Dynamics of Soil Potassium Under Different Cropping Systems in Y.S.R Kadapa District of Andhra Pradesh, India

Dynamics of soil potassium under five important cropping systems of Y.S.R. Kadapa district of Andhra Pradesh was studied. From each cropping system five surface and subsurface soil samples were collected from fallow – bengalgram, sunflower – sesame, paddy – paddy, groundnut monocropping and groundnut – groundnut cropping systems in 2018-2019. The available K content varied from 73.65 mg kg-1 to 282.80 mg kg-1 and from 51.30 mg kg-1 to 160.90 mg kg-1, water soluble K content varied from 5.5 mg kg-1 to 43.30 mg kg-1 and from 5.05 mg kg-1 to 17.25 mg kg-1, exchangeable K content varied from 68.10 mg kg-1 to 254.10 mg kg-1 and from 43.70 mg kg-1 to 144.05 mg kg-1, non-exchangeable K content varied from 309.95 mg kg-1 to 970.35 mg kg-1 and from 238.80 mg kg-1 to 623.00 mg kg-1, lattice K content varied from 11498.10 mg kg-1 to 23326.60 mg kg-1 and from 6460.20 mg kg-1 to 35828.20 mg kg-1 and total K content varied from 11920 mg kg-1 to 24190 mg kg-1 and from 6990 mg kg-1 to 33330 mg kg-1 in surface and sub-surface soils, respectively under different cropping systems. Available K ranged from 0.58 to 1.33 per cent and 0.11 to 1.58 per cent, water soluble K 0.07 to 0.18 per cent to 0.03 to 0.18 per cent and 0.03 to 0.18 per cent, exchangeable K 0.44 to 1.20 per cent and 0.14 to 1.44 per cent, non-exchangeable K 2.33 to 5.08 per cent and 1.15 to 6.26 per cent and lattice K 94.00 to 97.08 per cent and 92.16 to 98.68 per cent in surface and sub-surface soils of total potassium, respectively under different cropping systems. All the forms of K were correlated with each other revealing the existence of dynamic equilibrium among them