Influence of real time nitrogen management and optimisation of phosphorus and potassium on productivity of grain sorghum in South Odisha

Sorghum is emerging as a climate-resilient cereal due to its adaptability to heat and soil moisture stress; however, its high nutrient demand necessitates efficient nutrient management for sustaining productivity under changing climatic conditions. Conventional blanket fertiliser application often leads to nutrient imbalance, low use efficiency and environmental concerns. In this context, the present study was conducted to evaluate the effect of precision nitrogen management integrated with different levels of phosphorus and potassium on growth, yield attributes and yield of grain sorghum. The experiment was laid out in a factorial randomised block design with four nitrogen management practices, namely recommended dose of nitrogen, Soil Plant Analysis Development (SPAD)-based sufficiency index < 90 %, SPAD-based sufficiency index < 95 % and Normalised Difference Vegetation Index (NDVI)-based relative index > 1.15 and 3 levels of phosphorus and potassium (75 %, 100 % and 125 % of recommended dose), replicated thrice. The results revealed that precision nitrogen management significantly influenced growth attributes, yield attributes and yield of sorghum. Among the nitrogen management practices, SPAD-based sufficiency index < 95 % recorded the maximum plant height, dry matter accumulation, leaf area index, yield attributes, grain yield (3274 kg/ha), stover yield (11230 kg/ha) and biological yield (14503 kg/ha) and remained superior to the conventional recommended dose of nitrogen. Similarly, the application of 125 % recommended dose of phosphorus and potassium resulted in significantly higher growth and yield parameters compared to lower levels. The interaction effect showed that SPAD-based sufficiency index < 95 % in combination with higher levels of phosphorus and potassium produced the highest yields. Regression analysis further confirmed a strong positive relationship between growth and yield attributes with grain yield. The study concluded that precision nitrogen management and SPAD-based sufficiency index, along with adequate phosphorus and potassium fertilisation, can be effectively adopted to enhance the productivity of grain sorghum.