To explore the suitability of various sources of potassium (K) application on K fractions (watersoluble K, Exchangeable K, 1 N HNO3 soluble K, Non-exchangeable K) through incubation study. An incubation experiment was conducted at department of soil science and agricultural chemistry, Bihar Agricultural University, Sabour, Bhagalpur in completely randomized block design with 8 treatments viz., T1 (no K application), T2 (50 per cent RDK), T3 (100 per cent RDK), T4 (150 per cent RDK), T5 (50 per cent RDK + 50 per cent K by Azolla), T6 (50 per cent RDK + 50 per cent K by vermicompost), T7 (100 per cent K by Azolla) and T8 (100 per cent K by vermicompost) replicated thrice and kept in incubator at 25 deg. Celsius and used to assess various forms of K in soil at 0, 35, 70 and 105 days of incubation. Full dose of N and P were applied in all the treatments through urea and SSP respectively. However, potassium was supplied through muriate of potash (MOP ; 60 per cent K2O), vermicompost ( per cent K) and Azolla ( per cent K on dry wt. basis). | An incubation experiment to study potassium fractions using azolla vermicompost and muriate of potash as potassium sources in inceptisol of Bihar
