Plant Protection Robots in Vegetable Farming: Labour, Costs, Social Aspects and Ecology

A hoeing and spot-spraying device enables huge savings in the use of plant protection products. Although costs are higher than for conventional plant protection devices, motivated farm managers give this innovative technology genuine prospects for the future.

Digital technologies in plant protection are meant, inter alia, to support farmers in the targeted use of plant-protection products (PPPs) via precise application methods such as so-called spot-spraying, thereby reducing the amount of PPP applied.  In a project supported by AgriQNet*, a camera-controlled plant-protection device was developed for vegetable production. The tractor-drawn attachment not only applies PPP via spot-spraying technology, but can also hoe in and between crop rows, rendering herbicide applications unnecessary. Pesticide savings of around 75% are possible.

Case study

In a case study conducted on a pilot farm with field-grown salad crops, Agroscope investigated the potential economic, ergonomic and ecological benefits of an innovative technology such as a plant-protection robot for a farm, as well as examining the qualities required in a farm manager for the successful use of the technology. In time studies taking place during the use of the prototype in the field, workflows were documented and the working-time requirement for a standardised plot was modelled according to labour economics methodology. The calculation models also served to investigate changes in technical factors such as driving speed and working width, as well as their effect on the time requirement. Prototype cost-effectiveness was investigated in a partial-costs analysis and a comparison with a conventional plant-protection strategy. In an in-depth interview, the farm manager commented on various aspects of personal attitude which, according to the literature study, positively influence the adoption of the technology.

Higher time requirement

The prototype requires the producer to budget for significantly more time than conventional methods such as field-spraying and hoeing device. The working-time requirement for plant protection rises from 0.65 h/ha with the conventional method to 3.83 h/ha with the prototype. The reasons for this are mainly technical in nature – the lower driving speed of 1.2 vs. 6.5 km/h, as well as the smaller working width of 1.5 vs. 3m. There are also changes in the workflow, however. At present, two people drive to the plot in order to enter the settings on the spray frame of the prototype at the start of work.

Plant protection costs 50% lower, machine costs up

Thanks to the digital application technology combined with the hoeing between and in the crop rows, expenditure for PPP in salad crops can be reduced by 50%, from CHF 829 to CHF 411 per hectare. On the other hand, the robot’s purchase price of CHF 135,000 drives up the machinery costs and currently prevents the spot-spraying technology from being cost-effective. If, however, the robot were used on 80 ha instead of just 20 ha per year, i.e. on a larger farm or on more than one farm, costs could be reduced by 45%, i.e. from CHF 4625 to CHF 2757 per hectare. Further technical developments such as a higher driving speed of 2 km/h or a doubling of the working width to 3 km also achieve significant cost reductions.

Proactive, tech-savvy farm management essential

One focus of the case study was the examination of factors favouring the successful introduction of new technologies, in particular the attitude of the farm manager. Besides the general attitude to technological developments and digitalisation, a willingness to learn and to take risks as well as skill in handling new technologies and in dealing with difficulties were key. In the farm manager’s opinion, a tech-savvy attitude and a basic interest in digital developments are essential. Straightforward, readily available technical support also plays a key role.

* AgriQnet: A network for the promotion of innovative agricultural projects, comprising the Swiss Farmers’ Union, Swiss Food Research, the Quality Strategy Association and the Federal Office for Agriculture.


  • A sensor- and camera-controlled hoeing and spot-spraying device can save 75% of the pesticides and 100% of the herbicides normally used over the course of a salad-crop season.
  • In its current form, the prototype requires both higher investments and a higher labour input per hectare than conventional plant protection devices.
  • There are new prospects for the use of the prototype if it can be used to replace manual hoeing, as for example in organic farming.
  • The use of this new technology could also prove attractive if consumers are prepared to pay a premium for more-environmentally-friendly production or if the State specifically compensates growers for these ecological services.
  • In addition, the enthusiasm of the farm manager for technical developments and good technical support are essential for successfully introducing new digital technologies in practice.
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