# A Python Framework for Crop Yield Estimation Using Sentinel-2 Satellite Data
## 2 Materials and Methods  
### Operational Crop Fields Under Investigation  
The operational crop fields under investigation are situated on the outskirts of the town of Ptolemaida, approximately 100 km west of Thessaloniki, within the Western Macedonia regional unit of Greece, Figure 1.  
The present research focuses on nine operational wheat crop fields, Figure 2, five (5) of these fields (marked in red) were sown with durum wheat (Triticum durum) and are located to the north and south of the town of Ptolemaida, while the remaining four (4) fields (marked in yellow) were sown with soft wheat (Triticum aestivum) and are situated to the west and south of Ptolemaida.  
Since this research was conducted in operational fields rather than controlled experimental conditions, key information such as crop installation dates and farmer interventions was obtained through farmer interview and ancillary data sources. However, the interviewed farmer did not maintain a detailed farm calendar. Additional data, including publicly available soil maps and meteorological records, were used to complement the information. The available information is summarized as follows:  
* Crop installation: The installation of crops across different fields took place over a period of 3 to 9 days.
* Wheat cultivars: \(\oslash\) & Durum wheat: Svevo\(\odot\)  Soft wheat: Giorgione
* Farmer interventions: Agronomic practices related to fertilization, weed control, and disease management were consistent across all fields under investigation. Specifically, this includes the following:
* Fertilization: \(\odot\)  Base fertilization: A winter application of fertilizer (N = 20, P = 23, K = 0) at a rate of 25 kg per stremma (1000 m\({}^{2}\)) in December. \(\odot\)  Spring fertilization: Two separate applications (N = 40, P = 0, K = 0) in early March and early April, with 15 kg per stremma (1000 m\({}^{2}\)) per application.
* Weed control: Application of Avoxa Maxx 12/2.88 OD (Syngenta) herbicide between 15 April and 20 April.
* Fungal disease prevention: Application of Amistar Gold 12.5/12.5 SC (Syngenta) fungicide in early May.  
Weather data, including temperature and precipitation during the growing season, were obtained from a nearby meteorological station located approximately 5 km from the study fields. The station, Ardassa (Coordinates: Latitude: 40.50 N, Longtitude: 21.60 E, Elevation: 625 m, CRS: WGS84; EPSG: 4326), is operated by the National Observatory  
Figure 1: Location of study fields (CRS: WGS84, EPSG: 4326).  
of Athens/Institute of Environmental Research and Sustainable Development and the data are public available ([[https://www.meteo.gr/](https://www.meteo.gr/)]([https://www.meteo.gr/](https://www.meteo.gr/)), accessed on 24 February 2025). Table 1 presents the monthly average temperatures (mean, maximum, and minimum) and total precipitation recorded during the study period.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Month**} & **Mean Maximum** & **Mean Minimum** & **Mean Temperature (\({}^{\circ}\)C)** & **Mean Temperature (\({}^{\circ}\)C)** & **Total Precipitation (mm)** \\ \hline December 2023 & 11.7 & \(-0.9\) & 3.6 & 72.8 \\ January 2024 & 8.8 & \(-0.8\) & 3.6 & 36.0 \\ February 2024 & 13.8 & 2.4 & 7.6 & 25.4 \\ March 2024 & 15.8 & 3.5 & 9.3 & 45.2 \\ April 2024 & 21.7 & 6.7 & 14.3 & 38.6 \\ May 2024 & 22.4 & 10.9 & 16.4 & 27.4 \\ June 2024 & 32.4 & 16.1 & 24.4 & 12.4 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Monthly weather conditions during the growing season.  
Figure 2: Location of the operational wheat crop field under investigation (CRS: WGS84, EPSG: 4326).  
Since specific soil data were not available from the farmer for each field, soil characteristics were derived from a publicly available soil map ([[https://iris.gov.gr/SoilServices/](https://iris.gov.gr/SoilServices/)]([https://iris.gov.gr/SoilServices/](https://iris.gov.gr/SoilServices/)), accessed on 24 February 2025). Table 2 summarizes the soil properties for the investigated fields.