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Why is water retention bad?

6 months ago

I’ve done my research and reading on the water movement and retention threads as well as many others going back as far as Houzz presents, and I think I have a handle on most of the principles presented, with one remaining point of confusion.

If your particle size is sufficient to eliminate a perched water table and ensure root aeration, why then wouldn’t you want to use the substrate with the maximum water retention?

Part of my confusion seems to be that water retention as a term seems to encompass both water held between particles (macro pores/perched water/undesirable) but also water held within or on particles (micro pores) and I think most of what I’ve read about problems with water retention was referring to the former. So I’m not sure of the negatives to retaining as much water in micro pores as possible.

As a thought experiment (to check my understanding) I was considering the components of gritty mix and what would happen if your media was comprised of 100% of each component. 100% grit would be undesirable for low water retention and 100% bark would be undesirable for decomposition and lack of aeration (due to stratification/lamination of the bark particles.) But why would a 100% Turface growing media, if it was screened to eliminate the PWT, be undesirable?


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