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Aspects of Thatch

Wednesday 21, Oct 2020

 

There is a huge amount of research and literature on thatch.  Phil Ford (Thatch, University of Ballarat 2011) focuses on just two aspects of thatch, the effects on root growth and perched water tables.

 

This is a great reminder on the effects your maintenance practises have on thatch and what happens below the surface.  For a sand-based sports surface, you can extend the viable life of the surface, providing you take a two-pronged approach.  In construction, choose a rootzone with moisture retention 15-25%, like the USGA says, and then dust religiously, as soon as the turf is mature enough to take the traffic.

 

Normal Thatch

‘Normal’ thatch has a Moisture Retention (MR) of around 30% (quoted on a volumetric basis, at Field Capacity, as are all the other MR figures in this paper).  The underlying soil might have an MR of, say, 25% (if it’s a loamy soil).  When the new roots arise each year from the crown or the nodes, and start to move down the profile, they are being asked to move from a thatch zone of 30% moisture, into a soil zone of 25% moisture.  The roots that try to do that will get less auxin and will stall.  The roots that travel sideways and simply hang around in the thatch layer will be the ones coming up with more water, and so they will get more auxin.  The result is a lack of root depth.  But it gets worse.

 

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