impact of farmers' organic farming practices on soil properties in ...

VI. SUMMARY
A study was conducted in the Northern Dry Zone <strong>of</strong> Karnataka to know the effect <strong>of</strong>
farmers’ <strong>practices</strong> in <strong>organic</strong> <strong>farming</strong> on soil properties and soil health in selected major
cropping systems.
The soil samples were collected and analysed for soil physical, chemical and
biological properties and also for availability <strong>of</strong> plant nutrients. The salient findings <strong>of</strong> the
investigation are summarized in this chapter.
Farmyard manure and vermicompost were the sources <strong>of</strong> <strong>organic</strong>s used by <strong>organic</strong>
farmers in the study area. The quantity <strong>of</strong> <strong>organic</strong>s applied to soils varied from 8.0 to 20.0
tonnes <strong>of</strong> FYM per ha per year and 1.0 to 3.0 tonnes <strong>of</strong> vermicompost per ha per year.
The nutrient (N, P and K) concentration was higher in vermicomposts than in FYM. The
C:N ratio <strong>of</strong> vermicomposts was also narrower in vermicomposts (13:1 to 20:1) compared
to its ratio in FYM (25:1 to 38:1).
The quality <strong>of</strong> nutrients added to soil through <strong>organic</strong>s varied widely depending upon the
nutrient concentration and quantity <strong>of</strong> <strong>organic</strong>s applied by the farmer.
The physical properties <strong>of</strong> soils were found to be influenced favourably by the <strong>organic</strong>
<strong>farming</strong> practice. A reduction in bulk density and an increase in water holding capacity
and water stable aggregates was noticed in all the soils under <strong>organic</strong> <strong>farming</strong>.
A reduction in pH was observed in soils under <strong>organic</strong> <strong>farming</strong>. But, however there was
no appreciable change in the EC <strong>of</strong> soils.
A wide variation in increase in <strong>organic</strong> carbon content (19.42% to 102.94%) <strong>of</strong> soils <strong>of</strong>
<strong>organic</strong> farms over conventional farms was observed. The soils under <strong>organic</strong> farms also
recorded higher CEC values than those under conventional farms and the increase was
between 5.40 to 16.60 per cent.
The soils under <strong>organic</strong> <strong>farming</strong> recorded higher amounts <strong>of</strong> available N, P, K and S than
the soils under conventional <strong>farming</strong>.
The average increase in available nitrogen and phosphorus in soils <strong>of</strong> <strong>organic</strong> farms over
conventional farms ranged from 7.27 per cent and 6.85 per cent to 15.20 per cent and
23.80 per cent, respectively.
The available potassium content increased marginally (2 – 5%) in the soils under <strong>organic</strong>
<strong>farming</strong>.
The available sulphur in soils, on an average, increased from 3.60 per cent (kharif jowar
based cropping system) to 10.40 per cent (cotton based cropping system) due to <strong>organic</strong>
<strong>farming</strong> practice.
All the soils irrespective <strong>of</strong> type <strong>of</strong> <strong>farming</strong> and cropping system contained DTPAextractable
micronutrients above the critical concentration, with soils under <strong>organic</strong>
<strong>farming</strong> recording comparatively higher amounts than those under conventional <strong>farming</strong>.
A substantial increase in available status <strong>of</strong> Zn, Fe, Mn and Cu in soils <strong>of</strong> <strong>organic</strong> farms
was observed.
A marked increase in dehydrogenase activity was observed in the soils <strong>of</strong> <strong>organic</strong> farms
in all the cropping systems.
From the study, it could be concluded that the soil properties get favourably
influenced by <strong>organic</strong> <strong>farming</strong> practice which in turn would enhance the soil health.