SOIL FERTILITY MAPPING USING GIS IN RAMTHAL DRIP IRRIGATION AREA OF BAGALKOT
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Date
2018-07
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University of Horticultural Sciences, Bagalkot
Abstract
Bagalkot district has arid climate with low rainfall and high temperature. Soils
of this region are thirsty and to meet the water demand of farming community,
Karnataka Krishna Bhagya Jal Nigam Ltd, has launched Ramthal micro irrigation
project. This project addresses the thirsty issue but soil fertility which shows spatial
heterogeneity needs to be addressed. Hence a study was conducted to
characterization, map and identity fertility constraints in Ramthal irrigation area using
GIS and also to assess the performance of ABDTPA universal extractant in
determining the available micronutrient status of black soils of Bagalkot.
Soils of Ramthal area was strongly alkaline and non-saline in nature with low
in nitrogen, medium in available phosphorus, high in available potassium and low to
medium in available sulphur content. Exchangeable calcium, magnesium and sodium
were dominated cation in the soils. Status of micronutrients availability was in low
category for most of micronutrients except copper and manganese. Soil pH, organic
carbon, exchangeable calcium, sodium and Available manganese showed significant
spatial clustering. Soil sampling points (236 samples) were grouped into two clusters
using K-mean clustering and these two clusters showed distinct relation with
elevation. Out of total 634 ha area, major area (143.18 ha) was under high organic
carbon, medium sulphur and manganese followed by 122.86 ha under low organic
carbon, medium in sulphur and manganese.
A profile study of Ramthal area carried at different elevation (Top, Middle and
Bottom). Showed decreasing trend for pH, EC and sodium with elevation where as
nitrogen, calcium and sulphur showed opposite trend with elevation. Soil pH and EC
showed increasing trend with depth. Organic carbon, available nitrogen, phosphorus,
potassium and sulphur content showed decreasing with profile depth. Available
micronutrients Fe and Zn were low and showed decreasing trend with depth.
Available copper and manganese was sufficient in surface layer and deficient in sub
surface layer. Micronutrients trend with depth not observed and varied across the soil
profile.
The comparative study of traditional extractant and universal extractant
(ABDTPA) for micronutrients, (Fe, Cu, Mn, Zn) phosphorus and potassium showed
low correlation in the study area. The level of extraction of phosphorus by ABDTPA
was not in the detectable level of the instrument (MP-AES). Available iron, copper
and potash estimated by the ABDTPA was more compared to traditional extractant
DTPA.