Farming robots show potential for onion and lettuce cultivation

Agriculture faces growing demand for food while needing to reduce greenhouse gas emissions and resource consumption. Rising input costs and labour shortages add to these challenges. Battery-powered farming robots could help by performing tasks autonomously, applying water, fertiliser, and crop protection agents more precisely, and partially replacing diesel-powered machinery.

A modelling study by researchers from the University of Münster and the University of California, Davis (USA), found that battery-powered farming robots showed particularly promising results for onions and lettuce, especially in organic farming, where weed control without synthetic herbicides requires considerable labour and expenditure.

Depending on the scenario, modelled cultivation costs ranged from 76 per cent below to 17 per cent above reference values from scientific literature, with conventional harvesting costs added for comparison. Greenhouse gas emissions were generally within or below reported ranges.

Variable inputs, including seeds, seedlings, water, fertiliser, herbicides, electricity, and labour, accounted for 72 to 90 per cent of cultivation costs and 72 to 95 per cent of greenhouse gas emissions. Water, seeds, seedlings, and fertiliser were particularly relevant to emissions.

"A robot does not automatically make agriculture more sustainable. The modelled benefits arise when its precise deployment enables resources to be saved," explains Professor Stephan von Delft from the Institute of Business Chemistry at the University of Münster.

"Policymakers and farmers should therefore test and promote applications in which autonomous systems can reduce not only labour requirements and agricultural inputs, but also greenhouse gas emissions."

The researchers examined strawberries, onions, lettuce, and peanuts under organic and conventional cultivation systems. Each scenario modelled a battery-powered robot weighing approximately 200 kilograms, performing soil preparation, sowing, weed control, irrigation, and fertilisation.

Costs and emissions per kilogram of harvested produce were calculated using scientific literature, technical specifications of existing robots, and the life cycle assessment database ecoinvent.

Harvesting was excluded from the robot model because harvesting methods, mechanisation, and labour requirements vary between crops. Conventional harvesting costs were subsequently included for cost comparisons, while potential harvesting-related emissions were assessed through sensitivity analysis, which examines changes resulting from different assumptions.

According to the researchers, this is the first study using a consistent modelling framework to assess the economic and environmental impacts of battery-powered agricultural robots across multiple operations, crops, and cultivation systems.

Compact robots could be suitable for small and medium-sized farms, particularly for onion and lettuce cultivation in organic systems, as well as shared use among farms or cooperatives. However, investment decisions would require adapting the model to local conditions using farm-specific data.

"The results can help farmers, manufacturers and policymakers identify promising applications," adds Stephan von Delft.

For more information:

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