Maize is increasingly being grown on marginal sites, as dairy farmers try to exploit earlier maturing varieties to produce more milk from forage.

However, the difficulties posed by such sites make appropriate nutrient supply essential.

And while most farms located south of a line drawn between the Mersey and the Humber and below 400ft above sea level can grow maize with few problems, site selection is crucial elsewhere.

Exposed fields are unsuitable, as windy conditions can cause plants to dehydrate, which reduces yield.

But many farmers regularly harvest good crops of maize on marginal sites.

One estimate suggests 60% of plantings in Wales are on far from ideal fields.

“It is important to assess the capability of the site and the farmer,” says Agrovista agronomist Elfed Holloway.

“In marginal areas growers need little more than organic manures to achieve the yield potential.

“Knowing the crop’s nutrient requirement is important, but an accurate assessment of how much manure and bagged fertiliser should be used is impossible unless manures and soils are analysed.

“There is often a temptation to see maize land as a dumping ground for slurry, but excessive applications must be avoided as they damage the crop and the environment.”

Mr Holloway adds that using too much inorganic fertiliser is expensive and will not produce an economic response.

Norfolk based independent consultant Simon Draper, who works closely with the Maize Growers Association, warns clients they will waste fertiliser unless they properly calculate the benefit of the manures applied.

About 41t/ha (17t/acre) or 93,000 litres/ha (8500 gal/acre) will supply 240kg of potash/ha and all the phosphate the crop needs.

“Oversupply of nutrients will make the crop more lush and leafy, which can delay maturing by as much as two to three weeks and put the crop at risk in marginal areas,” Mr Draper warns.

He suggests that 122kg/ha (1cwt/ac) of monoammonium or diammonium phosphate could be applied as a starter fertiliser to encourage growth and improve yield and harvest date.

bobdavies@agrinews.fsnet.co.uk