The UK wheat crop has turned out even worse than previously thought, farmers said, pegging the yield at the lowest in more than 20 years, and warning of the impact on food and feed prices.

The National Farmers' Union said the UK wheat yield had fallen to levels "not seen since the late 1980s", thanks to volatile weather which followed early-2012 drought with "persistent and occasionally torrential" rain, which brought the country its wettest summer in a century.

The poor harvest has fed through into weaker farmland prices, besides raising expectations for wheat imports, with some market talk that the UK could, unusually, turn net importer in 2012-13.

"The abnormally-high rainfall across the UK since early summer this year has depressed wheat yield," said Guy Gagen, the NFU's chief combinable crops advisor.

The union pegged the yield at 6.7 tonnes per hectare, below the range of 6.8-7.2 tonnes per hectare which consultancy Adas has estimated, in reports to the HGCA crop bureau.

In fact, the wheat yield in England, which makes up the great bulk of the UK crop, fell to 6.7 tonnes per hectare in 1992

Better for rapeseed

The NFU was more downbeat on the UK spring barley yield too, pegging it at 5.0 tonnes per hectare, below the Adas range of 5.1-5.3 tonnes per hectare.

However, the union was sanguine on  barley quality, saying that the crop was "good for malting".

And it was optimistic over rapeseed too, pegging the yield at 3.6 tonnes per hectare and oil content as "average".

Adas said last week, in its final harvest report, that the "oil content of oilseed rape was low at 40-44%".

Threat to livestock farmers

The NFU added that, with the "poor" UK harvest coinciding with weather hits to crops in some other regions, including drought in the US and Russia, the country faced "the prospect of relatively high commodity [price] levels through to 2013".

Besides the impact directly on consumer of higher grain costs, pig and poultry farmers were "already struggling with higher feed costs" which are threatening to prompt some producers to quit.

The poultry industry faced "the risk of critical mass in domestic production eroding", NFU corporate affairs director Tom Hind said, warning that the "unprecedented volatility that we have been experiencing in feed costs recently [is] likely to stay.

"Feed is the single biggest cost to poultry producers, and many are reporting to me the significant outlay they are having to make to purchase feed compared to last year."

Potato setbacks

After a break in early September, the rains have resumed to interrupt autumn sowings and the lifting of the potato crop, of which 51,000 hectares had been harvested as of Friday, equivalent to 43% of the total, compared with a level above 60% a year ago.

"The recent heavy downpours that are capping off the wettest spring and summer in over 100 years continue to impact the harvest," Shore Capital analyst Phil Carroll said on Wednesday.

The slow development of potatoes during the dull summer has also prompted many growers to hold off harvesting, hoping for late boost to yields, although the harvest looks like being one of the lowest in recent history nonetheless.

Produce Investments, owner of the Greenvale potato merchant, estimates the crop hitting its lowest since 1976, as Agrimoney.com revealed last week.

Low crop expectations have manifested themselves in a rise in UK prices for free-buy potatoes, those not grown under contract, to £271.04 a tonne as of Friday, up 3.6% in a week, and more than triple levels a year ago, according to the British Potato Council.

"With adverse weather continuing to restrict lifting and many [farms] now concentrating on loading into store, supplies remained short with prices steady to firm," the council said.