CONTEXT: Reducing N surplus from agriculture without compromising yield and quality requires economically
and ecologically viable solutions.
OBJECTIVE: Based on field data, we investigated a technical and market-based solution to balance the economic
and environmental performance of nitrogen (N) fertilizer application in winter wheat in Switzerland.
METHODS: The technical solution, i.e. variable rate (VR) technology, was compared to the standard uniform
fertilizer application (ST) in terms of revenues and N balance over seven site-years between 2018 and 2020. The
potential of a market-based solution to align revenues and N surplus was investigated based on the relationship
between two indicators: the economic optimum (EO) of the revenues and the balanced N supply (BNS). The EOwas estimated using a production function approach. The BNS was empirically defined as the point at which the
N surplus estimated from total N input (N fertilizer + soil N supply) reaches a limit value of 30 kg N ha− 1
.
RESULTS AND CONCLUSIONS: On average, the revenues of VR were about 4% higher than in ST. The N surplus
was, on average, 32% (21 kg N ha− 1
) lower in VR compared with ST due to a 13% reduction in N inputs with no
significant differences in yield. Despite the differences across years and fields, VR appeared to be reducing N
surplus without losses in revenues in 5 out of 7 site-years. The revenue curve reached an EO at total N input of
205, 249 and 246 kg N ha− 1
, in the years 2018, 2019, and 2020, respectively. The BNS was calculated at 220,
195, and 178 kg N ha− 1 N inputs for the years 2018, 2019, and 2020, respectively. The results show that a price
increase of up to 5.4 times the current fertilizer price through taxes would be necessary in order to reduce the N
surplus to an environmentally friendly level. Such an increase would hardly be politically feasible.
SIGNIFICANCE: The reported data showed that VR technology appears as a viable solution for producing lower N
surplus at comparable revenue levels, thereby making it an option for small- to medium-scale winter wheat
production in Switzerland. The environmental benefit could encourage the financial support of technologies for
precise N management, which are often too expensive for these systems. Future research should verify or extend
the numeric values found in this study.