Size for size, crushed granite and silica are interchangeable, but neither is a suitable alternate to Turface.

Al

Thanks Al. No I would not try to substitute silica sand for Turface, just wondered whether the granite and silica sand were interchangable.

From what I can tell (not a scientific test for sure) but silica sand doesn't seem to absorb much, if any, water, and silica appears to be roughly the same size as the crushed granite I've been buying. So that's why I was wondering if silica and granite were interchangable inthe gritty soil mix.

If they are interchangable, this might help some list members who are having problems locating crushed granite in their area.

Thanks Al. As always, your advice is greatly appreciated!

Dave

The purpose of the granite or silica is to reduce or balance water retention while still adding o/a volume. They are particularly valuable because they both come pre-screened and the size is on target. Anything nonabsorbent would work if the size was the same & the material was durable/nonphytotoxic. Crushed glass, plastic beads, ...... would all work if the size was appropriate.

Because the silica sand is usually smoother than the highly irregular crushed granite, it has less surface area, so it actually holds a little less water (on its surface - not internally, like Turface) than crushed granite.

Al

Bookmark this reference on mesh sizes. The formatting is horrible but I hope you can follow it.

Your mesh #20 silica sand is too small. This would be an average particle size for the sand of 0.841 mm. Tapla's guideline for the rock component of the mix is:

• chick grit #1: 1/16 - 3/32 inch (1.6 - 2.4mm) you can sub #1 cherrystone/quartzite if available
• poultry grit #2: 3/32 - 3/16 inch (2.4 - 4.8mm) you can sub #2 cherrystone/quartzite if available

In the other thread where you found me, I was looking at a carefully screened silica sand that had sizing between 2.0 and 2.5 mm. That falls within Tapla's guideline.

The key idea you need to think about with rock is water adhesion to surfaces. A crushed granite like poultry grit has many irregular surfaces and more surface area. Therefore, more water can adhere to its surface. Silica sand is more rounded and has less surface area. That said, I wonder if that really matters. In a soil mix that includes turface and bark, is the contribution of extra water cohesion from crushed granite really going to move the bar on porosity and water holding capacity by more than a few percent?

Oops, this thread is 11 years old. Sorry about that :)

westes: You just helped someone from the Midwest who’s haunting these old threads. Never too late to help!🙂