Sensor-based precision nutrient and irrigation management enhances the physiological performance, water productivity, and yield of soybean under system of crop intensification.

Sensor-based decision tools provide a quick assessment of nutritional and physiological health status of crop, thereby enhancing the crop productivity. Therefore, a 2-year field study was undertaken with precision nutrient and irrigation management under system of crop intensification (SCI) to understand the applicability of sensor-based decision tools in improving the physiological performance, water productivity, and seed yield of soybean crop. The experiment consisted of three irrigation regimes [I: standard flood irrigation at 50% depletion of available soil moisture (DASM) (FI), I: sprinkler irrigation at 80% ET (crop evapo-transpiration) (Spr 80% ET), and I: sprinkler irrigation at 60% ET (Spr 60% ET)] assigned in main plots, with five precision nutrient management (PNM) practices{PNM-[SCI protocol], PNM-[RDF, recommended dose of fertilizer: basal dose incorporated (50% N, full dose of P and K)], PNM-[RDF: basal dose point placement (BDP) (50% N, full dose of P and K)], PNM-[75% RDF: BDP (50% N, full dose of P and K)] and PNM-[50% RDF: BDP (50% N, full P and K)]} assigned in sub-plots using a split-plot design with three replications. The remaining 50% N was top-dressed through SPAD assistance for all the PNM practices. Results showed that the adoption of Spr 80% ET resulted in an increment of 25.6%, 17.6%, 35.4%, and 17.5% in net-photosynthetic rate (P), transpiration rate (T), stomatal conductance (G), and intercellular CO concentration (C), respectively, over FI. Among PNM plots, adoption of PNM resulted in a significant (=0.05) improvement in photosynthetic characters like P (15.69 µ mol CO m s), T (7.03 m mol HO m s-), G (0.175 µmol CO mol year), and C (271.7 mol HO m s). Enhancement in SPAD (27% and 30%) and normalized difference vegetation index (NDVI) (42% and 52%) values were observed with nitrogen (N) top dressing through SPAD-guided nutrient management, helped enhance crop growth indices, coupled with better dry matter partitioning and interception of sunlight. Canopy temperature depression (CTD) in soybean reduced by 3.09-4.66°C due to adoption of sprinkler irrigation. Likewise, Spr 60% ETc recorded highest irrigation water productivity (1.08 kg ha m). However, economic water productivity (27.5 INR ha m) and water-use efficiency (7.6 kg ha mm day) of soybean got enhanced under Spr 80% ETc over conventional cultivation. Multiple correlation and PCA showed a positive correlation between physiological, growth, and yield parameters of soybean. Concurrently, the adoption of Spr 80% ET with PNM recorded significantly higher grain yield (2.63 t ha) and biological yield (8.37 t ha) over other combinations. Thus, the performance of SCI protocols under sprinkler irrigation was found to be superior over conventional practices. Hence, integrating SCI with sensor-based precision nutrient and irrigation management could be a viable option for enhancing the crop productivity and enhance the resource-use efficiency in soybean under similar agro-ecological regions.