MSc

The research entitled "Effect of integrated plant nutrient system (IPNS) on
the soil biological regimes in red loam' soil" was a study undertaken in the
Dept. of Soil Science and Agrl. Chemistry during the period from March 2012
to June 2012. The objective of the study was to assess the conjugal effect of
manures and chemical fertilizers on dynamics of major agriculturally
significant soil enzymes, available nutrient status of the soil, its relation with
the activities of major soil enzymes, soil micro flora, yield and yield attributes
of the test crop and computation of Biological Fertility Index through Enzyme
Activity Number.
Field experiment using bhindi as test crop consisted of 15 treatments. The
treatments were laid out in RBD with three replications. The treatments were
T1_ Package of practice recommendation (KAU), T2 _ N (25 %) as neem cake
enriched vermicompost + N (75%), P & K, T3 _ N (25 %) as Azospirillum
enriched vermicompost + N (75%), P & K, T4 _ P (25 %) as PSB enriched
vermicompost + P (75%), N & K, T5- NPK (25 %) as PGPR mix-1 enriched
vermicompost + N, P & K (75%), T6- N (50%) as Neem cake enriched
vermicompost+ N (50%), P & K, T7- N (50%) as Azospirillum enriched
vermicompost + N (50%), P & K, Ts- P (50 %) as PSB enriched
vermicompost + P (50%), N & K, T9 _ NPK (50 %) as PGPR mix-1 enriched
vermicompost + N, P & K (50%), TlO. N (75 %) as Neem cake enriched
vermicompost + N (25%),P & K, T11_ N (75 %) as Azospirillum enriched
vermicompost + N (25%), P & K , T12- P (75%) as PSB enriched
vermicompost + P (25%), N & K, TJ3_,N, P, K, (75 %) as PGPR mix-1
enriched vermicompost + N, P & K (25%), T14- N, P, K alone as inorganics,
T 15- Absolute control

Results revealed that maximum available N content and urease activity in
rhizosphere soil were recorded with the treatment T n- Treatment T 9 increased
available micro nutrient status (Fe, Cu, B), biological properties of soil viz.,
dehydrogenase, cellulase and protease activities; and biometric characters of
bhindi i.e., plant height and no. of fruits. Results showed significant variations
in electrical conductivity, phosphatase activity and bacterial count and
advancement of flowering days with the application of treatment Ts. The
highest available K, actinomycetes and yield attributes including yield per ha
and yield per plant was noticed with the application of treatment T 13.
V max and Km for each enzyme at fortnightly intervals were recorded after the
imposition of each treatment. Highest V max values for urease, phosphatase,
protease, dehydrogenase and cellulase were recorded at 6th week, 6th week, 8th
week, 2nd week and 6th week respectively. Km values for urease was highest at
eighth week, phosphatase at sixth week, protease at eighth week,
dehydrogenase at second week and cellulase at sixth week. Comparison of
biological properties such as enzyme activities and microflora between
rhizosphere and non-rhizosphere soils had shown variation highlighting the
rhizosphere effect in the test crop. A highest value of Enzyme Activity
Number, which is an index of biological fertility, was registered by the
treatment T 9, revealing its superiority over other treatments.
Conclusion
Treatment T9 with the application ofNPK (50 %), PGPR mix-l enriched
vermicompost + N,' P & K (50%) was found to be the best treatment both in
sustaining soil biological fertility and economic returns. The treatment has
recorded highest values for Enzyme activity number as well as for B: C ratio.