Response of Maize Yield Components and Weed Biomass to Nitrogen Fertilizer Levels and Herbicides Under Different Tillage Systems

Abstract

Maize productivity and weed suppression are influenced by the combined use of tillage, nitrogen, and herbicide practices, but integrated evidence on crop and weed community responses to these management factors across growing seasons and tillage contexts remains limited. This study aimed to assess variation in total weed biomass, dicot and monocot weed abundance, dominant weed species, maize aboveground biomass, harvest index, and grain yield under conventional tillage (CT) and minimum tillage (MT), two nitrogen rates (74 and 147 kg N ha−1), and five herbicide programs differing in active ingredient composition and application strategy, and to determine whether the relative importance of nitrogen and herbicide management varied with growing season and tillage context. Rainfed field trials were conducted in northwestern Hungary during the 2023 and 2025 growing seasons, and treatment-associated patterns were evaluated using exploratory analyses conducted separately for each year × tillage combination. In 2023, higher mean grain yield was observed at 147 than at 74 kg N ha−1 under both CT (from 12.25 to 14.96 t ha−1) and MT (from 11.95 to 15.41 t ha−1). In 2025, exploratory ANOVA indicated herbicide-program-associated variation in grain yield under both tillage systems, and the highest yields were observed under the dicamba + nicosulfuron + prosulfuron treatment, reaching (21.02 t ha−1) under CT and (14.82 t ha−1) under MT. Total weed biomass also showed herbicide-program-associated variation in the exploratory analyses in 2025, with the lowest biomass observed under tembotrione in CT (17.56 g m−2) and dicamba + nicosulfuron + prosulfuron in MT (22.68 g m−2). Patterns of dicot and monocot abundance associated with herbicide program also differed among year × tillage contexts, and the dominant weed species differed between years and tillage systems. Crop biomass and harvest index varied less consistently and depended on year and tillage system. Nitrogen × herbicide interaction terms had exploratory p-values ≥ 0.05 for all response variables. Because treatments were not independently replicated, these non-significant interaction terms should not be interpreted as evidence that biological interactions were absent. Taken together, the observed treatment-associated patterns were linked more closely to nitrogen management in 2023 and herbicide program in 2025, while weed-group responses also varied with year and tillage system. By examining together crop performance and weed community responses, the study suggests that observed responses to nitrogen and herbicide management depended on context rather than being consistent across seasons and tillage systems.