Monday, 9 May 2011

Strip tillage - a new, moisture-saving approach to cultivation

I was fascinated to read a couple of articles in last week’s Farmers’ Weekly on strip tillage, something with which we’re not that familiar in the UK.  Strip tillage is a method of cultivation and direct drilling whereby strips (several inches wide) are tilled leaving undisturbed land in between (so typically no more than 30% of the field surface is cultivated).  Bands of seeds are then drilled into them at wider row spaces than conventional drilling.  So both the row of seeds, and the undisturbed space between, are wider and further apart than in conventional systems. 

The first Farmers’ Weekly article (not available online) highlighted the time and cost savings in establishment using just one pass of the tractor – the farmer featured, Mr Lole, reckoned he saved between £100 and £150/ha by not ploughing, power-harrowing or culti-pressing.  The drill used has been used to drill wheat, OSR, beans, maize and linseed and costs around £25 an acre to run.  Mr Lole reckons that a concurrent £25/acre saving in fertiliser could be made by using strip tillage, neutralising the cost of drilling.

The second article, available here, features Norfolk farmer Stephen Temple who has used strip tillage for the first time this year to grow maize.  Dr Temple reckons that fuel and time savings have been substantial.  In addition, he believes that wind erosion on some soils will be reduced, and the over-wintered stubble will be an asset for wildlife.  He also suggests that inverting and then moving all of the soil in a traditional cultivation sequence causes moisture loss that could delay germination.  But with the strip tillage system only narrow bands of soil are moved, and exposure to drying lasts just a second or two before the drill's press wheels seal the surface again.

"Average annual rainfall on this farm is about 600mm, but this year the spring has been exceptionally dry so far and we had only 15mm between late February and mid-April," he says. "It is a situation where conserving soil moisture is likely to be important, and I think this could an important factor for farmers in low rainfall areas."

Unfortunately, there’s little on the web about strip tillage in the UK – a Google search will throw up one or two Farmers’ Guardian and Farmers’ Weekly articles, but little else about the deployment and use of this technique in the UK, although, as I mentioned in an earlier post, the Centre of Excellence for UK Farming is undertaking some research into the system.

It does seem to be popular in the US, and a number of other countries, however.  The technique was apparently ‘invented’ during the 1980s and US strip tillage seems to differ to the one-pass system described above, in that it is undertaken in the autumn to provide improved drainage and better soil warmth for spring planting.  In addition, fertiliser is often injected into the strips rather than just being spread on top, which reduces wastage and improves utilisation. 

There’s a wealth of information on the web about US strip tillage but there appears to be several different ‘types’ – I came across references to ‘north’ and ‘south’ strip tillage systems as well as systems whereby the earth within the ‘strip’ is not only cultivated but also banked up to 3 or 4 inches tall.  I found a couple of interesting articles from across the pond on it – here and here.