OFE in practice: a complex story

Drones supporting the farmer in field inspections: validation by on-farm testing

At the beginning of June we started with an On Farm Experiment (OFE) on a field of drip irrigated onions. The goal of the OFE was to design and investigate a protocol for leakage inspection of the drip irrigation, which was a specific question of the farmer. Leakage inspections are very time consuming. An automation of the process can optimize the farmers’ work.

Leakages in drip irrigation are not only a waste of water, but they can negatively affect crop establishment during the weeks after sowing. The leakage detection was done by means of a drone with thermographic and RGB cameras. The field is approximately 5 hectares which makes one flight that lasts about 20-30 min flight time with 10-15 min data processing time. The onions where sown end of March, followed by a very dry period. In April and May 2025, respectively 20 mm/m² and 27 mm/m² of precipitation was recorded in Uccle (the central weather station of Belgium), which is less than half of the average for those months. Despite the intention was to start irrigating the beginning of June but because the crop received enough rain early in June, the first irrigation was postponed till the 17th of June.

5 ha
Size of the field
20-30 min.
Flight time
15 min.
Data processing time


Next to onions, the farmer also grows arable crops, potato, field vegetables and has a little cattle. The farm is located in the agricultural region Southwest Flanders and the OFE field is a sandy loam soil. The OFE process started back in April by discussing the scope and set-up with the farmer. In this OFE, the drone service provider is the entity bringing in all the experience and knowledge about the drone, camera and data processing. It is the drone service provider who develops the requested procedure and brings the best practices to the farm.

OFE preparation work amid the intense rush of farmers’ spring field work is done … over the phone

The preparatory work for this OFE was done between April and beginning of June. Because of the dry and warm spring this year, field works in arable farming started early this year. As a result, the farmer didn’t have time at all to sit and discuss the set-up, the work plan and the expectations. Thus, we couldn’t follow our own advice from the OFE guide.

It should be noted that everything was arranged over the phone, and this is one essential takeaway, if you want to get things done by farmers, you need to phone them. They are busy and quite often don’t catch up with emails but they do answer phone calls. 

Furthermore it is also important not to expect too much farmer commitment into the administrative part of the research. In this case, the OFE was made possible with EU funding. Normally the funding proposal needed to be prepared and submitted by the farmer and the drone service provider but, we as a researchers have completely taken over the role of the farmer in this because otherwise we wouldn’t have been able to come to the point where we received the funding and we could actually start the OFE.




You can’t control the weather

In this particular OFE, a lot depended on the weather. Early in June there was enough rain, so first irrigation was postponed. Halfway in June, it was dryer and hotter than expected so an irrigation planned for Monday was rescheduled to Saturday and both the researchers and drone operator only received this message on Saturday early morning. Less than one week later the opposite happened, when 20 mm/m² rainfall over night made that we had to cancel the planned irrigation and subsequent drone flight that was arranged on Friday.

The realities of running a farm got in the way

The irrigation need of a field cannot be predicted well in advance. It is a day-by-day assessment, made by the farmer accounting for the crop and the field, the weather and their other activities. Sometimes this is difficult to match the agenda with drone operators plans. In this OFE, when we received the second cancellation of the planned flight and irrigation, we agreed with the farmer that next time, he would irrigate anyway on the agreed day, regardless of the irrigation need, to ensure that we could carry out our research and find answers for the research questions we posed. 

This is asking more flexibility and engagement from the farmer than one should think, because when irrigating this one field when it is not necessary mean that the farmer is spilling water from his reservoir that he cannot use for another crop that needs it later, also it means that he is using his pumping capacity to irrigate one field that doesn’t need irrigation at the expense of another field with a higher irrigation need that day.

 So, it is much more complex than one would think. Being flexible towards the farmer and showing empathy and understanding for his situation is important and the best thing you can do, though, at a certain point you also need to assure that your research is not hypothised. It is important to find a good balance between empathy and flexibility on the one hand and insisting things getting done on the other hand.