Heavy cost of a careless
By Robert Harris
CARELESS sugar beet harvesting could cost each grower thousands of pounds in profit, this season. The problem is so widespread that British Sugar is stepping up efforts to curb it.
A BS survey conducted in 1992 showed national losses of 4t/ha (1.6t/acre), some 10% of the crop. Even in near-perfect lifting conditions two years later 3.5t/ha (1.4t/acre) of roots remained in the field.
"Those figures were quite alarming," says agricultural development officer Stephen Brown. "There is certainly room for improvement. The best 30% of harvesters in the 1994 survey achieved 2.1t/ha. Growers can realistically set a target of 2.5t/ha; even less in a good season."
That will save them an average of £44/ha (£17.80/acre) at this seasons contract price, says Mr Brown. Many stand to gain much more. "In one field we tested, 7.5t/ha was being lost. Over 50ha that amounts to £11,000."
This season, BS will visit 150 of the biggest growers and contractors at random across the country to assess field losses, pinpoint the causes and suggest remedies (see box).
To date, the free, voluntary Quality Harvesting Programme has been well received, he says. "There have been no refusals. Its very difficult for growers to assess losses, and they recognise the test gives them a benchmark to work to and maintain."
Growers not chosen this year can still do much to cut losses, says Mr Brown.
Although too late for this season, ensuring a level seed-bed helps enormously, he notes. "About 65% of the crop is now harvested by six-row machines. Given the width of the lifting mechanism, level ground has a marked effect in reducing the amount of root left in the ground."
Matching the lifting mechanism to soil type will reduce root breakage, he advises.
"Skid and disc systems should be confined to light and medium soils. On heavier ground use powered shares.
"These vibrate the beet out of the ground, lessening the chance of breakage. And more soil falls off, so you dont have to clean it so hard in the harvester."
Incorrect or worn lifting mechanism settings exacerbate the problem. "Stick to manufacturers tolerances," says Mr Brown. As a guide, if 90% of the beet in the trailer have no more than 4cm (1.6in) missing from the bottom of the root then losses are about 2t/ha (0.8t/acre). "Any more, and losses escalate."
Extra care needed
Small roots, especially common this season, need extra care. The gap and angle between skid and disc may need closing, as will the distance between shares. On machines with oppel wheels, gaps between the wheels should be checked, and the release point may need altering.
Filler spokes may also be needed to avoid roots falling out, he adds.
Forward speed of 3-3.5mph should be maintained to keep the machine full. If roots still fall out of the harvester, use smaller webs or fit alkathene pipe, says Mr Brown.
If it turns wet, operators should slow down and set the lifting mechanism as high as possible. This will cut soil intake and reduce the need for aggressive cleaning. Higher turbine speeds, wider gate settings and more web agitation may still be needed, but beware of losses and bruising, he advises.
Damage to beet, especially if it is to be stored later in the season, must be minimised, warns Mr Brown. Harvested roots will try to repair cuts and scrapes, raising the temperature in the damaged area. That increases respiration losses and warms the heap further, compounding the problem and encouraging fungal rots.
Big drops should be avoided, he warns. "Treat beet like potatoes. Lower the side elevator as much as possible when unloading into an empty trailer and maintain the minimum clearance as the trailer fills."