Effect of Humic Acid on Yield, Soil Nutrient Availibilty and Chemical Status after Harvest of Wheat

Abstract

Wheat (Triticum aestivum L.) is a major staple crop, but its productivity and soil sustainability are increasingly challenged by the excessive and imbalanced use of chemical fertilizers. Integrated Nutrient Management, including the use of humic acid, offers a promising approach to improve soil health, nutrient availability, and crop productivity under intensive cultivation systems. A field experiment was conducted during the rabi seasons of 2023–24 and 2024–25 at the Pulse Research Station, Anand Agricultural University, Vadodara, Gujarat, to assess the effect of humic acid on soil chemical properties and nutrient dynamics under wheat (Triticum aestivum L.) cultivation. The study was laid out in a randomized block design comprising ten treatments with varying levels of recommended dose of fertilizers (RDF) in combination with soil and foliar application of humic acid. The results indicated that post-harvest soil pH and electrical conductivity were not significantly affected by different treatments. Application of 100% RDF + humic acid @ 10 kg ha-1 (T4) recording the significantly highest values of grain yield (5242 kg ha-1), straw yield (6137 kg ha-1), available nitrogen (308 kg ha-1) and phosphorus (61.95 kg ha-1) during 2023–24, 2024–25 and pooled analysis, respectively, remaining statistically comparable with T3. In contrast, available potassium did not show significant variation across treatments. Application of humic acid significantly increased soil organic carbon content and DTPA-extractable micronutrients (Fe, Zn, Mn and Cu), with the highest concentrations observed under T10 (75% RDF + soil application of humic acid @ 15 kg ha-1 + foliar spray @ 0.2% humic acid), followed by T7, may be attributed to the foliar application of humic acid, which enhances direct nutrient absorption and utilization by plants, thereby minimizing nutrient fixation and residual buildup in the soil. Overall, the results demonstrate that the combined application of humic acid and inorganic fertilizers significantly enhances wheat productivity, enriches soil organic carbon and improves nutrient availability, thereby promoting sustainable soil fertility management.