Harvest frosted beet on demand

Michael Hennessy

The frost over the weekend reminded us of the temperatures we experienced around the first week of January - although many growers don't need too much reminding as they continue to deal with the consequences of that cold snap.

Apart from growers looking at heavy losses in potatoes, vegetables and nursery stock, many tillage growers are looking at losses from fodder beet. During that period of frosty weather soils were frozen to a depth of 10-15cm (4-6in), freezing all material under the ground to that depth. The growth habit of fodder beet differs from variety to variety in terms of the amount of root exposed on top. Up to one third of the root on top can be exposed on many varieties.

The frosty weather has had two effects on beet left in the ground. Firstly, most of the leaves have died off and the chances of pulling the beet with a belt puller are not great. Secondly, the over-ground portion of the beet that was frozen is now defrosted and has gone soft.

As many growers (and all county councils) will know, when water freezes it expands and bursts water pipes. The process of water expanding when freezing takes place at the smallest level within the plant. As fodder beet has a dry matter of somewhere between 15-18pc there is a lot of water (82-85pc) to freeze. As the water freezes within the root it bursts the cells, resulting in a softening of the root when defrosted.


In the past we were used to dealing with lightly frosted beet which would try to repair itself, therefore extending its shelf life. However, badly frosted beet probably won't have the capacity to heal itself as the majority of cells have broken down and are not functioning.

This breakdown (resulting in soft beet) renders the beet susceptible to attack from bacteria and fungi. This natural breakdown will result in blackened beet, and the speed of the breakdown will depend on the temperature where the beet is stored. The longer the weather stays cool, the slower this degeneration process will take.

Harvesting and storing badly frosted beet in a clamp could be a mistake, as heating within the clamp can often be a problem. This heat would then accelerate degeneration resulting in increased losses.

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Some people are considering harvesting frosted beet then chopping and ensiling this beet in a pit. This option also presents difficulties as beet is low in dry matter and the freezing process has deteriorated existing fibres making the chopped material more liable to turn into liquid.

Trapping this material in the pit will be a problem, and the risks of substantial run-off are very high. Pitting this material poses another problem -- if significant rotting has already set in then good preservation will be difficult, and this may also increase spoilage at feed out.

At the moment soil temperatures are generally running around 2-4°C or about the same temperature as a fridge. The cool soil will help to slow breakdown of beet, therefore harvesting beet on demand would appear to be a reasonable option.

Harvesting will present difficulties and many growers will be forced to harvest with squeeze wheel-type machines. Extra stones and increased soil can be a feature of these machines, especially in very wet conditions.

Due to the transition in the structure of frosted beet, a change in how it is fed is required, according to my colleague Dr Siobhan Kavanagh. As a consequence of cell breakdown in frosted beet, the sugar within the cell becomes more readily available. Frosted beet is also higher in oxalic acid. Both the sugar and oxalic acid can increase the incidence of scour and sicken animals.

Therefore, Siobhan recommends increasing the roughage content of the diet when feeding thawed beet. She also advises only chopping beet as it is required. There is no problem grazing thawed beet, which has a slightly blackened crown when the leaves are intact. However, do not graze it when it is frozen.


Meanwhile, grain prospects for this year and the potential of share farming will be two topics covered at this Thursday's Teagasc National Tillage Conference in the Seven Oaks Hotel, Carlow, starting at 10am. Other subjects on the agenda include shifts in septoria populations, disease control in wheat and soil organic matter testing.

Irish Independent

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