What you are trying to capture
A plot is a piece of land where coffee is grown. For each one you need its location in latitude and longitude, recorded to at least six decimal places. The EU Deforestation Regulation asks for a single point for plots of 4 hectares or less and a polygon around the perimeter for larger plots. Six decimal places is roughly 10 centimetres on the ground, far finer than any phone can measure, so the real limit is GPS accuracy, not the number format.
How accurate is a phone?
According to the European Forest Institute, smartphones typically achieve 3 to 5 metres in good conditions, while dedicated handheld GPS units reach 1 to 5 metres. Under dense canopy or on steep terrain, phone accuracy can degrade to 10 to 15 metres. Coffee in Kenya often grows on slopes, under shade trees such as grevillea, so plan for it.
Ways to improve accuracy:
- Wait for a good fix. Open the map a minute before you start and watch the accuracy figure settle.
- Average readings. Taking many readings over several seconds and averaging them reduces random error.
- Step into the open. Take point readings in a gap in the canopy within the plot.
- Keep the phone in the open. Hold it up, not in a pocket or bag.
- Record the accuracy. Store it with the plot so a reviewer can judge the data.
Mapping a plot of 4 hectares or less
- Confirm the farmer and the plot you are standing on.
- Walk to a central, open spot within the plot.
- Take an averaged reading for about 10 seconds.
- Check the point lands inside the plot on the satellite image.
- Record the farmer’s declared area. If it is over 4 hectares, map a boundary instead.
Mapping a boundary for a larger plot
- Start at a clear corner and walk the edge with the farmer, who knows where the boundary is.
- Let the app add a corner every few metres as you walk. KahawaTrace adds one every 5 metres and ignores poor fixes.
- Add extra corners by hand where the boundary turns sharply.
- Finish back near the start. The shape is closed automatically.
- Check the area against what the farmer declared and look at the shape on satellite imagery.
Common mapping mistakes
| Mistake | What it causes | How to avoid it |
|---|---|---|
| Boundary crosses itself | An invalid polygon the EU system rejects | Walk in one direction, without doubling back |
| Point taken at the farmer’s house | Location outside the coffee plot | Take the point within the planted area |
| Two agents map the same plot | Duplicates and overlaps | Check existing plots on the map first |
| Neighbouring boundaries overlap | Unclear ownership of land | Walk shared boundaries carefully; flag for review |
| Large plot saved as a point | Non-compliance for plots over 4 ha | Ask for the area first; use a polygon above 4 ha |
| Polygon with a hole in it | Holes are not processed by the EU system | Split the plot into two separate polygons |
After the field: review and GIS
Good mapping needs a second pair of eyes. A supervisor should compare each plot with satellite imagery before approving it. Store everything in WGS84, the coordinate system used by GPS, so it can be opened in GIS tools such as QGIS and uploaded as GeoJSON for EU due diligence. Our EUDR geolocation explainer covers the file format.
Mapping with KahawaTrace
KahawaTrace does this in a phone’s browser: averaged point readings, walk-the-boundary mapping with a corner every 5 metres, a live accuracy indicator, automatic checks for self-crossing boundaries, overlaps, duplicates and area mismatches, and a supervisor review queue. See GPS farm mapping.