22 June 2001

ITCF urges subsoiler caution

FRENCH growers at last weeks Les Culturales show are itching to get out with subsoilers this summer to try to rectify damage done by a winter almost as wet as in the UK.

But ITCF soil and tillage expert Gilles Eschenbrenner warns time and money will be wasted unless structure and soil condition is checked first and the following crop considered.

"For example, if there is a wheat crop following there is less need to subsoil," he says. The effort would be better directed at land destined for more compaction-sensitive crops.

Checking soil moisture at the depth of cultivator operation is also vital. If the soil moulds into a ball it is too wet, he says.

Setting operating depth correctly, and checking the machine operates at that depth is critical. Soil cracking spreads up from the foot of a subsoiler in a V-shape so depth must be well below the minimum shattering depth required, he says.

For example, in a demonstration at Les Culturales, the Rau Delta Plow operated at 35cm (14in) deep, fractured soil effectively only to 25cm (10in).

Subsoilers with wings spread shattering width, so legs may be further apart, or depth reduced with such tools, adds Mr Eschenbrenner. However, if conditions are wet the risk of creating a pan is greater, he warns.

Old designs of subsoiler with curved legs should be avoided. "They lift the soil in big blocks which take many passes to break down, and they turn the blocks over so fertility is lost."

But whatever tool is used, checking the need for it and the moisture content of the soil first should be priorities, he concludes.