21 April, 2017
Hidden losses associated with compaction
Do we recognise the physical impact that livestock are having on our soils? The impact may be subtle but the message was hit home recently while talking to a group of Northern Irish farmers on this particular subject. Usually, the evidence is anecdotal but on this excellent farm there was proof of the effects that surface compaction can have on soils and grass yields.
Last autumn a paddock was identified as having shallow compaction and half of it was shallow aerated using a slit aerator. A soil pit was dug in both halves of the paddock and the top 10cm of sod was removed to compare. The differences were immediately visible.
The aerated sod was drier, had a greater number of worms present, the grass roots were whiter and deeper and the physical structure of the sod was looser.
The non-aerated sod was visibly wetter, had very few worms present, the grass roots were more shallow and the physical structure was tighter.
The farmer's CAFRE advisor had measured the grass on both halves of this paddock separately beforehand and there was 18% more grass on the aerated half of the paddock. It is likely that this difference will be maintained for each grazing this season. This 18% increase was achieved with the same amount of nutrients as the area that was not aerated. By identifying and rectifying shallow compaction we are maximising grass yields and improving fertilizer use efficiency which is good for the farmer and the environment.
