Not all plants use mycorrhizae. Just throw a handful of compost in the soil mix and your all set.

While I realize you feel this is a must-learn topic the multiple threads are getting a bit spammy. Maybe they could be combined into 1 thread.

I did combine them in one thread but this is actually in my opinion an entirely different post.  Almost all fig growers will want to know about fertilizer, this post is how to get the most out of your fertilizing efforts.  It is not where I feel this is a must learn topic, it simply is a must learn topic since 95% of all plants need a correct bacteria to fungi ratio.  Hopefully these posts will help someone who is simply wasting money on chemicals.  Thanks for your concern, I will try to let that be all the posts I make on this wide subject but no promises.

Drew51 only 5% of plants do not use the mycorrhizae however some of those plants are debatable.  I agree thow, through compost on top that is essentially what I want people to do, compost will usually be inoculated with mycorrhizae especially forest materials like leaves and wood chips.

This is an interesting thread. Tennesseefig So true, especially figs can thrive in low fertile soil. I always use a combination of organic and synthetic fertilizers for all my plants. The microbes or the beneficial bacteria trade nutrients for sugar with plants and adding tons of NPK wont work if there is no life in the soil. However in a more challenging environment like our climate we do need to make sure the plants are fed properly especially for figs and citrus. So in spring and autumn I add a layer of composted, milled and oven heated (at over 200°C ) organic fertilizer, plus some mycorrhiza fungi deep into the soil where the roots are exposed. I think my plants are benefiting from this and this is what I love about being an amateur gardener when it comes to figs and citrus. Learning something everyday. It would be interesting to know what other folks are doing. 

Tennesseefig,
I enjoy all your posts and appreciate you're trying to make info available.
I'm about to try biochar on a number of my plants and am excited as I grow in pots (over 400) and leeching of micronutrients is always an issue.
In an attempt to protect myself from nematodes I will be careful about what compost I use. I am going to inoculate my charcoal with worm castings. Normally I use a lot of bunny poo but I moved and my bp supply has been severed.

I emailed Rootgrow here in the UK asking for clarification about some of the arguments mentioned here and elsewhere. When I get a reply I'll post it.

Hey that's awesome Michael!  400 plants in pots??? WOW!  Do you have any plants in the ground at present time?  I haven't used the biochar yet but it's coming soon I hope.  I use whatever I can get lol, cardboard, leaves, wood chips, horse, cow and chicken manure etc.  Keep us posted on the biochar experiment.

Vinny, that sounds awesome.  I definitely feed the soil and recommend everyone do the same.  I personally brew compost teas, use fish emulsion and loads of mulch, any and all that I can find as long as it will break down that is.  I have access to tons of sawdust but there is a lot of cedar in it and cedar takes forever to break down so I haven't used it.  You can harvest your own mycorrhizae from your own land, not sure if you have tried that.  Basically it involves burying a sock or panty hose with white rice inside near a large well establish tree for a month, then collecting the sock and emptying the rice and microbes into a solution of molasses and water and allowing this to ferment for another month.    Then you could use that, I haven't done this in this way.  Instead I try to create an environment with mulch and then feed the microbes in the soil, nothing fancy.   

I use Rootgrow when I plant anything, indoors our in my greenhouse/garden.

I add grass clippings , pumpkins from my garden and chicken poop. I also cover crop with rye, clover and mung beans. Makes a difference for sure. 

Grant, do you cover crop your entire orchard space with rye or just around each tree?  I would be interested to know more about your cover crop strategies.  How long have you been using clover?

I cover around each tree.I have 20 acres and a lot of in ground trees so I cover for weed suppression . I use crimson clover and beans to fix nitrogen.The summer heat will kill the annual rye but the clover will live.I am thinking about using turbo radishes around trees this fall to loosen the clay soil,they will grow deep and die with winter freeze leaving holes in the ground when the radish decomposes.I also want to experiment with planting winter rye around the trees late summer to pull nitrogen out of the soil and tie it up to help tree harden off for winter,looking for the winning combination.I am a big fan of no till gardens and companion planting.

 How often do you have to reseed the crimson clover and when do you sow it?  Do you just broadcast or what?

this is good info
i have watched literally over 100 hours of Elain Inghams videos, and many others on soil science.
a couple of things that were not mentioned...
Compost... yeah, good stuff, but its only as good as how its made
and the ingredients going into it..

another thing is that he didnt really mention how to get the fungal count up.
wood chips, or other woody material (like sawdust) is great after it breaks down.
wood chips used as mulch slowly break down and increase the fungal count in the soil.
You can add nitrogen to wood chips (or sawdust ) to get them to break down faster.
i use urine.

I had read a white paper on figs and mycorrhizae, and it said that yes, fig trees do benefit,
but they are not as dependant, or have as high a relationship with those fungi
as some other species.

one way of getting mycorrhizae is to find a really old tree, in an area that hasnt had a lot of humans clear cutting in a long time (forest, park etc..)
and get a couple of shovel full of soil from under a large tree.

AMF fungi can also "share" minerals and water between plants.
if 2 plants are connected to a fungal network, and 1 has plenty of water, but lacks phosphorus
and the other has lots of phosphorus, but is in need of water, the fungi will transfer the nutrients as needed.
an "internet highway" if you will...
i grow sunflower near most of my fruit trees just for that fact.
Sunflowers are a AMF fungal host plant.

here are a few snippets from my files that might be useful...

=============================================

Plant species differ in the extent and dependence on colonization by certain AM fungi and some plants may be facultative mycotrophs while others may be obligate mycotrophs. Host plant species differ in the degree to which they depend on the symbiosis. That is, some (mostly weedy) species benefit little, even though they are capable of becoming mycorrhizal. Other species are mycotrophic: they depend upon the symbiosis and make little growth without it unless heavily fertilized. Perennial grasses are often strongly mycotrophic.

Maize is an obligate mycotroph, which means it is heavily dependent upon the symbiosis with
AM and makes little growth without it unless heavily fertilized. Maize is also a trap plant with
ability to attract mycorrhizal propagules even when present in low amounts, a likely event in the
tropical soils. A 90 day fallow in corn can reduce AM active hyphae by 57%.

There is a lower incidence of mycorrhizal colonization in very arid or nutrient rich soils. When the level of soil fertility and humidity are increased, the dependence on the mycorrhizal condition decreases to a point where the plant becomes immune to colonization. The addition of fertilizers containing easily soluble phosphorus, including non-composted manure, will greatly reduce VAM colonization. An important consideration in AM fungus production is the level of available Phosphorus in the media in which the plant hosts are grown. Plants growing in high P situations limit colonization of their roots by AM fungi.

It has been well established that the AMF activity is decreased by non-AMF host plants and highly mycorrhizal host crops increase AMF inoculum potential of the soil and colonization of the subsequent crops (Black and Tinker, 1979; Gavito and Miller, 1998; Karasawa et al., 2002). For example, Karasawa et al. (2002) found an increase in AMF colonization and growth in maize following sunflower (Helianthus annuus, mycorrhizal) when compared to corn following mustard (non-mycorrhizal).

Many common weed species of Manitoba are AMF hosts. This includes Green foxtail (Setaria viridis), Wild oats (Avena fatua), Canada Thistle (Cirsium arvense), Chickweed (Stellaria media), Cleavers (Galium aparine), Dandelion (Taraxacum officinale). Weeds in the families Chenopodiaceae,  Amaranthaceae, Polygonaceae and Brassicaceae are non-mycorrhizal. This includes Wild buckwheat (Polygonum convolvulus), Lambs-quarters (Chenopodium album), Stinkweed (Thlaspi arvense), Redroot pigweed (Amaranthus retroflexus), Kochia (Kochia scoparia), Canola (Brassica napus).

. In a pot study by Kabir et al. (1999), a 90 day fallow was found to decrease active hyphae by 57%,  AMF colonization of maize was decreased 33 % and the uptake of phosphorus by 19%, zinc by 54% and copper by 61% respectively. Clearly, fallowing is a practice that is detrimental to the AMF-plant symbiosis.

Grant are you using Apple or Windows?

Maybe this would help?