18.6.3 Soil Biological Properties
Biological indicators, especially assessment of microbial activity and biomass, are
sensitive to soil management practices. As a result, any changes in these properties
may precede detectable changes in other soil properties (chemical and physical
properties), thus providing early signal of improvement or warning of degradation
(Gomez et al. 2006; Diacono and Montemurro 2010). Vermicasts generally contain
enormous quantitiesof bacteria, actinomycetes and fungi. The increased population
can possibly be attributed to increased surface area for microbial activity as a result
of organic matter fragmentation within the earthworm’s gizzard. Vermicompost is
also a source of organic matter, which is a food source for beneficial soil microbes,
and it aids in improving microbial population and diversity. The enhanced beneficial
microbial diversity influences transformation, release and cycling of essential nutrients (Sinha and Herat 2012; Soni and Sharma 2016). Indicators of soil microbiological activity include biomass C, basal respiration, ratio of biomass C to total
organic C, enzyme activity and metabolic quotients (Arancon et al. 2006). A
comparative study was conducted by Arancon et al. (2006) between vermicompost
and inorganically fertilized soils with the application of food waste vermicompost,
resulting in significantly greater dehydrogenase activity and microbial N relative to
the soils with inorganic fertilizer.
18.7 Crop Responses to Vermicomposts and Other Organic
Fertilizers
Vermicomposts, whether used as soil amendments or as component of plant growing
media, have the ability to improve seed germination, enhance seedling growth,
development and overall plant productivity (Peyvast et al. 2007). Positive results
have been reported on both media quality and crop development, where
vermicomposts were used as a combination of artificial media (Atiyeh et al. 2001;
Arancon et al. 2006). The increased growth and yield are attributed to the improved
soil or media properties such as increased nutrient availability for plant uptake,
microbial activity and plant growth regulators, which are produced by activity of
microorganisms such as fungi, bacteria and actinomycetes (Singh et al. 2008;
Azarmi et al. 2008). It is noteworthy that addition of vermicompost in soils does
not only improve activity of beneficial microorganisms but it also suppresses growth
disease causing microorganisms and population of plant parasitic nematodes (Singh
et al. 2008). Plant growth is also enhanced by the ability of the vermicompost to
supply essential plant nutrients when required. Vermicompost provides a large
particulate surface area that provides microsites for strong retention of nutrients in
the soil (Singh et al. 2013).
Kumari and Ushakumari (2002) used a rock phosphate enriched vermicompost to
amend a soil planted with cow peas (Vigna unguiculata) and evaluated yield and
18 Some Perspectives on Vermicompost Utilization in Organic Agriculture
319
Biological indicators, especially assessment of microbial activity and biomass, are
sensitive to soil management practices. As a result, any changes in these properties
may precede detectable changes in other soil properties (chemical and physical
properties), thus providing early signal of improvement or warning of degradation
(Gomez et al. 2006; Diacono and Montemurro 2010). Vermicasts generally contain
enormous quantitiesof bacteria, actinomycetes and fungi. The increased population
can possibly be attributed to increased surface area for microbial activity as a result
of organic matter fragmentation within the earthworm’s gizzard. Vermicompost is
also a source of organic matter, which is a food source for beneficial soil microbes,
and it aids in improving microbial population and diversity. The enhanced beneficial
microbial diversity influences transformation, release and cycling of essential nutrients (Sinha and Herat 2012; Soni and Sharma 2016). Indicators of soil microbiological activity include biomass C, basal respiration, ratio of biomass C to total
organic C, enzyme activity and metabolic quotients (Arancon et al. 2006). A
comparative study was conducted by Arancon et al. (2006) between vermicompost
and inorganically fertilized soils with the application of food waste vermicompost,
resulting in significantly greater dehydrogenase activity and microbial N relative to
the soils with inorganic fertilizer.
18.7 Crop Responses to Vermicomposts and Other Organic
Fertilizers
Vermicomposts, whether used as soil amendments or as component of plant growing
media, have the ability to improve seed germination, enhance seedling growth,
development and overall plant productivity (Peyvast et al. 2007). Positive results
have been reported on both media quality and crop development, where
vermicomposts were used as a combination of artificial media (Atiyeh et al. 2001;
Arancon et al. 2006). The increased growth and yield are attributed to the improved
soil or media properties such as increased nutrient availability for plant uptake,
microbial activity and plant growth regulators, which are produced by activity of
microorganisms such as fungi, bacteria and actinomycetes (Singh et al. 2008;
Azarmi et al. 2008). It is noteworthy that addition of vermicompost in soils does
not only improve activity of beneficial microorganisms but it also suppresses growth
disease causing microorganisms and population of plant parasitic nematodes (Singh
et al. 2008). Plant growth is also enhanced by the ability of the vermicompost to
supply essential plant nutrients when required. Vermicompost provides a large
particulate surface area that provides microsites for strong retention of nutrients in
the soil (Singh et al. 2013).
Kumari and Ushakumari (2002) used a rock phosphate enriched vermicompost to
amend a soil planted with cow peas (Vigna unguiculata) and evaluated yield and
18 Some Perspectives on Vermicompost Utilization in Organic Agriculture
319