Assessment of spatially explicit actual, required and critical nitrogen inputs in EU-27 agriculture

Abstract

In this study we investigated critical nitrogen (N) inputs and N losses and their exceedances (actual inputs or losses minus critical inputs or losses) for agricultural soils in the EU-27 region in view of adverse effects.Critical N inputs were calculated based on a critical (i) ammonia emission rate related to critical N loads in view of biodiversity protection, (ii) N concentration in runoff to surface water of 2.5 mg N l -1 , related to the protection of aquatic ecosystems and (iii) nitrate (NO3 -) concentration in leachate to groundwater of 50 mg NO3l -1 , based on the safe limit for drinking water. In addition, we calculated the required N inputs to achieve target crop yields, which were set at 80% of the water-limited yield potential. Calculations were performed with the INTEGRATOR model for ca 40,000 unique soil-slope-climate combinations and then aggregated at NUTS3-, country-or EU-27 level. Results show that critical N inputs at EU-27 level as compared to actual (year 2010) N inputs are 31% lower to protect biodiversity and 43% lower to protect surface water quality. Critical N inputs are most strongly exceeded in regions with high livestock densities, such as Ireland, the Netherlands, Flanders in Belgium, Brittany in France and the Po valley in Italy.Inversely, required N inputs to attain target crop yields at EU-27 level are ca. 40% higher. Especially in Eastern Europe, there is a large potential to increase yields by increasing N fertilization, but this generally requires strongly improved N use efficiency (NUE), since critical N inputs are mostly lower. Using a maximum plausible NUE, the surface water criterion cannot be achieved on 17% and 25% of all agricultural land at actual crop yield and target crop yields, respectively. Similarly, a maximum plausible reduction in NH3 emission fractions also still causes exceedances of critical N loads in view of biodiversity protection.Reducing agricultural production is needed to protect biodiversity and/or water quality in those regions.

Halving mineral nitrogen use in European agriculture: Insights from multi‐scale land‐use models

“…The welfare gains for European citizens could thus be considerable as reported in Sutton et al (2011). Furthermore, de Vries and Schulte‐Uebbing (2020) argue that for 15%–20% of EU agricultural land a reduction in fertilization rates and yields is inevitable in order to attain water and air quality objectives.…”

A safe agricultural space for biodiversity

“…To refine those assessments, and better integrate all forms of biodiversity in food systems scenarios, we need a framework that accounts for the combined multivariate effects of agriculture, instead of individual stressors (Benton et al, 2003). Treating drivers of biodiversity loss like N (e.g., de Vries et al, 2021) and P pollution (e.g., Bennett, 2011), GHG emissions (e.g., Popp et al, 2017), or water withdrawal (e.g., Jägermeyr et al, 2017) individually, rather than as interacting components behind biodiversity loss, may lead to partial solutions for biodiversity conservation.…”

Comparison of nitrogen fertilisation recommendations of West European Countries

“…The European statistics on water quality point out that those values have evolved without measured improvement for the last 30 years (European Environment Agency, 2022). According to a N transfer model run by de Vries and Schulte‐Uebbing (2019), the risk of eutrophication of waterbodies is the most critical threat and necessitates a reduction in the N‐leakages from fields by a factor of two, based on a critical N concentration of 11 mg NO 3 − L −1 (2.5 mg N L −1 ).…”