AN AUTOMATED solution to lettuce harvesting is about to be launched as a possible solution to the ongoing horticultural labour shortages in the UK, with a prototype of the robotic harvester being developed for field trials this September.

Agri-tech and machinery experts at Grimme, Agri-EPI Centre, Image Development Systems, Harper Adams University and The Centre for Machine Vision at the University of the West of England, Bristol have joined forces with two of the UK’s largest lettuce growers, G’s Fresh and PDM Produce, in the new Innovate UK-funded project to automate lettuce harvesting.

With growing pressures to attract and retain pickers, growers are reportedly keen to adopt commercial robotic solutions as a means of reducing their reliance on seasonal labour.

Lettuce is the UK’s most valuable field vegetable crop and around 99,000 tonnes were harvested in the UK in 2019, with a market value of £178 million. But access to reliable seasonal labour has been an increasing problem, exacerbated by Brexit and Covid-19 restrictions. Early indications are that a commercial robotic solution could reduce lettuce harvesting labour requirements by around 50%.

Vegetable specialist at lead project partner Grimme, Thom Graham, said: “One of the greatest challenges facing the horticulture sector is sourcing sufficient seasonal labour to conduct their harvest commitments in a timely manner. In addition, rising cost of labour with no increase in retail price has squeezed margins. Growers are looking at solutions that can reduce labour input costs and maintain their resilience in the sector and we hope our expertise can help.”

The project will adapt existing leek harvesting machinery to lift the lettuce clear from the ground and grip it in between pinch belts. The lettuce’s outer, or ‘wrapper’, leaves will be mechanically removed to expose the stem. Machine vision will then identify a precise cut point on the stem to separate lettuce head from stem.

Managing director of Farming at PDM, Dermot Tobin, added: “For many decades our business has relied on seasonal labour for harvesting lettuce. Nearly all the lettuce you see on UK supermarket shelves is cut by hand. Sourcing labour is getting really challenging and with wage inflation rising far quicker than returns to growers, margins are really tight. Our industry needs to embrace robotic technology to reduce our reliance on labour so being involved in this project is of the utmost importance to our business.”

Innovation and research project manager of G’s subsidiary Salad Harvesting Services Ltd. Richard Ellis, concluded: “The process of lettuce harvesting has continuously evolved over the past 30 years, with harvest, packing, date coding, boxing and palletising all completed in the field, within minutes of the crop being cut. The cutting process of an iceberg is the most technically complicated step in the process to automate. We are encouraged to be involved and see the results of this project which offers the potential to reduce reliance on seasonal labour.”