At £2,000-2,500/ha, field drainage is expensive, admitts Warwickshire contractor and Nuffield Scholar Rob Burtonshaw, although he suggests the investment can be rewarded sooner than some growers believe.
“Drainage allows you to get onto the land when you want rather than when the water dictates, but the main point is that it increases yields,” he says.
Trials by the Field Drainage Experimental Unit showed that drainage boosted winter wheat output by 22.5%, and a Canadian scheme running from 1979-1999 put the figure at 38%.
Even at the lower figure, it would take only six years, with wheat at £200/t, to recoup a £2,250 outlay where the crop initially yielded only 8t/ha, he calculates. Given an expected life of 30 years, the annual cost was only £60-70/ha.
“Drainage is something the industry has forgotten about – it’s fallen down the priority scale. It’s been largely a case of ‘out of sight out of mind’. And as contractors we’ve failed to talk enough about its benefits.”
Ditching by contractor could be done for as little as £300/day plus transport costs, he adds.
The heyday of UK land drainage was in Victorian times, when the equivalent of £12bn was spent between 1850 and 1880, he notes. Even after the Second World War, 2m hectares were drained through grant-aided schemes. But after the withdrawal of grants in the mid-1980s the area drained each year dropped dramatically.
In 1987, consultants ADAS estimated that 20% of agricultural land in south-east England could be relying on 19th century schemes, and in the North the figure was thought to be as much as 70%. At the same time, it is suggested that 50,000ha a year were ceasing to function.
“A large percentage of that was because schemes weren’t being maintained, and today we’re nowhere near putting in 50,000ha a year. My educated guess is that it is under 10,000ha,” says Mr Burtonshaw.
Since then, farmers had tended to call on drainage contractors to deal with relatively small areas and often only in emergencies, he notes. “But our experience is that when people have some drainage done they usually want more.”
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