Fertility Status of Groundnut Growing Calcareous Vertisols of Dharwad District, Karnataka
V. Manasa *
Department of Soil Science, Indian Institute of Rice Research, Rajendranagar, Hyderabad, Telangana - 500030, India and Department of Soil Science and Agricultural Chemistry, University of Agricultural Sciences, Dharwad, Karnataka - 580005, India.
N. S. Hebsur
Department of Soil Science and Agricultural Chemistry, University of Agricultural Sciences, Dharwad, Karnataka - 580005, India.
P. L. Patil
Department of Soil Science and Agricultural Chemistry, University of Agricultural Sciences, Dharwad, Karnataka - 580005, India.
M. Hebbara
Department of Soil Science and Agricultural Chemistry, University of Agricultural Sciences, Dharwad, Karnataka - 580005, India.
B. N. Aravind Kumar
Department of Soil Science and Agricultural Chemistry, University of Agricultural Sciences, Dharwad, Karnataka - 580005, India.
R. Gobinath
Department of Soil Science, Indian Institute of Rice Research, Rajendranagar, Hyderabad, Telangana - 500030, India.
*Author to whom correspondence should be addressed.
Abstract
A soil survey was carried out in different groundnut growing calcareous Vertisols of Dharwad district, Karnataka, India. One hundred surface composite soil samples were collected from five talukas (mandal) of Dharwad district and analyzed for soil chemical properties and nutrient status. The results showed that soil pH, electrical conductivity, organic carbon, free CaCO3 content ranged from 6.9-8.9, 0.15-1.79 dS m-1, 2.40-9.10 g kg-1, 5.8 -22.2 respectively across the regions. Available nitrogen, phosphorus (P2O5), potassium (K2O) and sulphur contents widely varied from 107-268, 18.5 - 56.0 and 386- 876, 14.8- 41.0 kg ha-1, respectively. On the basis of nutrient index values, groundnut growing calcareous soils of Dharwad were categorized as deficient in available nitrogen, medium in available phosphorus and high in available potassium. Most of the samples were deficient in available Fe and Zn whereas DTPA-extractable Cu and Mn were above the critical limits. A significant and positive correlation was found between organic carbon and available nitrogen (r=0.730**). However, a negative correlation was observed between Soil pH and micro nutrients while CaCO3 was negatively correlated with available iron (r=-0.31**).
Keywords: Fertility status, groundnut, macro and micro nutrients, nutrient index, organic carbon, correlation