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.