Agronomic responses and economic returns from wheat–canola rotation under Humalite and urea applications

Humalite is a humic acid-rich biostimulant known for its ability to improve plant agronomic parameters and increase crop nitrogen use. Limited field research exists on Humalite effect, its application rate, and its interaction with urea, especially at reduced rates on grain agronomic parameters. Therefore, a field study was conducted from 2021 to 2023 at three Alberta sites—Battle River Research Group (BRRG), Gateway Research Organization (GRO), and St. Albert Research Station (St. Albert), in a split-plot design with four replications, three urea levels (i.e., recommended, half-recommend, and zero urea) combined with five Humalite rates (0, 56 (or 112), 224, 448, and 896 kg ha⁻¹). In 2021, the highest wheat yields were observed at half urea rates plus 224 kg ha⁻¹ at BRRG (35% yield increase), GRO (8.4% yield increase), and St. Albert (33.5% yield increase). In 2022, canola yields were unaffected by Humalite application rates. In 2023, wheat yields from half-recommended and recommended urea rates plots outperformed zero urea plots across all sites, regardless of Humalite rates. The highest wheat grain protein content values were observed at 224–448 kg ha⁻¹ of Humalite plus half-recommended or recommended urea rate. Depending on the site, the highest net revenue resulted from half urea rates plus Humalite at application rates between 112 and 448 kg ha⁻¹ in wheat, that is, optimal Humalite rate for increased profitability. Therefore, the incorporation of biostimulants such as Humalite can reduce urea use and contribute to the sustainability of wheat cropping systems.