MSc

A field experiment was conducted at the Agricultural Research Station,
Mannuthy in summer rice fallow during January-April, 1997. The study was to
assess the effect of tillage practices and use of agrochemicals on soil V AM and to
analyse the possibility of any saving in inorganic fertilizer use. Effect of summer
cropping on improvement of soil health was also aimed at.
The experiment was laid out in strip plot design with 24 treatment
combinations replicated thrice. Combination of tillage and herbicide levels were
tried in parallel strips. Fertilizer levels were given across these strips. Tillage levels
included minimum and normal tillage. Fertilizer levels consisted of control, full
recommended doze of fertilizer i.e., inorganics and organics, half the recommended
doze of fertilizer i.e., inorganics and organics, half the recommended doze of
fertilizer i.e., inorganics and organics along with VAM, full recommended dose of
inorganics alone and full recommended doze of organics alone.
Results revealed that most of the growth characters were not significantly
influenced by tillage treatments. However, with respect to plant height and
drymatter production higher values were observed in minimum tilled plots. Yield
attributing characters favourably influenced by minimum tillage were number of
pods per plant, weight of pods per plant, test weight, pod yield per ha, grain yield
per ha and stover yield per ha. Nitrogen and phosphorus uptake were favoured by
minimum tillage. Organic carbon status, available nitrogen and available zinc were
higher in minimum tilled plots.


Most of the growth and yield attributing characters were not affected by
herbicide application. Soil studies revealed slightly lower values for organic carbon,
available nitrogen and available phosphorus content in herbicide applied plants.
Fertilizer levels had more significant influence on yield attributes and soil
nutrient levels. In all the growth characters half of the recommended doze of
fertilizer along with V AM was superior or equally well as that of full recommended
doze of fertilizer and full organics alone. The same combination fared well with
most of the yield characters also.
Among the interaction effects tillage x fertilizer interactions were
significant in percentage nitrogen in plant, protein content of grain, organic carbon
status and available potassium in soil. Herbicide-fertilizer interactions were
significant in the case of percentage nitrogen, uptake of nitrogen, percentage
phosphorus in plant, organic carbon status of soil and available potassium of soil.
Tillage and herbicide interactions significantly influenced only on organic carbon
status of soil.
To conclude, minimum soil disturbance was prefered in summer
cropping. The use of agrochemicals especially herbicide (Alachlor) in the normal
recommended doze of 2.5 kg ai/ha was rather safe on V AM population in soil.
Integrated nutrient management comprising of the use of organics, inorganics and
bioinoculant was more cost effective and desirable in terms of crop performance
and improvement in soil health.