A weak harvest has contributed to a £3.3m loss at grain supplier Openfield.

Announcing its results for the year to 30 June 2017, the British farmer-owned co-operative said lower 2016 harvest volumes and market dynamics relating to milling wheat premiums had made for “very tough” trading conditions.

The co-operative made a pre-tax loss of £3.3m, down from a £1.7m profit in the previous year. Grain volumes fell to just under four million tonnes, and group revenue fell 8% to £655m.

Owned by almost 4,000 farmers, Openfield supplies brands including Warburtons and British Quality Pigs. In addition to marketing grain for farmers and grain stores, it distributes fertiliser and manufactures and sells seed.

Despite the loss, Openfield said the business had performed well against its priority to “deliver service and value to members”.

It added it had outperformed the market in terms of returns to its farmer members, and grew its share of the UK domestic market.

“The results reflect very tough trading conditions coming out of a small 2016 harvest,” said Openfield chairman Philip Moody.

“Openfield has always managed its own profitability to strike a balance between maintaining our financial strength and balance sheet and supporting our members in challenging marketing years, which we continued to do last year.”

He added that membership of the co-operative had grown by 19%, and that £250,000 had been invested in a seed production plant and improving collection and delivery efficiency.

Openfield said its core financial strength remained strong, with net assets reported at £18.5m, no core borrowings and a surplus working capital of £4.9m, although this was down from £7.7m in 2016.