9 November 2001

Focus on beet storage to maximise returns

In an average winter, about 0.1% of total sugar is lost each

day that beet is in a clamp. With good management, the

loss after 30 days might only be worth £300. But this figure

can easily increase to £1500 if things go wrong

THE four main concerns with beet storage are respiration and ventilation, bruising and damage, frost and insulation and drainage and access, says British Sugars technical services manager Simon Fisher.

"The art of successful storage is to optimise these key concerns when they conflict with each other. At the start of the season, ventilation is important because the beet is still warm. But in December, preventing frost damage is paramount."

Respiration and ventilation

"Beet continues to respire when it is harvested," says Mr Fisher. "Respiration breaks down the stored sugars and releases heat and CO2. It takes place slowly at cool temperatures and speeds up as temperature rises.

"Beet clamps need adequate ventilation so respiration heat can escape." Avoid incorporating soil and trash into the pile because this imp-edes ventilation, he advises.

"Ventilation is critical at the start of the season when the weather is warm. Building piles of beet with a large surface area to volume ratio will help."

Bruising and damage

Damage to roots during harvesting provides ideal sites for the growth of bacteria, yeasts and moulds, so minimising damage to beet going into store is important.

"Handle beet carefully because bruised roots respire rapidly, which in turn creates more heat."

Frost and insulation

Beet freezes at -3C. Frosted and thawed beet cannot be processed, so stored roots must be protected if the temperature is likely to drop.

"Frost-damaged beet can cause the whole load to be rejected," warns Mr Fisher. "There are problems with invert sugars and dextran gums, both of which slow factory throughput."

Where beet will be delivered after mid-December, it should be in a clamp which can be easily insulated. "A clamp with a small surface area to volume ratio is required, so build rectangular piles with a flat or dome shaped top. An uneven top can double the amount of beet at risk from frost damage."

Choosing sheltered sites, away from north or east winds, can help reduce the risk.

Drainage and access

Building clamps on hard, smooth surfaces with a slope will provide drainage. "Site the base alongside a good farm road to allow access to both ends, so the first beet in can be first out."

Beet standing in water soon rots and cannot be processed. "There can be a problem when rain falling onto a clamp washes soil to the bottom and prevents water from draining away," warns Mr Fisher.

"Make sure the fall on the clamp site is sufficient. And dont forget that poor drainage means vehicles wont be able to get to the site in wet weather."

Building the clamp

Clamps should be built on concrete or other smooth, hard surfaces with a slope laid to a minimum fall of 1 in 80 to allow water to drain.

"Clamping onto a soil base is only acceptable for short-term storage, early in the campaign and in dry weather," says Mr Fisher. "Only a coarse sand soil will drain well enough to carry the traffic needed to build and empty a clamp."

Concrete bases are best and he suggests the area should be large enough to store about half the crop. "Store the beet no more than 2.5m high and allow between 0.8 and 1sq m of base area for every tonne of beet to be stored."

Straw is the traditional insulation material and big square bales make good clamp walls. "Stand them on pallets, one or two high, to help with ventilation. Small bales are good for blocking gaps in frosty or windy weather.

"Dont cover the top of the clamp unless frost is imminent. Use a cover that can be put on and taken off quickly. Straw works if the clamp is first covered by a net, but poly-propylene sheets are more convenient and should last several years."

Where sheets are to be used, the clamp top should be slightly dome-shaped so the covers do not collect rain. "They protect the beet but should still allow some ventilation."

Where possible, clamps should be built with high lift or dump trailers. "These can build the pile to about 2.3m without using a telescopic handler, which saves money and prevents damage.

"And dont push the beet up high with a loader bucket because ventilation will be restricted. Its better done with a dump trailer or telescopic loader."

The top of the clamp should be levelled to minimise the number of exposed beet. "The exception to this is early in the season, when exposure will help to get rid of heat." &#42

CLAMPMANAGEMENT

1 Site Build on a solid, well drained base, close to good road access and sheltered from freezing wind and frost.

2 Beet condition Store only healthy beet, free from rots or frost damage, and minimise bruising and broken roots with careful harvesting and handling.

3 Ventilation Keep soil and trash out of the clamp so that ventilation is unrestricted. Build piles of beet with a large surface area:volume ratio at start of season.

4 Clamp base Use concrete or other smooth, hard surface with a slope. Only clamp onto a soil base for short-term storage.

5 Drainage Lay bases with a minimum fall of 1 in 80 to allow water to drain.

6 Clamp height Store beet no more than 2.5m high.

7 Insulation Straw bales make good clamp walls. Stand on pallets for ventilation and be prepared to cover inlets when frost is forecast.

8 Covers Only cover the clamp when frost is imminent, using either straw or polypropylene sheets.

9 Clamp tops Level the top of the clamp, except in early autumn. An uneven top will double the amount of beet at risk from frost damage.

10 Safety Use a ladder. Clambering up and down the face of the clamp is dangerous.