Effect of Precision Nutrient Management and Humic Substances on Growth and Yield Attributes of Wheat (Triticum aestivum L.) in the Hyper-Arid Region of Rajasthan, India

Background: Wheat cultivated on loamy sand soils in hyper-arid Rajasthan requires nutrient management suited to limited soil nutrient retention. This study assessed the effects of precision nutrient management and soil-applied humic substances on wheat growth and yield attributes. Methods: A field experiment was conducted at Bikaner during the 2024–25 and 2025–26 rabi seasons using a split-plot design with three replications. Five nutrient treatments comprised an unfertilised control, the recommended dose of fertilisers (RDF), Nutrient Expert (NE), NE with leaf colour chart (LCC)-guided nitrogen application, and NE with chlorophyll meter (SPAD)-guided nitrogen application. Five humic-substance treatments comprised a control and combinations of humic acid (HA; 20 or 30 kg ha⁻¹) and fulvic acid (FA; 10 or 15 kg ha⁻¹). Results were pooled over two seasons. Results: NE + SPAD produced the tallest plants (86.55 cm), the most total tillers (541 m⁻²) and effective tillers (407 m⁻²), and the longest (9.11 cm) and heaviest (2.27 g) spikes. These results were statistically comparable with NE + LCC. NE alone was comparable with RDF while applying 8.3% less nitrogen and 17.5% less P₂O₅. HA 30 + FA 15 kg ha⁻¹ gave the highest numerical responses but was statistically comparable with HA 30 + FA 10 kg ha⁻¹. No significant interaction between the two treatment factors was detected. Conclusion: Sensor-guided NE and soil application of HA at 30 kg ha⁻¹ improved the measured growth and yield attributes under the experimental conditions.