Studies on Forms and Distribution of Soil Potassium in Selected Maize Growing Areas of Haveri District
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Date
2017-07
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University of Agricultural Sciences, Dharwad
Abstract
Potassium exists in different forms viz., water soluble, exchangeable, non-exchangeable and lattice potassium and these forms are in a state of quasi-equilibrium with each other. These different forms of potassium and their distribution in surface and sub-surface layers were studied in twenty representative red and black soil types spreading over seven taluks of Haveri district of Karnataka during 2016-17 at UAS, Dharwad.
The soils studied were generally sandy clay loam to clay in texture, slightly acidic to near neutral in reaction and different forms of potassium were high in black soils compared to red soils. The water soluble and exchangeable K was higher in surface sample than in the sub-surface of both the soil types except for non-exchangeable, lattice and total K which were high in sub-surface. The water soluble K showed a significant and positive correlation with sand in red (r= 0.755*) and black (r= 0.527*) soils. The exchangeable K was significantly and positively correlated with CEC. Whereas, non-exchangeable K, lattice K and total K showed positive correlation for clay. The higher AReK in red soils indicated the immediate availability of K. The labile K in black soils recorded higher compared to red soils. The specific site K varied depending on amount of clay and organic matter present. The planar site K was high in surface samples of red soil (0.11 cmol kg-1) compared to that of black soil. The black soil type registered higher PBCK [42.86 and 90.90 (cmol kg-1)/(mol l-1)0.5 in surface and sub-surface layers, respectively]. The -∆G0 was higher in sub-surface soils of both the soil types compared surface. The present study suggests that the coarse textured red soils having low PBCK need frequent K fertilization for sustained production of maize crop.