Appalling weather conditions have been blamed for the poor growing season, with wheat yields down 14% on the five-year average.
The gloomy situation has had a knock-on effect on livestock farmers who are now under greater pressure to buy-in winter feed.
NFU chief combinable crops adviser Guy Gagen said the 2012 harvest was one many would want to forget.
“The abnormally high rainfall across the UK since early summer this year has depressed wheat yields,” Gagen said.
“Without considerable investment by our farmers in recent years, the results for wheat could have been much worse.”
Arable farmer Andrew Pitts, who grows wheat and oilseed rape in Northamptonshire, said few farmers had come out unscathed this year.
“Oilseed rape has gone the same way as the wheat, down 20% to 25% due to the actual weight of the grains.
“The oilseed rape is all plant and no seed,” he said.
“With the wheat, the grains are tiny. Specific weights are in the middle 60s as opposed to the high 70s and early 80s which we had last year.”
Pitts, who finished drilling next year’s wheat last week, said the 2013 crop would also be adversely affected by the poor soil conditions.
“This is not just a harvest 2012 issue. It’s a harvest 2013 issue in a big way, due to the time of the drilling combined with a poor soil bed,” he added.
The pig and poultry sectors are expected to take one of the biggest hits as feed prices continue to rise.
Pig producer Andy Zambanini, who farms in the Brecon Beacons National Park in Monmouthshire, predicted soaring feed prices could force even more farmers out of business.
“Wheat prices have been high for a while now so producers were already under a lot of pressure but this could push many over the edge,” Zambanini said.
“We have had to drop our prices and when you’re paying £300 a tonne for pig feed, which is due to go up 25%, it’s not surprising people are selling up.”
However, the NFU survey found other major arable crops grown had performed well despite the difficult conditions.
Gagen added “Much of the 2013 rapeseed crop is now planted and up and farmers will be looking for further breaks in the weather to complete winter cereal crop planting.”
– UK Farmers Guardian