A late crop harvest is nearly finished, with yields well up on last year due to wetter weather.
The Foundation of Arable Research held a series of round-up meetings last month to survey farmers on the past season.
Research co-ordinator Nick Poole says some farmers in Canterbury, the main grain and seed growing region, have crops yielding 30% more than last year.
But he says they had to deal with the extra expense of drying their grain. And in some cases, the crops were too lush.
Mr Poole says the late harvest will affect this season's crops. Another implication of a wet and late harvest is an increased level of dormancy in grain and weed seeds, so farmers should be aware that they may germinate more slowly.