Creating a dataset on fertilizers and fertilization recommendations

Within the scope of WP3 T 3.2 to determine yield responses to lower fertilization rates crop-specific N fertilizer amounts applied or recommended by countries for important agricultural crops were needed. In this context, FAOSTAT, Eurostat and IFASTAT databases were examined to access N fertilization amounts. These databases usually provide nitrogen fertilizer amounts for all agricultural production, regardless of crop. In addition, for some countries, fertilizer quantities by crop needed were not included (e.g. wheat, maize). For this reason, the national coordinator of each partner country of EJP SOIL was contacted to request the recommended amounts of N fertilizers for important crops in their country and their long-term yield values. 15 European countries (Austria, Germany, Netherlands, Belgium, Norway, Sweden, Switzerland, Hungary, Finland, Spain, Portugal, Poland, Latvia, UK and Turkey) provided these data. To estimate yields response to reduced fertilization an approach was created and used by bringing together data from various sources. The yields estimation was performed for –20% reductions in N fertilization for selected important crops which are wheat, maize, barley, sugarbeet, potato and rapeseed for 38 European countries listed in below excel sheet including Switzerland, Türkiye and UK . This approach also draws on the previously reviewed LTEs meta-analysis by Hijbeek et al. (2007) (with support of SOMMIT Project) and van Grinsven et al. (2022). As a result, considering FAOSTAT (2023) yield data, Country N fertilization data, Hijbeek et al. (2017) and van Grinsven et al. (2022) changes in yield for a 20% reduction in N fertilization rates for important crops were calculated for the Countries. For the rapeseed evaluation, FAOSTAT (2001-2022) mean yield data and N recommendation values of country datasets were used and the final estimations were calculated using Tian et al. (2023) equation. If yield reduction cannot be estimated from the above data for other European countries, matching was performed according to the pediclimatic zonation described in Toth et al. (2017).