At a recent Teagasc tillage farm walk, analysts looked at different soil structures. They compared three different cultivation methods on soil structure:
- Direct drill with organic manures; - Plough and no organic manures; - Plough and organic manures.
I was extremely interested as we have changed from ploughing with organic manures to direct drill with organic manures and rotation.
All three had good soil structure when you examined the field but, where they had traffic and heavy machinery, they had some compaction under the surface, some deeper than others.
What I did learn was the damage that is happening below the surface isn't visible until you dig a hole and look.
What I didn't understand was how much was to do with the cultivation method.
In other words, we all understood that the heavy traffic was doing damage and that the organic manures really can help the soil structure.
What I didn't see was the difference the cultivation method was making.
I know that most farmers that have changed to direct drill are very happy with their decision.
Usually the decision to change is made for a variety of reasons, but I don't think that soil structure is the main one.
When we got home, we went out and dug holes in our fields and found something similar.
Where there was traffic, especially at the headlands, there was much more compaction. The soil structure was much better further out in the field.
We had to plough half of one field in the spring, after the winter oil seed rape failed. Because we felt that compaction could have been part of the problem, we ploughed it in the spring and put in spring oil seed rape.
When we look at this field that had half ploughed and half direct drill, I can't see any difference in soil structure.
To be honest I don't think the cultivation type has much to do with soil structure.
I think the organic manures and heavy machinery have far more damaging effect.
So, how do we solve the areas that are damaged?
Teagasc are very adamant that the sub-soiler is not always the right answer.
In a very dry year like we have just had, nature has done a lot of sub soiling for us, with deep cracks in the soil.
If we do decide to go out with the sub-soiler we need conditions to be very dry or you could end up doing more harm than good.
My own conclusion is that more organic manures, more cover crops with rotation and less heavy traffic is how we will overcome our normal compaction problems.
Anywhere that is more serious like the tram lines and gateways we will give them a run of the sub-soiler.
Meanwhile, we have a busy few weeks ahead of us trying to get all the winter crops in. Then hopefully we will get them rolled and all the stones picked. Anyone who knows me knows that's one job I'm not looking forward to. I can be extra grumpy those days.
Philip and Helen Harris are tillage farmers in Co. Kildare. Follow P&H Harris on Twitter @kildarefarmer