A study was conducted to evaluate a site specific drip fertigation system
based on the nutrient status maps prepared with help of GIS at Instructional Farm
KCAET, Tavanur. Seventy soil samples were collected at a grid interval of
50×50m and different soil parameters such as pH, Electrical conductivity, Organic
Carbon, Available Nitrogen, Available Phosphorous and Available Potassium in
the soil were determined. The nutrient index rating of the study area indicate that,
nitrogen and potassium shows “low fertility”, whereas phosphorous found to be
under “high fertility” range in the study area.

Using the spatial variability maps of the nutrients, two test plots, one from
high fertility zone and one from low fertility zone were identified with the help of
GPS for raising the test crop tomato. The experimental plot was laid out in a
Completely Randomized Design (CRD) with four treatments and four
replications. The results showed increase in yield and growth parameters under
site specific drip fertigation treatment in low fertility area due to the adequate
fertiliser application than general recommendation, which might be inadequate for
that low fertility area. In case of high fertility area, reduction of fertilizer to site
specific requirement has produced almost similar result of general
recommendation which indicates that site specific dose was sufficient to produce
optimum yield from the crop. Moreover, a site specific drip fertigation helped to
achieve a higher water and nutrient use efficiency with high economic return of
agricultural produce.

From this study, it can be concluded that nutrient status map prepared
using GIS for a particular area can be used as an effective tool for the better
nutrient management in that area for maximum productivity. Instead of going
blanket nutrient recommendation, a site specific nutrient recommendation may
help the farmers who want to achieve higher profit from unit land area by using
optimum inputs, thereby reducing environmental stress due to over fertilizer
application.