Potato growers urged to repair soil

Potato growers who fear soils earmarked for next season’s crop have been damaged by the sodden cereal harvest should consider rectifying that damage as soon as possible.

Speaking at a recent Potato Council technical event near Norwich, Cambridge University Farms’ Mark Stalham urged growers to examine the extent of soil damage in the autumn and plan repair strategies accordingly.

“You need to dig a hole, find out what the soil condition is like at depth and work out how best to tackle what you’ve got.”

It could be beneficial to take action in autumn, rather than spring, particularly if the damage was below subsoiler depth, he said.

“Soils are drier at depth in the autumn so running a tine through at this time could give a great deal of sideways fracturing and improve compacted layers.”

The tine would need to be pulled through just below the compacted layer to give the maximum effect, he explained.

However, this was not necessarily the best course of action for all soil types. “For example, if sandy soils are subsoiled in the autumn they can slump badly over the winter and impede drainage channels.”

But for most growers, waiting until the spring to carry out deep remedial treatments was more risky. Subsoiler benefits could be reduced and the operation might even have adverse effects, he explained. “Soil will be topped up with water over the winter and could be too wet at depth to crack. You are more likely to slice through the compacted layer, rather than shatter it, which can result in smearing under the foot.”

Growers facing this situation would be better running the tine just above the damp, compacted area, he noted. If compacted layers were shallower, perhaps at plough depth, growers could work the ground in the spring as the soil was likely to be drier.

Growers needed to assess each field individually, he said. “You need to look at the depth of problems, look at the scenarios, and work out when it is best to tackle it.”

Where several fields required attention, growers would be better off picking the worst affected areas and dealing with them first, then tackling others the following year, he added.

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