Humic Acid as Combined with Different Levels of N-P-K Fertilizer and Farmyard Manure to Enhance a Fodder Maize-Cowpea Intercropping System

In the summer season of 2021, a research study was conducted at the Department of Agronomy, Agricultural College and Research Institute, Tamil Nadu Agricultural University, Killikulam. The primary objective was to assess how varying doses of humic acid, in addition with the recommended fertilizer dose, affected the growth and physiological characteristics of African Tall fodder maize and CO 9 fodder cowpea under intercropping system. The study was laid down by using randomized block design with 12 treatment combinations, each replicated three times to reduce the experimental error. The study's results highlighted that applying 125% of the recommended fertilizer dose, supplemented with enriched farmyard manure at a rate of 750 kg/ha, and applying 20 kg/ha of humic acid with addition of foliar spray treatments comprising 1.0% Urea and 0.5% CaCl2 (Treatment 8) were found to yield the highest plant height, number of leaves per plant, branches per plant, and increased dry matter production. Furthermore, this approach demonstrated superior physiological attributes, including agronomic growth rate, relative growth rate, and net assimilation rate at various crop growth stages. Notably, this treatment also exhibited the largest leaf area when compared to control treatments (Treatment 12).