Growers are being urged to investigate the location and extent of their soil compaction before carrying out potentially wasteful and costly remedial work.

Last season has taken its toll on soils, as heavy machinery worked in wet conditions to establish crops or waterlogging led to slumped, anaerobic conditions.

However, independent soil consultant Phillip Wright says that compaction is generally not as deep as many would imagine.

“It is very important that growers understand where the problem is and don’t just assume it’s bad because of the year we’ve had.

“Sub-soiling at the same depth as it’s always been done – or a little deeper on the assumption it’s worse this year – could actually do more harm than good,” explained Mr Wright on the Tillage-Live Knowledge Trail.

Sub-soilers should be working just below the compacted layer to provide the most shatter, with any more depth likely to compact softer soil against the hard layer above.

If more lift is required to increase loosening, sub-soiler wings should be lengthened or the incline increased, depending on conditions.

“An increase in incline can cause more compacted soil, so in conditions where there is a little more moisture at depth, lengthening the wing would be advisable,” said Mr Wright.

He also advised that where headlands had become particularly compacted, it would be better to run through at a depth suitable for the majority of the field and carry out a second, deeper pass on headlands to avoid bringing up large lumps on the first pass.

Also, where waterlogged soils have slumped and become anaerobic, Mr Wright urged that the best remedial treatment would be to establish a good crop to breathe some life back into them.

“Fallowing would not be a good idea, as a root system is the best tool to open the soil up, get some air in there and removing excess water,” he added.

Variable cultivations

Getting your implement depth right this year when correcting compaction could be assisted by variable-depth cultivations offered by Frontier’s precision farming division SOYL.

Also on the Tillage-Live Knowledge Trail, SOYL agricultural development manager David Whittoff said the service could be offered on two levels.

Using soil conductivity surveys to establish soil zones based on texture, growers can then dig pits in those soil zones to find out where the compaction is and produce a cultivation map.

An automatic GPS depth controller retro-fitted to the implement then varies the working depth based on the information provided by the maps.

“It costs the same as a seeding plan at about 50p/ha, but requires a degree of interpretation of conditions from the grower,” said Mr Whittoff.

A slightly more expensive option uses a hydraulic penetrometer on a GPS-equipped ATV to produce a compaction map across a field.

The service costs abound £15/ha and is predominantly aimed at higher-value crops such as potatoes where compaction and cultivations can have a bigger effect on yields.

“There are fuel and wear savings to be made and Cranfield University is carrying out extensive trial work looking at the agronomic benefits of the system,” added Mr Whittoff.

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