Agriculture Reference
In-Depth Information
vermicomposting as a cottage industry in this country, where there is no dearth of organic wastes
or labor. The tapping of a resourceful technology is of utmost importance for the present day
because Ñsoil is the placenta of life.Ò
HUMUS PRODUCED BY EARTHWORM ACTIVITY:
ORGANIC WASTE TO SOIL
Joshi and Kelkar (1952) reported higher electrical conductivity in earthworm casts, which denotes
an increase in the levels of soluble salts over the surrounding soil. They showed that casts have
greater nitrifying power than the soil. Earthworm casts, as aggregates, make the site more aerobic.
The stability of the casts depends on the concentration and type of organic matter present and the
bacterial and fungal polysaccharides (Dutt 1948; Bhandari et al. 1967). Earthworm casts are better
sources of organic manure than other anaerobically degraded composts because of the factors
discussed in this section.
Casts are loosely packed granular aggregates of semidigested organic matter that provide energy
for the establishment and multiplication of various microorganisms. Some of the microorganisms
associated with the casts remove the bad odor from decomposing materials (Watanabe et al. 1982).
The casts also form a suitable base for free-living beneficial microorganisms with activity that is
essential for the release of nutrients to plants (Atlavinyte and Daciulyte 1969; Atlavinyte and
Vanagas 1982; Ross and Cairns 1982). The establishment of a microenvironment takes place in
the presence of earthworms in the given medium (Kale et al. 1987). Especially in tropical countries,
earthworms cannot remain active throughout the whole year (Roy 1957; Reddy and Alfred 1978;
Chauhan 1980). Nutrients from the soil leach out at a rapid rate under ambient soil and environ-
mental conditions in tropical countries, particularly during monsoons. Under such circumstances,
the application of earthworm casts or vermicomposts to fields can improve the physicochemical
and biological properties of the soil (Kale et al. 1992).
The biochemical activity of established microorganisms and earthworm exudates has a stimu-
latory effect on plant growth (Ross and Cairns 1982). The presence of earthworms in culture pots
improved the germination, growth, and yield of a barley crop (Atlavinyte and Zimkuviene 1985).
A higher level of vitamin B
in the medium because of earthworm activity was reported by
Atlavinyte and Daciulyte (1969). Nielson (1965) isolated indole acetic acid (IAA)Ïlike substances
from homogenates of different species of earthworms. Springett and Syers (1979) reported increases
in net crop production after application of earthworm casts. Similar information is available on
improvements in the growth and yields of crops influenced by earthworm exudates (Graff and
Makeschin 1980).
Tomati et al. (1990) reported on the presence of growth regulator substances in earthworm-
worked soils. Increases in the protein synthesis of
12
Agaricus bisporus
and radish
Raphanus sativam
was recorded in plants grown in the presence of earthworm casts (Galli et al. 1990; Tomati et al.
1990). Increase in the rates of uptake of nutrients with the increase in symbiotic microbial associ-
ations in cereal and ornamental plants after using vermicompost as a source of organic manure
were observed (Kale et al. 1987, 1992). Similarly, in a perennial crop such as mulberry, there was
no difference in the uptake of nutrients in plants grown with vermicomposts or chemical fertilizers.
Although the NPK concentrations applied to land in the form of chemicals was higher than the
level of the same components in vermicompost, the level that entered the plant tissues remained
the same irrespective of the concentrations that entered the soil (Gunatrilakara and Ravignanami
1996). Karuna et al. (1999) observed improved growth and increased flower blooms in tissue-
cultured crinkle red variety of
Anthurium andreanum
Lind. on using earthworm body fluid (ver-
miwash) as a spray against the urea-sprayed plants.
