21 July 1995

Now time to check compaction levels

ITSTILL isnt too late to test-dig fields now to check for compaction, says ADAS soil scientist Selwyn Richardson. Indentifying compacted layers now means cultivation strategies can be planned, so avoiding unnecessary work at a busy time.

It is a message that has been well learnt at Bedfordia Farms, host to this autumns Cultivations 95 Event*. The farm has used ADAS for six years to produce an early summer report on soil condition on its predominantly chalky boulder clay farms.

Seeing benefits

"I think we are starting to see the benefits now," says Bedfordias arable manager, Bob Green. "We are certainly not pan busting where it will be a waste of time. We want to protect ourselves from recreational cultivations."

Mr Richardson agrees. "There are more important things to be doing after harvest. Drilling winter wheat by Oct 15 is the objective on this soil. Any delay cuts yield, so you dont want to be running about with unnecessary operations." There is a cost, too, he stresses. Flat lifting wastes £30/ha (£12/acre) when not needed.

His advice is to dig three representative pits in each field, going down to 40cm (15-16in).

Tough, compacted soil at 20-24cm (8-9in) means ploughing is vital. If it appears at more than 24cm, sub-soiling is necessary.

Provided roots are still growing they can be a further indicator of compaction. Any restriction to their development is a sure sign of solidified layers.

If compaction is found there is no alternative to taking it out, stresses Mr Richardson. "Deep drought cracking on clay soils can help alleviate the problem," says David Parrish of Huntingdon ADAS. But Mr Richardson urges growers to remove any impediment to rooting.

"Under severe drought stress or waterlogging that can cut yield by several hundredweight an acre. That will pay for a lot of sub-soiling."

*Cultivations 95 is on Tue, Sept 12, at Knotting Green Farm, Knotting Green, Beds. A large area of cereal stubble will ensure ample opportunity to see leading tillage equipment in action on heavy land.

Digging for a compaction picture… Selwyn Richardson (left) and David Parrish of ADAS Huntingdon, check soil structure.