase, urease, etc., in soil. Hence, vermicompost
application further increases the availability of major nutrients like nitrogen and
phosphorus in soil (Pramanik et al. 2007). However, sustaining potassium availability is a major challenge in vermicompost-treated soil.
Vermicompost application also has a positive impact on microbial community in
soil. Microbial activity, determined by quantifying carbon dioxide emission from
soil, is significantly increased by vermicompost application and that in turn was
attributed to increased population of all groups of soil microorganism, viz. bacteria
(both Gram-positive and Gram-negative) and fungi (Pramanik et al. 2012). Microorganisms of all specific groups like nitrifying bacteria, phosphate-solubilizing
microorganisms and potassium-solubilizing bacteria show higher population in
vermicompost-treated soil as compared to untreated control soil. Hence, higher
potassium-solubilizing bacterial population could be exploited by mixing mica
waste along with vermicompost to enhance and sustain potassium availability in
vermicompost-treated soil.
13.7 Application of Mica Waste and Vermicompost in Soil
Application of mica waste is an alternative method to supplement K in soil. Mica
waste is a slow K-releasing mineral, which possesses K atoms in the interlayer space
of two expandable octahedral lattices. Humic substrates facilitate K release from
mica waste by distorting its crystal structure. Since vermicompost contains up to 5%
humic substrates, combined application of mica waste and vermicompost is expected
to enhance K availability in soil.
An experiment was conducted in the net house of the Tocklai Tea Research
Institute (TTRI) (26
41
00 N and 94
43
00 E), Tea Research Association, Jorhat, Assam,
India, to evaluate the effect of mica waste and vermicompost on K availability in soil
and on plant growth. A virgin soil, collected from Borbetta Tea Estate, was used for
this experiment. This soil was sandy clay loam in texture and had pH 5.11 Æ 0.27,
total organic carbon 0.92 Æ 0.06 g kg
À1 and exchangeable K content
108.33 Æ 16.47 mg kg
À1 . Six-month-old tea plants (Tocklai Vegetative (TV)—23
cultivars) were transplanted in pot soil (6.5 kg), and after 1 week of acclimatization,
total six treatments were applied in soil. The treatment details are mentioned in
Table 13.1. Here, the doses of soil amendments were considered following recommendations of tea-growing soil. Nylon net of the net house restricts about 70% of the
13 Evaluating Method of Mica Waste Application in Earthworm Cast-Treated Soil for. . . 219
Vermicompost has a good balance of major plant nutrients in an organically bound
form and in an inorganic plant-available form. Hence, application of vermicompost
as an organic amendment supplies sufficient nutrients to support plant growth, and it
also builds up reserve pool of nutrients in soil. Pramanik et al. (2010) revealed that
applied organic matter through vermicompost increased the activity of several
important enzymes, viz. phosphatase, urease, etc., in soil. Hence, vermicompost
application further increases the availability of major nutrients like nitrogen and
phosphorus in soil (Pramanik et al. 2007). However, sustaining potassium availability is a major challenge in vermicompost-treated soil.
Vermicompost application also has a positive impact on microbial community in
soil. Microbial activity, determined by quantifying carbon dioxide emission from
soil, is significantly increased by vermicompost application and that in turn was
attributed to increased population of all groups of soil microorganism, viz. bacteria
(both Gram-positive and Gram-negative) and fungi (Pramanik et al. 2012). Microorganisms of all specific groups like nitrifying bacteria, phosphate-solubilizing
microorganisms and potassium-solubilizing bacteria show higher population in
vermicompost-treated soil as compared to untreated control soil. Hence, higher
potassium-solubilizing bacterial population could be exploited by mixing mica
waste along with vermicompost to enhance and sustain potassium availability in
vermicompost-treated soil.
13.7 Application of Mica Waste and Vermicompost in Soil
Application of mica waste is an alternative method to supplement K in soil. Mica
waste is a slow K-releasing mineral, which possesses K atoms in the interlayer space
of two expandable octahedral lattices. Humic substrates facilitate K release from
mica waste by distorting its crystal structure. Since vermicompost contains up to 5%
humic substrates, combined application of mica waste and vermicompost is expected
to enhance K availability in soil.
An experiment was conducted in the net house of the Tocklai Tea Research
Institute (TTRI) (26
41
00 N and 94
43
00 E), Tea Research Association, Jorhat, Assam,
India, to evaluate the effect of mica waste and vermicompost on K availability in soil
and on plant growth. A virgin soil, collected from Borbetta Tea Estate, was used for
this experiment. This soil was sandy clay loam in texture and had pH 5.11 Æ 0.27,
total organic carbon 0.92 Æ 0.06 g kg
À1 and exchangeable K content
108.33 Æ 16.47 mg kg
À1 . Six-month-old tea plants (Tocklai Vegetative (TV)—23
cultivars) were transplanted in pot soil (6.5 kg), and after 1 week of acclimatization,
total six treatments were applied in soil. The treatment details are mentioned in
Table 13.1. Here, the doses of soil amendments were considered following recommendations of tea-growing soil. Nylon net of the net house restricts about 70% of the
13 Evaluating Method of Mica Waste Application in Earthworm Cast-Treated Soil for. . . 219