Effect of soil and foliar application of humic acid on wheat yield and nutrient uptake

Declining soil health and excessive dependence on chemical fertilizers under intensive agricultural practices have increased the need for sustainable nutrient management strategies. Humic acid has gained considerable attention for its potential to improve nutrient availability, crop growth and productivity under reduced fertilizer application. Therefore, a field experiment was conducted during the rabi seasons of 2022–23 and 2023–24 to evaluate the effect of different methods of humic acid application in combination with reduced nitrogen (N), phosphorus (P) and potassium (K) levels on growth, yield, nutrient uptake and economic returns of wheat. The experiment was laid out in a randomized complete block design (RCBD) with twelve treatment combinations and three replications. Application of 80% of recommended NPK (100:50:25 kg ha−1) along with two foliar sprays of humic acid powder at 4 g L−1 (T12) recorded higher growth parameters, yield attributes, grain and straw yield, nutrient uptake and economic returns, which remained statistically comparable with T11. However, the highest benefit-cost ratio was recorded with application of 80% of recommended NPK along with two foliar sprays of humic acid powder at 2 g L−1 (T11). Correlation analysis revealed significant positive relationships between dry matter accumulation and grain yield, and between effective tillers and grain yield at the 5% significance level, with correlation coefficients (r) of 0.92 and 0.83, respectively. Overall, application of humic acid in combination with reduced NPK levels improved wheat productivity, nutrient uptake and economic returns, indicating its potential for sustainable wheat production.