Surface and sub-surface soil potassium dynamics in a selected red soil type

Abstract

The potassium dynamics in red soils of maize growing areas of Haveri district, Karnataka was studied in UAS, Dharwad during 2016-17. Potassium exists in soil in different forms such as water soluble, exchangeable, non-exchangeable, lattice K. The available potassium varied from 268.80 to 483.84 kg ha-1 in surface layer and sub-surface layer ranged from 215.04 to 376.32 kg ha-1. The water soluble potassium varied from 1.66 to 4.69 mg kg-1 with a mean of 2.91 mg kg-1 in surface depth. The sub-surface water soluble K content varied from 1.31 to 3.39 mg kg-1 with a mean of 2.24 mg kg-1. The water soluble potassium in selected red soils of maize growing areas of Haveri district varied from 1.66 to 4.69 mg kg-1 with a mean of 2.91 mg kg-1 in surface depth. The sub-surface water soluble K content varied from 1.31 to 3.39 mg kg-1 with a mean of 2.24 mg kg-1. The exchangeable potassium content of red soils ranged from 44.80 to 78.40 mg kg-1 in surface layer. The sub-surface exchangeable potassium content of red soils varied from 30.60 to 67.20 mg kg-1. The water soluble and exchangeable K was more in surface than in sub-surface. The non-exchangeable potassium ranged from 495.88 to 653.66 mg kg-1 in surface and 592.27 to 860.85 mg kg-1 in sub-surface layer. The lattice potassium of red soils ranged from 0.92 to 1.28 per cent in surface samples. The lattice potassium in sub-surface layer ranged from 0.98 to 1.42 per cent. The total potassium in surface depth of red soils varied from 0.97 to 1.35 per cent and that of sub-surface ranged from 1.05 to 1.50 per cent. The mean non-exchangeable, lattice and total K was noticed in sub-surface layer than in surface layer. The variation in potassium content of surface and sub-surface layers was mainly due to variation in clay content, weathering intensity and cultural practices.