Different approaches to sustainable sourcing from farms were revealed by food manufacturers and retailers at the CropWorld event.
Marks and Spencer's technical manager Hugh Mowat admitted that looking within the company's own business for sustainability improvements was far easier than taking it down the supply chain and out to farms.
"We've started the process with farmers by identifying risk factors, such as soils and water, and establishing some best practice guidelines."
These guidelines have been criticised, he acknowledged. "They were judged to be too simple, so we had to go away and come up with something more detailed."
The next steps have been to benchmark progress and support innovation with funding. "And there have been successes. We have a target for all our produce to be 100% residue free by 2020, but we already have that with our labelled Jester tomatoes."
Similarly, Project Minimise is working to reduce residues in apples and grapes, while Pacesetter Projects have been successful with the recent launch of autumn asparagus, he reported.
Sarah Miskell of Warburtons said that the company's long term partnerships with farmers were allowing both parties to develop the sustainability agenda.
"It's working progress," she said. "We liken it to being on a journey. We're working together on ways to reduce nitrogen fertiliser, optimises water use and cut down on waste."
A farmers' forum is operated by Warburtons, with meetings held three times a year. "By sharing experiences and highlighting new research, we're all learning how to grow great quality wheat using fewer resources and with less impact."
Rozanne Davis of Innocent said that the company had decided not to go down the certification route with its growers, with the exception of the Rainforest Alliance standard on bananas and pineapples.
"We have set out our stall and made our expectations known," she commented. "But we haven't used audits or assurance schemes."
Innocent has mandatory, required and desirable standards, she reported. "These can be different for small and large farms and may vary according to country. We tailor our approach, which is why certification isn't right for us."
Partnerships are entered into where they're likely to be beneficial, admitted Ms Davis. "They allow us to punch above our weight. They've helped with reducing the chemical loading in Indian mangoes and the water footprint of Spanish strawberries."