K-Feldspar

Calcium, iron, magnesium, potassium ,,, alumina, sodium.
Came from the Red Rocks area, base of the Rockies.

I received around 3 or 4 tons of it yesterday.
I thought they were bringing 3/4 rock. This is like decomposed granite. No complaints. It's beautiful stuff.

Question is if it's a worthwhile soil amendment or not. How alkaline is it? I'm not familiar with it and was hoping somebody here was.

I would suggest getting it tested. An M3 test like the logan labs standard soil test and then a heavy metals test would be good. Or if you can find a company that's pulling from the same area and has already done that testing it would be even better. Certain things like Cadmium could be problematic for your health when growing edible crops.

It came from a residential area. While I can't find a soils report, I did find some water quality reports. While radon and uranium were detected, they were within limits. The only violations had to do with chlorine by products. There was also a lot of mining exploration in the area, which turned up traces of heavy metals. The only real value was in the aggregate. Red Rocks is at the base of Pikes Peak of which there is a fair deal of information on Pikes Peak granite.
This is basically red pea gravel with a lot of sand and flour. The information I turned up and the color of the aggregate tells me this is KAlSi3O8.
Feldspar is either KAlSi3O8 or NaSi3O8 or CaAl2Si2O8. Alumina silicate with some attachments.

Think if I use it, I will get it tested, see if I have more than just some pretty dirt. I haven't tested the Ph. I imagine that it's a bit high.

I would investigate the breakdown time--the length of time (days vs years) it takes for the potassium and other goodies to become "plant available".

We have loads of feldspar here in the mid-west. It takes a very long time for the K to become available. We literally have tons per acre naturally and still come up short on K in soil tests. If that is any indication...

growingcrazy said:

We have loads of feldspar here in the mid-west. It takes a very long time for the K to become available. We literally have tons per acre naturally and still come up short on K in soil tests. If that is any indication...

Click to expand...

Seems it's locked up pretty good. It would take a low pH and if you have any calcium in your soil...

Just as well. It's good for worm grit and clay. The color makes everything a bit more interesting.

Cadmium
https://pubs.usgs.gov/of/2014/1082/pdf/ofr2014-1082.pdf

h.h. said:

Cadmium
https://pubs.usgs.gov/of/2014/1082/pdf/ofr2014-1082.pdf

Click to expand...

Cadmium would be a definite red flag. Glad to see you're looking into it.