I live in the Foothills of the Sierras in Northern California. I dont remember what climate zone I live in but if it can be looked up by zip code I am 95922. I am at approx elevation of 2000-2500 ft.
I purchased a labeled "miniature" (not dwarf) bare root nectarine tree that I have dug a hole for a about 4 ft. Wide and about 5-6 ft depth. I DEFINITELY need to amend the native soil. It is very Orange and clay like. (I have a large vegetable garden.) What minerals should I add to the native soil and how much of each? How much compost and sand should I add also?

Whether or not to amend a planting hole depends upon the mature size of your tree. If its canopy will be less than 4 feet wide at maturity, then your hole is big enough and you should amend away. If the tree is going to be bigger than that, don't amend or dig a bigger hole. Essentially, when you amend for a plant, you are creating a more pleasant space for them then the bigger world is going to provide. Plants don't want to venture outside that comfort hole - you might as well plant in a pot.

As to what to amend with, organic compost should be enough. Your soil already has plenty of minerals. I don't stick with one type or one brand and I use whatever is cheapest. Mix whatever you choose with at least 1/2 native soil (the native soil should be the bigger volume). You shouldn't need to fertilize at all for the first year, after that, time release is a good choice (but not Fertilizer Tree Stakes). Don't add sand, that will turn your lovely red clay into lovely red hardpan.

mycorrhizal fungi. i would highly suggest mixing this fungi into your medium and buffer and if you dont know what exactly the relationship in between the roots and friendly or should i say best friend fungi then i would look into it. its a great way for your tree to thrive and use rain water when watering it or a cheap alternative to your cities tap that would ultimately kill any microlife in your medium. i would also consider adding azospirillum brasilense too.

To:Daisyl
What are your professional accreditations/certifications?!!
Are you or have you been a certified horticulturist in any U.S. state? Because you seem to be on these forums on The National Gardening Association website quite frequently, always answering questions posted and I'm questioning whether you're actually a Master Gardener or not and shouldn't be giving out advice! This is the 2nd time I have posted on here my questions about planting bare root fruit trees and this is your 2nd time replying! Your answers are very vague and so, not explicit enough for me!
I said in this thread that I KNOW my native soil DEFINITELY needs to be amended because I KNOW it is not adequate for planting anything and needs added minerals because i have been gardening in it for years! You tried to SQUASH that idea twice!! I asked specifically WHICH minerals to use and you just ignore my question being hell bent on always using native soil exactly as it is! That's B.S.! You give incorrect advice according to my sister who is a long certified arborist and horticulturist. I also welcome the advice of "Botanically Baked" and I am going to research his 2 suggestions of additives that he gave me of which you left such a puzzled look in response to. UGH!

Celtsgrace, you may like to read this article by a PhD horticulturist and ISA certified arborist:

https://s3.wp.wsu.edu/uploads/...

I'm not sure I understand your question about minerals. Adding minerals is typically done with fertilizer. Do you not wish to use a commercial fertilizer? IMHO it is better not to fertilize a new planting and wait until it is more established but any negative effects would depend on how much fertilizer was used. Too much and it can interfere with water uptake. Also some minerals may leach away before the roots can get to them.


I'm tempted to ask why you do not ask your sister this question

I will, gently and respectfully, suggest that you treat people attempting to answer your questions with a little less acid. IMHO, Daisy does not deserve to be treated in such a manner. If you don't like her answers, or anyone else's, my suggestion would be to skip them and move on.

My answer seemed pretty specific to me. As I haven't run out to your place and done a soil analysis, I can't tell you what it is missing. I stand by my answer but thanks for asking.