DOI: 10.5281/zenodo.17658923
title: Simulated BBCH crop growh stages as function of calendar dates across the EU including underlying observations

description: EU Regulation requires environmental risk assessments (ERA) for non-target organisms exposed to active substances in plant protection products. To advance the ERA of pesticides effectively, it is important to have accurate prediction of crop phenology spatially across the EU. Therefore, a study was conducted to enhance pesticide risk assessment for non-target organisms by precisely mapping crop development stages (BBCH ) across the EU by developing predictive models of crop sowing dates as well as calibrated models of crop phenology. 

We did an extensive data collection and curation from public sources like C2D2 (Hughes et al., 2023), PEP725 (Templ et al., 2018), and TEMPO (Maury et al., 2023), alongside literature, creating a harmonized database phenological observations. Comparisons revealed C2D2's broad spatial coverage across Europe, while PEP725 concentrated in Central Europe and TEMPO in France. C2D2 and TEMPO offered observations across various growth stages, unlike PEP725 which focused on sowing, emergence, and harvest.  A model for spatially predicting sowing dates was developed using a temperature-driven rule, supplemented by a median rule for regions where management practices (like irrigation) heavily influence planting, as seen with maize in Southern Europe. The WOFOST cropping system model's phenological sub-model was used to simulate phenology. It predicts crop development through a dimensionless development stage (DVS) variable which is 0 at crop emergence and reaches 1.0 at anthesis and 2.0 at maturity. The model accounts for temperature as well as photoperiod and vernalization for winter crops. The temperature sum requirements to anthesis (TSUM1) and maturity (TSUM2) were calibrated using observed sowing, flowering and maturity dates from the datasets mentioned above. Observations were pooled by defining agroecological zones with similar agroclimatic conditions and all observations in an agroecological zones where used jointly to estimate the TSUM1 and TSUM2 parameters. Next, the intermediate BBCH stages were connected to the DVS scale as defined by WOFOST. Finally, the calibrated model was used to predict development stages based on the predicted sowing dates over the entire European 10x10 km grid in order to have wall-to-wall predictions of all BBCH development stages. 

The simulated BBCH crop growth stages and their corresponding observations are provided. The publication contains two SQLite databases:



Simulated BBCH crop growth stages (simoutput_final_v20250630.db)

Observed phenology data (EFSA_CURATED_DATA_v20250616-without-PEP725.db)


For the observed phenology data, we include only those datasets that can be redistributed under the original data policies. Consequently, data from PEP725 is not included. For the other data sets the original data policy, defined in table DATASETS (EFSA_CURATED_DATA_v20250616-without-PEP725.d), must be followed. Thus the user must check the data license of each of these datasets before starting to use or redistribute the data.

The simulated BBCH crop growth stages are available under Creative Commons Attribution 4.0 International.

The structure of these databases is described in the document 'Readme simulated BBCH stages and observations.pdf'. To fully understand the background of the data, the reader is referred to the scientific report. Finally, an animation video, SBAR_BBCH_full.avi, is available presenting a time-lapse of simulated development stage for spring barley. 

This work was carried out under the Framework Partnership Agreement (GP/EFSA/PREV/2020/02) between the European Food Safety Authority (EFSA) and Wageningen Environmental Research (WENR), which aims to advance concepts and methodologies for assessing the exposure of terrestrial non-target organisms to plant protection products.