I would like to hear a discussion by our resident fugusologists/bacteriosophers on my pet peeve: the inorganic freaks that grow trees in rocks because, they say, it avoids root rot caused/encouraged by potting mixes that consist of mostly "fines". Supposedly, too little air space and/or retaining too much water/moisture is the culprit. I use equal parts top soil/pine bark soil conditioner which is very dense and retains moisture to a fault. I add all the trace elements and ~10 to 15% bonechar.
They conflate what is necessary for pines with what is good for everything and I disagree. I think the necessity for skree is limited to pines, and all others do just fine in damp soils. Although I do like to cycle wet, dry, wet, dry, it's not practical to check a hundred pots of every size and description when watering everyday. At watering time I turn on the hose and soak everything in sight and it still takes 15 minutes. I have personally killed many more trees by letting them get too dry than by letting them stay too wet.
I believe that a healthy family of mircrobes in the pot are much more important to the health of the tree than anything else, and that that population is MUCH smaller and less diverse in a pot full of rocks with token amounts of organic materials and few sources of trace elements. I view trees in rocks as in marginal health that is like a person on an IV. They're OK just as long as the attendant is attentive with feeding and watering, but that is not nearly as healthy of a situation as a tree growing in a medium that has an on-going food production chain of healthy microbes that have a full diet, not just infusions of NPK. That same infusion of NPK into my mix goes much further, so I feed once or twice a summer and the plants have a consistent supply of nutrients rather than peaks and valleys.
Trees in rocks are not as robust as trees in good soil. They are therefore more susceptible to having unhealthy root systems and without a diverse population of microbes cleansing the soil the environment can build up unhealthy levels of materials that would have been recycled by a more diverse microbe population. If growing in inorganic high-draining rocks was the solution to root rot, it would never occur in "high draining inorganic mixes". It does occur, as attested to many, many times, right here.
Just how important is a diverse microbe population in tree and/or soil health? And, can a mix with 95% rocks ever be "balanced" with adequate trace elements and a large, diverse, consistent, population of microbes?
. I have just seen too many nursery plants and some of my first bonsai experiments that had basically dead soil. This was completely due to my ignorance and I have been remedying it with organics and fungal transplants but for those out there that don't know anything about soil health or are heavy chemical users (unfortunately there are many in my local club) leaning on fungal and bacterial health in the soil isn't going to work.
