Replacing soil ?

Hello everyone,

New to permies and have a project going and could use some input.

We live in the California Sierra Mountain Foothill elevation 2800.  The soil has poor drainage and we we have several seasonal streams that move a lot of water.  In a portion of our 40 tree orchard area we are planning to add Almond, Walnut and Pistachio trees. I read about the root system requirements for the walnuts being 5 feet and 3 feet for the Pistachio's of penetrable soil. Knowing the decomposed granite / clay we have, I decided to dig out the soil(hopefully getting through the hard pan) with plans to amend it with wood aged wood chips and manure and then replace it and raising it about 2 feet higher than original. I plan on creating 2 foot mounds added to that so that the surface roots will be above grade.

Even with a tractor this is a lot of work and a lot of soil to deal with. At this point I have rug down about 3 feet for the planting area which is about 1,500 sq feet. (about 165 cubic yards)  Should I continue the trudge to get to 5 feet or is it unlikely that there would be a noticeable difference?

Thank you in advance for the input,
Don

Most of the top 10 feet of the Sierra Nevada mountain range is fractured granite, roots can get into the fractures and they will continue to widen those fracture lines.
Now, if you are wanting to use a lot of fuel and effort, then what you are doing would be worthwhile except that making hugel mounds is not how to plant trees, the hugel will eventually collapse and the tree will topple.
When you want to plant a tree, you want a stable surface, not something that is bound to collapse. If you really want that extra two feet for the roots, you will need to use stone and mortar to build giant "tubs" for each tree to live in. A lot of work indeed.

Why not simply use the land as it is, plant the trees and keep them watered until they have established nicely at that point they will have roots anchored into the granite bed rock and you are good to go.
More important than the soil depth is what is living in that soil, all the trees you mention require mycorrhizae to flourish, so make sure your tree's roots have access to these fungi and then add a compost mulch to prevent moisture loss and add organic matter to the soil.
By the way, granite soils tend to be acidic, so do get that tested or buy a kit and do it yourself so you know the starting base line then you can check it yearly to see how things are changing.

Redhawk

The work has already been done. I stopped at about 4 feet. Every tree has a requirement for soil depth. It is not uncommon to rip down 2 feet or through the hardpan to make sure the root system has deep soil for robust growth. Didn't do it before, because I didn't have a tractor. It was purchased to do this type of work. If the backhoe was working I would have gone deeper.

As an example
http://ipm.ucanr.edu/PMG/GARDEN/FRUIT/CULTURAL/avocadosite.html

Lots of info to read out there on this topic. Not making a mound, but rather dug a hole like a swimming pool. I am filling it with a combination of the native soil, aged wood chips and manure. The tree mounds will be about 8 foot circles and I am raising so that the root system is above grade to prevent root root. We have lost quite a few trees do to root rot as the whole area became a swamp.

Pics attached of a typical winters water plowing through and of the hole.

Thanks for the input,
Don

I hope the manure is composted as I would have concern about all that nitrogen turning to ammonia.  To really help the trees and this was already stated above.  Change the soil life from more a bacteria based soil to a fungal based soil as the trees like fungus based rather than bacteria based which is more for fields.

Their are a variety ways of doing that.  I recommend a natural farming technique called IMO.

Here is a link to that information:  http://culturalhealingandlife.com.www413.your-server.de/index.php?/forums/topic/45-inputs-section-10%C2%A0-imo-to-imo-2-how-to-capture-and-cultivate-indigenous-microorganisms/

Thank you for the  link and info. I will read it over the weekend. Most of the manure has been in a pile for a couple of years. The newer stuff is a small percentage of the whole and is closer to the base of the hole.

Bryant RedHawk wrote:Most of the top 10 feet of the Sierra Nevada mountain range is fractured granite, roots can get into the fractures and they will continue to widen those fracture lines.
Now, if you are wanting to use a lot of fuel and effort, then what you are doing would be worthwhile except that making hugel mounds is not how to plant trees, the hugel will eventually collapse and the tree will topple.
When you want to plant a tree, you want a stable surface, not something that is bound to collapse. If you really want that extra two feet for the roots, you will need to use stone and mortar to build giant "tubs" for each tree to live in. A lot of work indeed.

Why not simply use the land as it is, plant the trees and keep them watered until they have established nicely at that point they will have roots anchored into the granite bed rock and you are good to go.
More important than the soil depth is what is living in that soil, all the trees you mention require mycorrhizae to flourish, so make sure your tree's roots have access to these fungi and then add a compost mulch to prevent moisture loss and add organic matter to the soil.
By the way, granite soils tend to be acidic, so do get that tested or buy a kit and do it yourself so you know the starting base line then you can check it yearly to see how things are changing.

Redhawk

Are there test kits that you can buy that will get the job done or should I just plan on a lab. Can you suggest a lab?

Thanks,
Don

Step one is done. Dirt mixed with manure and wood chips and the whole filled. (pic attached)

Next step is going to be grading it. My plan was to grade the slope towards the hill (West - right side of picture) for water retention and from top to bottom of picture on the right for runoff. Make a ditch where the water would flow and fill it with rock making a new stream that runs into a pond that is yet to be built which when overflows will feed a stream behind the hugle bed. Once graded I am going to continue to build it up more by hand than tractor for better control. and to minimize compaction.

If I am going at it wrong, please let me know. Everything we have been doing is a result of a lot of reading and changes made to previous failures or partial failures.

Thanks,
Don

Donald,

You certainly have a project ahead of you, and given that you have already dug and added chips, the next step I would take would be to add in as much microbial life as possible.  I think that you are right that you need to control the small river that runs through your patch as it does now.  No sense in trying to improve your soil if it just washes away.

Once you get your ditch dug, I would think about planting a cover crop.  I say this as a cover crop will help stabilize that freshly turned soil.  Additionally, you can probably pick a cover crop that will add some fertility to the soil and aid freshly planted seeds.  In the last year or two I have come to believe that one of the worst things you can do for your soil is to let it sit bare.  At the very least I would try to cover the ground with woodchips, but I think a living cover crop would be better.

I have recently (last year or so) come to realize how important soil microbes are,  I am growing in a bunch of woodchips inoculated with mushrooms.  I am using wine caps, but perhaps you could find something more appropriate for your orchard (but personally I am finding wine caps to be unbeatable but I am just starting my fungal journey).

Another trick you could try is to build a compost pile (or perhaps more than one).  This is not so much for the compost itself (though that is a bonus) as for what the compost pile does for the ground beneath.  I once had to pile a bunch of grass clippings in an out of the way place so I piled up the clippings (about 5’ tall by 6’ at the base) near a small orchard.  Really, it was a poor compost pile, it was not balanced, nor did I turn it, and it eventually rotted down to nothing.  But the nutrients and microbes ran gently down hill about 15’ and encompassed a baby peach tree.  That peach tree grew twice as fast as it’s neighbors and is still the best tree in the orchard.  This happened by accident, pure and simple, but I believe that if you were to put one in deliberately you could get even better results.

Ultimately I would try to get as much life growing in that ground as possible and I think a cover crop would be a great start.

Best wishes and please keep us updated.

Eric