Farm Ireland

Tuesday 26 September 2017

Testing season but min-till can still provide maximum reward

Compaction, slaking and water logging combine to cut harvest yields

Improved soil structure often helps aeration and the water-holding capacity of the soil, which makes cultivation easier and allows better utilisation of water
Improved soil structure often helps aeration and the water-holding capacity of the soil, which makes cultivation easier and allows better utilisation of water

Ciaran Hickey

IT WAS a testing season for the minimum tillage trial carried out by Teagasc Oak Park at the Knockbeg site. In fact, it is the first year in 10 years that there is a noticeable difference between the min till and the plough-based system.

The winter wheat crop was sown in mid-October and conditions at sowing were very good but then the weather broke and it rained continuously for almost a month.

This leaves the question of what caused the gap between the two systems and how best to avoid this happening in the future.

The soil at the Knockbeg site has been cultivated at 75-100mm depth (three to four inches) since the start of the trial.

Because you normally work in the upper part of the soil with min till, organic residual matter can partly remain on the soil surface, reducing the danger of soil capping and erosion.

The absence of regular and intensive loosening results in better soil structure and stability and the improved ability to carry traffic.

The improved soil structure often improves aeration and water holding, makes cultivation easier and allows better utilisation of water.

It also has a great impact on the water infiltration rate.

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In well-structured soils, the permeability is fast enough to prevent excessive water build up.

During the wet harvest of 2008, this was very evident from talking to min till practicioners who were able to travel their min till ground better.

The idea is to leave a good soil structure from one year to the next and that the cultivation is only a requirement to create a stale seedbed, free of trash and weeds suitable for drilling.

However, based on the events of last year, the question is do you need to cultivate for the plants’ requirements also?

My gut feeling at the moment is yes.

The problem is that the weather conditions of the last few autumns meant that min till land was cultivated in less than ideal conditions and problems not normally associated with this form of tillage cultivation were found.

The structure that had been built up was under threat by the forces such as compaction, slaking and water logging.

How these factors affect production requires a clear understanding of what is happening below the ground, where we normally concentrate on what happens with the crop at the surface.

In order to assess this we must address a number of very pertinent issues.

We need to know what the aim is: An ideal seedbed.

How do we achieve an ideal seedbed: Compaction versus consolidation.

What are the possible problems: Compaction, slaking or water logging.

How to examine soils for problems: Field inspections.

What is a good soil structure and how does it develop: What are the factors affecting soil structure?

And last but not least we need to know: How to tackle compaction.