Compacted mineral soil problem

[nut]

I just noticed a prized plant that I tried to degraft has succumbed to rot,the whole plants fucked!!then what got me concerned next was when I was dumping the soil in the bin along with the plant I noticed the soil mix I had made has become very hard..I had to dig it out with my finger to clear the pot,it clearly drains well as it was bottom watered 4 days ago and was basically dry.now my stress is I've just potted pretty much all my favourite Mexicans in this mix.its made of a sifted commercial cacti mix,river sand,granite dust,which I also sift to leave me with mostly larger particles,about a quarter spongelite and some crushed limestone.i don't think I lost my plant to rot because of this mix,it had not even rooted yet but am worried for my others.should I repot and formulate a less compacting mix???

[gtarman]

Do you have any pics of the mix after the plant carked it? It could have been a case of too many fine particles, which can be a problem with sand and granite dust etc, but if you say you sieved them properly it would be hard to say...

If we're talking cacti I'd say maybe it's just because you watered it before it had any roots?

Edited December 20, 2013 by gtarman

[nut]

I bottom watered but not enough to actually allow any direct contact with the plant,was hoping a bit of evaporative moisture mite have encouraged some root development,the plant itself never touched water.it was sitting on a dry layer of spongelite on top of the mix proper,I've degrafted before and done the same without probs.im just not sure what constitutes too greater soil compaction is all.as I said it drains well.i had let this degraft callous for weeks.

[Sallubrious]

I'm no chemist but it sounds to me like you could have inadvertently created the conditions for a reaction in some ways similar but on a lesser scale to what you'd see when concrete cures in a process known as hydration.

Your granite dust is high in silica and other minerals so when you add limestone and water it could be reacting to form weak/limited chemical bonds and resulting in the formation of partially complete/ noncontiguous geoploymer.

Teo or Alice would be able to say if I'm talking shit though so wait for their opinion.

I've done a similar thing with some of my first mixes I made up for Trichs when I used to add gypsum, dolomite and basalt rock dust to cactus potting mix. The plants never thrived but they are alive and relatively healthy.

Edited December 20, 2013 by Sally

[Sallubrious]

After I wrote that last post I started to think that I could have contradicted myself with the first and second statements I made.

After 2 bottles of red wine I'm still undecided if it was an either or type of situation. After sitting here with a box of matches and a handful of coins to assemble visual representations of various molecules and crystalline structures, I'm starting to lean towards the geopolymer theory.

This is a really intriguing field & I'm even starting to consider the possibility that the pyramids could have been constructed from a man made geopolymer.

[zelly]

I just noticed a prized plant that I tried to degraft has succumbed to rot

It sounds like the rot had already set in prior to you even degrafting.

Not much you can do there, besides acknowledging all grafts will eventually fail.

If the rot set in after you degrafted the head, the mistake was watering a plant that had no roots.

for lophs, you should move to an all mineral based soil & ditch the commercial cactus mix

[nut]

Yep the rot was well advanced.i actually can't stand MOST grafts,they are a means to an end in someways but i don't like the form they tend to take.really I don't think the soil density is too bad I can crumble it easily in hand...and as for the commercial mix that's about 15 - 20 percent of total.i think that's good advice zelly.much of the soil I saw in south Texas last year had a similar density to what I've happening now.ive never had rot problem with plants grown hard on own roots but have had drama with a few grafts.i degrafted it as it was starting to get that Incredible Hulk on roids look,pups sprouting everywhere etc...thanks for the advice people :-)