I am evaluating the use of subsoiler in a 50ha plot, which has been cropped within a no till system for the past 18 years. Some experts believe that the resulting increased soil porosity is favorable, but others say it goes against the no till system and advise rotating more instead.

 

Based on my experience and observations of neighboring fields, shallow cultivation is not compatible with direct seeding, unless there are specific compaction problems diagnosed. It is like a painkiller that relieves pain, but does not cure the disease.

Soil doesn’t become compacted with the right crop rotation, except in wheelings from bulk trucks and harvesters. Cultivating soil to break up the soil profile may at first accelerate water uptake and aid aeration, but it can also accelerate their recurrence.

To reduce compaction, we must resort to the use of crops that improve the porosity and stability of soil by the action of their roots. Rotations with corn, sorghum, wheat etc produces a more stable porosity than that by machinery.

Cultivating increases costs and does not provide a long-term solution. In the last cycle, we decided to tackle areas of headlands with serious compaction. Working at a depth of 18-20cm, it cost $65/ha. However, the following year there was the same compaction.

Sometimes the compaction level is very high because of the soil properties. In these extreme cases, and where there is no alternative, you should try breaking it up while not disturbing too much topsoil, working deep rather than on the surface. For these tasks, we must use appropriate subsoilers working at a depth of 25 to 60cm with legs arranged at a variable distance of 0.7-1m so that is why I am evaluating its use this season.

Federico Rolle farms 2,250ha of rented arable land in the Pampa area of Argentina. He grows soya beans, sorghum, maize and wheat using no-till techniques and GM crops. He has a part-time role helping Brown & Co in the region.

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