rice hulls vs. vermiculite vs. pumice vs. perlite

[MrTwister]

Can anybody please shed a bit of light on this situation? I'm mixing my own soil and I'm using coco coir, peat, earthworm castings, and compost; however, I'm also using some other light/drainage type stuff.

I realize that each of these amendments (listed in the post title) are different and not entirely intergangeable, but I started out wanting equal parts of all of them. On the other hand, it is only for lack of understanding the differences between them. The two major factors I found between them are price and availability. For one, I can get 10 yards of heat treated rice hulls for $390 and carry it on a flatbed myself (compacted). Pumice is like $15-20 per yard and it's an 8 hour truck haul from me, so I have to figure the shipping logistics. Hopefully it's not much more than say $500 for a 12-20 yard truck. Even at $1000 I think that wouldn't hurt my feelings too badly. Working on that price currently.

Vermiculite and perlite are very expensive in comparison. Vermiculite holds more moisture which is not a huge concern for me... that I know of. Vermiculite also releases beneficial minerals. Good thing I'm sure. I can't find any other reason to want to use vermiculite. Also how much vermiculite? I'm just not so sure- I can't even find a source running larger than 1 cu.ft. bags.

Perlite is cheap enough, but not nearly as cheap as rice hulls and I read a link on this forum that lead to a Perdue university side by side on vermiculite vs. rice hulls. They seem to be essentially interchangeable.

Any words of wisdom would be greatly appreciated. I feel like these ratios are somewhat arbitrary and I would like to drop some science on them.

 

[Seamaiden]

I hate on vermiculite, I seriously detest that stuff. Dusty, holds water, pain in the ass to work with. I moved away from perlite because it, like vermiculite, is a mined product and is therefore unsustainable. I use rice hulls in my coco coir (nothing else really added, maybe a bit of worm castings, otherwise I keep the mix pretty simple then feed as they need). I do not use them in my soil mix because it's in a great big planter and damn if I'm gonna try and mix rice hulls into it, plus, it doesn't need the drainage, just re-amending annually.

I know others who have gone with rice hulls for their large OD grows (raised beds or extremely large SmartPots) and they seem to like that it doesn't float to the top like perlite. It also offers potassium silicate, if I recall. Overall, I believe I purchased my last bags of perlite last year, and won't be going back unless I make another attempt at perlite hempy growing.

Some links, perhaps they will help, perhaps you've seen them already, but this is a discussion I like because I would love it if we cannabis growers moved AWAY from non-sustainable farming methods.

Organic and compost-based growing media....

http://www.cabdirect.org/abstracts/20083101543.html

You may have to sign into Google to view this paper on Carbonized Rice Hulls.