Autumn growth
In most autumns, a healthy beet crop will put on about 40t/ha between 1 September and late November. Average growth in September is about 18.5t/ha, in October 13t/ha and even in November it can be 7t/ha.
The main factors determining this growth are the weather and the health of the beet. Early in the autumn, moisture is a key determinant and dry weather will restrict growth. Later, frosts and severe cold will also have a major impact. The health of the crop is very much a result of the husbandry applied.
The aim should be to operate a just in time-in-time harvesting schedule to minimise post-harvest losses.
Nothing can be done to change previous inputs or influence the weather, so the main focus must be on good planning and management of harvesting, storage and delivery.
Harvesting schedules
These are important because much yield can be lost through poor scheduling. The first action should be to consider the health of all fields and assess their potential to grow well in the autumn. Poorly growing crops have much lower yield potential than healthy ones, and so should be targeted for an early harvest.
An important part of harvest planning is to ensure all those involved (for example, harvesting, loading and delivery contractors or partners) are fully aware of schedules and estimated field yields, so everyone can work together without surprises.
Harvesting
Harvester losses can be very large. In 2008, BBRO assessments recorded average harvester losses of about 2.5 t/ha, but ranging from just 0.3t/ha to as much as 7t/ha. Clearly, the latter is unacceptably high, but the difference between the best and average still equates to more than £50/ha. Large losses will also mean whole beet have been left behind and next year these can be a source of downy mildew and virus yellows for neighbouring beet crops.
All harvesters should have been fully serviced and checked well before the start of harvest and any worn parts replaced so there are no costly hold-ups during the season.
The main determinant of losses is the harvester driver. If the driver is new to beet harvesting or to the particular machine he is using, make sure he gets adequate training and backup, especially from the machine’s manufacturer.
BBRO offers a harvesting assessment service during the season. To arrange a survey, contact your British Sugar area manager, who is contracted to carry out this service. The results can then be used to help the harvester driver improve or, in some cases, to show him just how well the machine is operating.
Even the best harvester driver will struggle if soil conditions are poor. It is not always feasible but, where possible, try to organise for lifting to occur when conditions are good. In some cases, this may mean altering the harvesting schedule. If this is necessary, ensure all operators and contractors are given as much notice as possible.
Ideally, beet should be handled gently to reduce respiration and breakage losses, but this must be balanced against the need to ensure adequate cleaning of the beet. On light soils, most cleaning is carried out by the harvester; on heavier, wetter soils, harvested beet may need to be left so the soil on them dries before they are put over a cleaner loader. If beet are handled too aggressively, red bruising will be apparent on the roots. The harvester/cleaner should be adjusted immediately to avoid this.
Beet left in the field will continue to grow, albeit very slowly, after the end of November, but those placed in clamps will respire and lose sugar from day one. So the aim should be to operate a just-in-time harvesting schedule.
Storage
Until recently, the BBRO recommendation was to harvest all beet by early December to avoid risk of frost damage in the field. With climate change and improvements in harvesting efficiency, this is no longer a general recommendation.
Leaving beet in the field into the New Year does bring the risk of frost damage or waterlogging and this has to be weighed against the benefits of not losing sugar during storage. The system works well for growers on light soils that are not prone to severe frosts. But the risk of severe cold periods cannot be completely ruled out and there should be a back-up plan for rapid harvesting when such weather is forecast.
In an ideal world, the amount left in the ground into the New Year should be no more than can be harvested in three days before a severe weather warning. However, many take a risk and leave more than this and, in most years, this pays off.
The advent of large, self-propelled cleaner loaders has opened up possibilities for short-term storage of beet at the field edge for direct loading into lorries. This can reduce on-farm transport costs and open up options for beet growing on fields where concrete storage areas are not close at hand.
Clamps have been the traditional storage option, but are becoming less common. When beet are lifted and stored during warm weather, even for short periods, losses from respiration can be very high and so storage during such periods should be kept to a minimum.
If beet have to be stored in warm conditions, losses should be minimised by using A-shaped clamps, which provide the maximum surface area for ventilation.
Clamps used for storage later in the season should be no more than 2.5m high with the top levelled to avoid frost pockets. The sides of the clamps should be built using big bales as retaining walls, but placed on pallets for ground-level ventilation.
The clamp should remain uncovered if temperatures are -2C or above. All clamps should be free-draining to prevent waterlogging.