22 December 2000

Myths must be dispelled to end poor practice

COMMON misconceptions are leading to poor grain storage on UK farms, says a leading expert.

Cooling grain is top of the "Key Myth" list CSLs Ken Wildey has drawn up (see below). Growers are not cooling grain soon enough or cold enough, he says.

"The message is get it cold, cold, cold. I mean very cold."

Concerns that the cooling process is expensive stop some from blowing grain adequately, and misunderstandings about when the conditions are right to do so are also widespread. "People hear the fans running and they think money. But the cost of cooling should only be about 5p/t and it can be as low as 2p/t if you use night-rate electricity and have a good set-up," he says.

Mild, misty or rainy nights are fine for blowing grain too, provided grain is 4-6C warmer than ambient air. The fans warm air slightly, dropping the air humidity by about 8%, and then the cooler air meets warmer grain so humidity drops further, he says.

"There is no such thing as saturated air from a fan."

Simple differential thermometer systems should be fitted to switch fans on and off, making the most of suitable cooling conditions. "These typically cost £50-£200 a store, but that can be offset by savings in electricity. Winter is the time to be thinking about fitting such devices ready for next harvest," he says.

Cooling should start immediately after harvest, taking grain below 15C within a fortnight and 12C shortly after that. Below 12C grain beetles and weevils stop breeding but mites and fungi are still active, so the long-term target is 5C. At that mite and fungal growth is all but eliminated and relative humidity is also reduced. "The only exception to the 5C target is malting barley. Maltsters do not like to receive grain below 10C," he says.

Complacency about storage can come from pre-harvest cleaning as no treatment can guarantee to remove residual infestations. "You have got to assume there will be survivors and be doubly diligent in cooling and drying grain."

For a serious mouse infestation many expect anticoagulant rat-bait to do the job, but control is limited, he warns. "Calciferol is the material for mice, but it is not effective on rats Unfortunately there is not a one-size-fits-all solution."

Last on Dr Wildeys myth list is oilseed storage. Few growers get to grips with the fact that for safe storage fan capacity must be doubled, or depth halved, to achieve adequate ventilation in storage designed for cereals, he maintains. Contract moisture specification is also misleading.

"Oilseed rape has to be dried to 8% maximum as moulds and mites will grow at 9%. The approval for surface treatment with insecticide has been revoked," he adds. &#42

"Chill out…" Cooling is the key to good grain storage, yet many growers hold misconceptions about best practice, says CSLs Ken Wildey.

TOP 5 STORAGE MYTHS

Theseareall wrong!

&#8226 Cooling is costly so 15C will do.

&#8226 Grain cannot be cooled or dried in damp weather.

&#8226 Structural treatments control residual infestations.

&#8226 Anticoagulants control mice.

&#8226 Oilseed storage needs are similar to cereals.

Reject evidence

A recent rise in rejections of grain delivered to ports for export supports Dr Wildeys suggestions that there is much room for improvement in storage practice. "One trader disclosed that 35% of grain destined for a 5000t cargo was rejected because of high moisture content," says British Cereal Exports manager Rachel Walker.

The HGCA Grain Storage Guide is free for levy payers, £25 to non-levy payers. Tel: 020-75203949 or visit www.hgca.com