Many combine operators are driving too slowly, losing too much corn and not getting out of their machines enough to check their losses.

That’s the opinion of Diss, Norfolk, combine driver trailer Tony Gardiner. Every year his New Life Training firm trains up to 60 combine drivers, usually in the early summer before visiting them during harvest to see how they are performing.

That typically involves a two-hour assessment including forward speed, losses (at the header, in the drum, over the sieves and in the straw), settings, safety and general combine-operating ability.

Each year’s best operator wins the National Champion Combine driver award. In 2007 that was James Fielden, assistant farm manager on Velcourt’s Vine Farm, Wendy, Royston, Hertfordshire.

James was driving a three-year old New Holland CR980 in two different fields during his assessment and managed to bag first and second prizes in the overall competition. In his best field he managed to trim total losses to just 20kg/ha, in the second best they ranged between 30 and 45kg/ha. In both cases he was harvesting 10.5t/ha Hereward wheat, very ripe but with damp straw, at speeds that varied between 7.2 and 8kph.

Impressive though this achievement is, it’s the high losses of some of the combines at the other end of the scale that are striking. While the average level of losses across all 54 combines tested, after training, was 59kg/ha, before training that figure was 246kg/ha.

“All makes and ages of combine are involved, but some of the biggest losses were among new 30ft machines,” he says. “They simply weren’t set right.” Some combines were losing 700kg/ha, with the very worst dropping more than 1000kg/ha on the ground.

At wheat prices of £150/t, the latter machine would have dropped 100t of wheat, worth £15,000, over every 100ha (250 acres) combined. It also means that the cost of the training is typically paid back in just 24 minutes of combining.

Mr Gardiner says that with combines getting bigger and bigger, it’s more important than ever to ensure that output is maximised and losses kept as low as possible. Average speeds were pushed up from an average of 4.4kph before training to 6.02kph after combining – a throughput boost of 40%.

And while drivers may be reluctant to spend valuable combining time scrabbling around in the stubble counting grains, such checks will pay back handsomely. A good alternative is to train corn cart drivers to assess losses on the ground.