This blog post is based on the 13th Practice Abstract from the second batch of Farmtopia Practice Abstracts.
Reducing herbicide use while maintaining crop yields and farm profitability is an important challenge for European farmers. Precision spraying technologies can help by targeting weeds rather than treating an entire field, but adopting them often means investing in new machinery.
For small and medium-sized farms, replacing an existing sprayer can be a major expense. Farmtopia therefore explored whether precision spot spraying could be integrated into machinery that farmers already have.
Bringing precision spraying to conventional sprayers
Within the Farmtopia project, ARVALIS evaluated a retrofit spot-spraying system developed by CarbonBee. Instead of requiring farmers to purchase a completely new sprayer, the system can be installed on conventional spraying equipment.
The technology uses optical sensors to detect weeds in real time. When weeds are identified, only the nozzles needed to treat the affected areas are activated, while weed-free parts of the field remain untreated.
The system was tested under real-world growing conditions on corn and wheat at two French farms, representing their respective regions.
The evaluation focused on three main areas:
- How accurately the system could detect weeds
- How reliably the sprayer could activate the correct nozzles
- What the technology could mean for farm economics and environmental performance
What did the tests show?
The results demonstrated the potential of targeted spraying to significantly reduce herbicide use.
In maize, the weed detection algorithm achieved a detection rate of around 70%, while missing only 2.5% of weed plants. In grassland, blackgrass detection reached 92%, with only 1% of plants missed.
Wheat presented a greater challenge because weeds can closely resemble the crop itself at certain growth stages. However, the results for wheat continued to improve during the testing.
The transfer from weed detection to actual spraying was highly reliable. The system correctly opened and closed the appropriate nozzles in 90 – 99% of cases.
Depending on the level of weed infestation, spot spraying reduced herbicide use by 75 – 99% in the most infested fields.
What does this mean for farm economics?
The assessment also looked beyond technical performance.
Economic simulations showed substantial reductions in herbicide costs and in the Treatment Frequency Index (TFI), with reductions of approximately 6–14%. At the same time, the net farm margin remained almost unchanged, despite slightly higher mechanisation costs and working time.
Environmental indicators, including greenhouse gas emissions and energy consumption, changed very little.
These results suggest that the main value of the technology lies in reducing unnecessary herbicide applications while maintaining broadly comparable economic performance.
When does spot spraying work best?
Spot spraying is particularly useful in fields where weeds are unevenly distributed.
When infestation occurs in patches, large areas of a field may be weed-free. Treating only the areas where weeds are present can therefore avoid applying herbicide where it is not needed.
Farmers considering the technology should ensure that the system is properly calibrated and adapted to their local field and crop conditions.
The initial investment is another important consideration. For farms that cannot justify purchasing the equipment individually, machinery-sharing groups, cooperation with neighbouring farms, or contractors and service providers can offer alternatives.
This can make precision spot spraying accessible without requiring every farm to invest in its own retrofit system.
Making precision crop protection more accessible
SThe Farmtopia testing shows how retrofit technologies can help bring precision agriculture to farms without requiring a complete replacement of existing machinery.
By combining real-time weed detection with targeted nozzle activation, farmers can treat affected areas while leaving weed-free zones untreated. For fields with patchy weed pressure, this can offer a practical way to reduce herbicide use while continuing to work with conventional spraying equipment.
Based on Farmtopia Practice Abstract 13
This blog post was created from Practice Abstract 13: “An IoT-Based Precision Spot-Spraying System for Targeted Crop Protection”, part of the second batch of Farmtopia Practice Abstracts.
Publisher: ARVALIS
Authors: Harel Camille, Desbourdes Caroline
Contact: c.harel@arvalis.fr