A crucial fortnight is set to determine harvest yields and quality amid one of the most variable seasons for a decade.

With combines well into oilseed rape and barley crops, attention is turning to wheat – especially bushel weights. While some farmers are reporting good crops, concern over low specific weights has seen many loads rejected.

In Kent, three out of four loads were falling short of milling wheat standards, said Weald Granary store manager John Smith. A similar situation is emerging in Norfolk, with 40% of crops failing on bushel weights at Aylsham Grain.

The Met Office said a North West/South East split looked likely to dominate the weather this coming week. The North and West will be mostly unsettled, often with strong winds, and a mixture of sunshine and showers at first, with some more persistent rain later next week.

It will be less showery in the South and East. But unsettled weather is expected to return to all areas towards the end of August, with some short-lived drier and brighter periods. Daytime temperatures are forecast to remain largely around average or a little below.

Jack Watts, HGCA senior analyst, said: “The next two weeks will be critical for the UK wheat harvest, considering we are already 10-14 days late. An unsettled forecast is going to raise concerns – especially as more wheat reaches maturity.”

In many cases, grain was dry enough to harvest but the straw underneath remained green. “Variable is the word when it comes to yields,” said Mr Watts. “Some growers have been extremely disappointed, but others have been very happy, considering the circumstances.”

NFU combinable crops chairman Andrew Watts said travelling conditions had improved over recent days. But much ground remained pretty wet. “The frustration is that people aren’t getting a good run at things. The last properly dry year we had was 2003.”

A long, wet growing season, with no dry spell at harvest, also had implications for following crops and autumn cultivations. “If this sort of weather carries for another week, you have to question how much oilseed rape will be successfully planted after wheat.”

Martin Savage, trade policy manager at Nabim, said it was too early to paint a general picture because only about 5% of milling wheat had been harvested. But growers should avoid comparisons against last year’s exceptionally good harvest, he added.

Proteins were closer to the five-year average and early Hagbergs were good. But low specific weights were resulting in lower quality. “It tends to be a general pinching of the grain rather than a shrivelled grain.”

Harvest was shaping up to be more weather dependent than usual, agreed Mr Savage. “A week’s good weather could make all of this academic.

“Doom, gloom and panic is easy to create – the old adage you only know what you’ve got when it is in the barn remains as true as ever.”

Johann Tasker on G+