Revalidation of potassium requirement for maize (Zea mays) in Eastern dry zone of Karnataka

Potassium is an essential nutrient for growth and development of crops, which requires greater attention in order to ensure enhanced crop production and mitigation of biotic and abiotic stress as well as improvement in crop quality. However, the reports indicate potassium is being depleted in Indian soils due to imbalanced applications. The present study was conducted to validate the potassium requirement on collecting around one hundred and fifty-eight (158) soil samples from different agro ecological situations (AES) under Eastern Dry Zone of Karnataka analyzed for available potassium and categorized into five classes such as very low, low, medium, high and very high. The critical limit for available potassium and plant potassium content and ratings for available potassium were determined by conducting pot culture experiment in soils collected from different locations under each category. The results revealed that the critical limit for soil available K was 105 kg K ha^-1 and 1.72 per cent plant K for maize crop. Based on continuous calibration curve the soil available potassium for Eastern dry zone of Karnataka can be revalidated and categorized as very low, low, medium and high in K recording corresponding to the value of < 105 kg ha^-1, 106 to 215 kg ha^-1, 216 to 380 kg ha^-1 and > 380kg ha^-1 available potassium respectively.