Kornertrag, Stickstoffparameter und Energieeffizienz von Körnermais bei unterschiedlichen mineralischen und organischen Düngestrategien mit 180 kg N/ha in einem Langzeitdüngungsversuch in der Steiermark

At a high-yield site in the Styrian district of Hartberg-Fürstenfeld (Kalsdorf ), a long-term nitrogen (N) fertilization trial was conducted over ten experimental years (2011–2016, 2018, 2020–2022) to investigate grain yield, N uptake, N balance, and energy efficiency. The fertilization treatments (unfertilized, nine treatments with 180 kg N/ha, including seven mineral and two biogas slurry treatments) each with four replications were arranged in a generalized lattice design with incomplete blocks. The total energy input, consisting of direct energy input (heating oil and electricity for drying, fuel for field operations) and indirect energy input (mineral N fertilizer, seeds, plant protection, machinery), amounted to 19.0 GJ/ha for the unfertilized control, 30.7 GJ/ha for the mineral fertilization variants, and 20.6 GJ/ha for the biogas slurry variants. Drying energy accounted for up to 47%, and mineral fertilizer energy accounted for up to 21% of the total energy input. The seven mineral fertilization variants showed no significant differences in grain yield, which ranged between 14,757 and 15,025 kg/ha. Biogas slurry fertilization produced lower grain yields (11,803 kg/ha – single application, 12,622 kg/ha – twice application) with high energy efficiency. A twice application is more energy efficient than a single application. The average N balance was −57.1 kg N/ha for the unfertilized control, +24.6 kg N/ha for the mineral treatments, and +58.4 kg N/ha for the biogas slurry treatments. With increasing grain yield, the N balance decreased.