MSc

The study entitled "Effect of vermicompost on the electrochemical properties and
nutritional characteristics of variable charge soils" has been carried out during 1994-95
which comprised of two experiments, viz., an incubation study and a pot culture
experiment.
The incubation experiment was carried out at the laboratory attached to the
Department of Soil Science and Agrl. Chemistry, College of Agriculture, Vellayani
which was intended to study the effect of vermicompost (VC) in comparison with two
other organic manures, viz., FYM and ordinary compost, on the electro-chemical
properties and nutritional characteristics of a low activity clay soil taken from
Vellayani. The pot culture experiment was conducted using the same soil used for the
incubation study, to compare the agronomic effectiveness of various organic manures
including vermicompost using cowpea as a test crop.
Both the experiments were laid out in Completely Randomized Design. The
incubation experiment was conducted with nine treatments consisting of various
organic manures with and without rock phosphate. Periodical sampling and analyses of
soil incubated with various treatment materials were done at 30 days' interval to study
the comparative effect of treatments on the electo-chemical properties and nutritional
characteristics of the soil.
The pot culture experiment was conducted with eleven treatments containing
different organic manures with and without chemical fertilizers, to study the
comparative effect of different treatments on crop growth using cowpea.
Observations on various biometric and yield parameters have been recorded and
analyses of plant samples were done at three stages of growth of the plant, viz., 20
DAS, maximum flowering and at harvest. The nutrient status of the soil after the
experiment was also analysed.
From the incubation experiment it was made clear that the effect of various
organic manures differed significantly in influencing the electro-chemical and
nutritional properties of variable charge soils.
In general, vermicompost maintained its superiority over other organic
manures, especially in the presence of chemical fertilizers, in influencing various soil


properties. The effects were statistically significant in the order vermicompost >
FYM> ordinary compost.
From the experiment it was proved that lower doses of vermicompost could be
equated with higher doses of FYM and ordinary compost. Vermicompost established
its superiority over other organic manures by influencing many of the soil properties
favourably. The major effects were the reduction in P-fixation and increased P
solubility in presence of vermicompost. The increased mineralisation of other major
and secondary nutrients in the presence of VC caused an enhancement in the
availability of these nutrients on an equivalent weight basis. A substantial increase in
base status and pH, caused by vermicompost improved the overall plant nutrient status
and soil environment compared to other organic manures. The organic matter
fractions and other colloidal fractions were found to be favourably influenced by
vermicompost. Organic colloids, being the most active and reactive phase of the soil,
its contribution towards the total base exchange capacity and cation protection was
more pronounced in the case of vermicompost.
Biometric observations at critical stages of growth of the crop and yield
parameters recorded when analysed statistically have proved the superiority of VC
over other organic amendments studied. Vermicompost application in combination
with chemical fertilizers was proved to be the best among treatments tested. Lower
doses of VC (10 t ha-1) with lime and fertilizers was equally effective as higher doses
(20 t ha-1) of other organic manures studied. Analysis of plant samples at critical
stages of growth also revealed the same effect. Soil analysis data after the pot
experiment has further established the superiority of VC over other treatments. This is
indicative of the ability of VC to sustain a higher level of soil fertility for a sufficiently
longer period of time.
However, the present study being an experiment under controlled conditions,
further research involving detailed field experimentation with selected crops is needed
for drawing final conclusions.