With this indicator, the number and timing of nitrogen applications (organic or mineral) during the period of growth is evaluated. It is based on the recommendations of agronomists to split nitrogen inputs so that fertilisation sticks closer to crop needs. In consequence, less nitrogen may remain in the soil outside the periods of absorption by crops, which may reduce the risk of nitrogen loss (Recous et al., 1997). Generally, nitrogen application splitting allows a better match between applications and needs, a better consumption by crops and opportunities for adjustment of crop fertilisation. The objective is therefore to quantify the number of nitrogen inputs made "at the right time", i. e. during the period of crop needs, on the same plot. The interpretation has to be done in relation to the fertiliser amount and the yield (Klages et al., 2018).
Regularly, there are no European statistical data available on the timing and splitting of fertilisers. Some countries collect theses data at the regional or the national scale. At the catchment scale, information on fertiliser practice could be obtained by on-farm surveys. Another possibility could be an evaluation of farm management programs, which allow access to the farm management data of registered farmers. These data are confidential and not easy to obtain.
Therefore, timing of fertiliser application could be an indicator for improved farming practices, but data availability and the confidentiality of individual farm data has to be considered. Timing of fertiliser application and splitting of doses cannot stand alone as indicator but in connection to the application rate.