Effect of Long-term Application of Manures and Fertilizers on Yield and Soil Nutrient Concentration in Rice Based Cropping System

All India co-ordinated research project on long term fertilizer experiment was set up at Regional Agricultural Research Station, Pattambi, Kerala during 1997. Research finding on yield and yield attributes as well as soil nutrient concentration as affected by the continuous application of manures and fertilizers on rice-rice cropping system was given in the paper. T₁₀ (100% NPK + in-situ green manuring) recorded the maximum number of tillers per hill (12.37). The number of panicles per hill was highest in T₁₀ and T₃ (150% NPK) with 11.37 and 11.07, respectively. Treatment, T₈ (100% NPK+FYM) recorded the highest number of seeds per hill (1149.3) and yield (4650 kg/ha). The available nutrient concentration in the soil varies depending on the individual nutrients. Organic carbon (1.96%) and available nitrogen (246.54 kg/ha) was found to be higher in T₈. Available phosphorus was highest in T₃ (19.39 kg/ha) followed by T₈ (19.34 kg/ha) and T₄, 100% NPK+lime (18.92 kg/ha). Highest available potassium was recorded in T₃ (84.83 kg/ha) where super optimal dose (150%) of NPK was applied.