Effect of humic acid on soil fertility and yield of foxtail millet-chickpea cropping system in Andhra Pradesh, India

A field experiment was conducted at the College Farm, Agricultural College, Mahanandi, Acharya N. G. Ranga Agricultural University (ANGRAU), during the kharif and rabi seasons of 2020-21 and 2021-22 to evaluate the impact of chemical fertilizers and humic acid on soil fertility and grain yield of the foxtail millet-chickpea cropping system. The experiment followed a split-plot design with three replications, comprising four main treatments of chemical fertilizers and six subplot treatments of humic acid applications. The results indicated that soil available nutrient content (N, P), dry matter production and grain yield of foxtail millet were significantly higher with the application of 100% recommended dose of fertilizers (RDF), though it was statistically at par with 75% RDF. Among the humic acid treatments, the highest soil nutrient content, dry matter production, grain and straw yield were observed with 20 kg ha^-1 humic acid as soil application combined with 0.2% foliar application of humic acid over two consecutive years. A similar trend was observed in the succeeding chickpea crop regarding soil nutrient status, grain yield, and dry matter production. These findings suggest that integrating humic acid with chemical fertilizers enhances soil fertility and productivity in the foxtail millet-chickpea cropping system. Given the limited research on humic acid application in cereal-pulse cropping systems, this study provides valuable insights into its role in sustainable crop production.