Mitarbeitende

The controlled uptake long‐term ammonium nutrition (CULTAN) fertilization technique consists of injecting a concentrated ammonium solution into the soil and aims to positively impact crop physiology and N use efficiency. This study assesses whether CULTAN can contribute to lower N leaching while maintaining yields in temperate regions with an annual precipitation of around 1000 mm or higher. We analyzed a 12‐year lysimeter experiment with two consecutive 6‐crop rotations and a 3‐year field experiment with winter wheat and maize in Switzerland. CULTAN was compared to a conventional surface application of ammonium nitrate fertilizer (ConvF). CULTAN achieved at least similar yields compared to ConvF in both studies and had a 38% lower yield‐scaled N leaching in the lysimeters. In both studies, CULTAN displayed higher nitrogen recovery efficiency (NRE) compared to ConvF, with an increase ranging from 8% to 17% depending on crop type, although a statistical significance was only found for winter wheat in the field study. NRE and N leaching were only weakly correlated, indicating that other N pathways are affected in the CULTAN fertilization system. Finally, we suggest that the timing and placement of the CULTAN injection need to be better adapted to the plant physiology and pedoclimatic conditions for optimal nutrient use and crop yields. In areas of high nitrate concentration in the groundwater, CULTAN can be an effective fertilization strategy complementing loss reduction measures.