Distribution of Potassium under Prominent Cropping Systems in Scarce Rainfall Zone of Andhra Pradesh, India

Six prominent cropping systems in scarce rainfall zone of Andhra Pradesh viz., groundnut-horsegram, cotton-fallow, fallow-bengalgram, groundnut monocropping, paddy-paddy and paddy-groundnut cropping systems were selected to study the soil available potassium status and forms of potassium. Twenty soil samples from each cropping system were collected at 0-15 cm (surface soil) and 15-30 cm (sub-surface soil) depth. The available potassium content in the study area was varied from medium to high. The highest available K (216 and 148 mg kg-1), water soluble K (19.94 and 14.25 mg kg-1) and exchangeable K (196 and 133 mg kg-1) were recorded under paddy-paddy cropping system in both surface and sub-surface soils, respectively. The highest non-exchangeable K (609 and 441 mg kg-1) was recorded under paddy-groundnut cropping system in both surface and sub-surface soils, respectively. However, lattice K (34072 and 25614 mg kg-1) and total K (34666 and 26066 mg kg-1) were recorded highest under groundnut monocropping system in both surface and sub-surface soils, respectively.