Effect of Long-term Continuous STCR based Fertilization on Potassium Pools and Balance in Calcareous Soil under Rice based Cropping System

Potassium (K) is essential for soil, plant and human nutrition. In calcareous soils, high Ca levels suppress the K uptake by the crops therefore, crops growing in these soils often require above normal levels of K fertilization for satisfactory plant growth. Therefore, a long-term experiment was started in calcareous soil (medium in available K) replicated thrice in randomized block design with rice-based cropping system and nine treatments [T1- control, T2-FP, T3-GRD, T4-YT 35q/ha, T5-YT 40 q/ha, T6-YT 45 q/ha, T7-STCR (YT 35 q/ha) + IPNS, T8-STCR (YT 40q/ha) + IPNS, T9-STCR (YT 45 q/ha) +IPNS at Experimental Farm, RPCAU, Pusa, Samastipur, Bihar, India during kharif-2019. Continuous addition of STCR based fertilizer along with 5 tons ha-1 compost improved soil organic carbon, CEC, available potassium status and potassium balance whereas control unfertilized decreased the most, results unsustainable yields and soil fertility. Treatment T9 for rice based cropping system was superior over all the other treatments in potassium fractions, chemical properties and potassium balance of surface (0-15 cm) and sub-surface soil (15-30 cm).