Ideal grain size curve for garden soil- is there one?

I am used to thinking of and classifying soil as a grain size curve, or as percentages of different constituents: boulders, cobbles, gravel, sand, silt, clay. I might break those down into fine/medium/coarse. I can usually guess the grain size curve within 5-10% of the soil test results, so if I was to buy property, I would probably bring a shovel and check the soil. But I don't (other than not all gravel/rocks, and higher organic content is better),know what I should look for.

Obviously, higher organic matter (min 5-10+%) is key to good soil, as are healthy fungal life, etc. But I am curious about the non-soil portions.

Is there an "ideal" or several ideal mixtures of the non organic portions? Is a wide, distributed  grain size curve (well graded/poorly sorted) soil best, or a poorly graded/well sorted -all one size- soil better or ....?

Typical/idealized curves-how I think of soil

My soil series covers all of these questions.

Redhawk

Redhawk- I looked through your soil series. A lot of it needs a third or fourth read for me to really digest it, but I didnt find information about grain size specifically.  

Would you mind pointing me to which of your threads has the information?

I suspect the "dead" parts of soil may not be a major research interest for you, but I am just very curious, as I know first hand how the particle sizes of soil are linked to their behaviour as a mass, and grain sizes (along with some mineralogy/smell) is something I can assess without a microscope/lab testing.

A good soil base (the broken down rock minerals we call dirt) consists of 1/3 clays (1-7 micron mesh), 1/3 silt (8-12 micron mesh) and 1/3 sand (13-23 micron mesh). Soil requires additions of organic matter, bacteria, fungi, and the other beneficial organisms both micro and macro organisms. Any mineral particles larger than sand serve as mineral banks for the micro orgaisms of the microbiome. I tend to recomend 10-20 percent organic matter and small stones as acceptable in garden beds.

I try to sive the base material of my garden beds
With 1/4 inch mesh screens this seems to be the best method for a soil that grows root vegetables well. Trees don't need anything but large rocks removed from the planting back fill.

Redhawk

Thank you!

I was speculating ideal would be pretty sand rich, maybe 50-60% sand, 30-40%silt, 10 % clay, (I am biased against clay though I know it holds nutrients, so even that sounded like a lot). Good to know I was incorrect. Adding organic matter/life to soil is pretty achievable with time and effort on a human lifespan timescale but breaking down rocks isnt really.

I have been googling and the answers were pretty unsatisfactory/unspecific (not heavy clay, not rocky, not pure sand- ok, those are bad, so what is GOOD, and how do you define any of the bad ones?)

So my current garden soil- a glacial till with roughly 10% clay,  20% small cobbles to small boulders, 10% gravel, 10% sand, rest silt (~50%), with <5% of the soil organic silt/clay - is deficient in sand and clay and organics, not just sand and organic matter.

Rocks i could remove, sand could be added if I wanted to use it in a raised bed, clay is harder to add but some organics break down to clays. Good to know. Thank you.

Organic matter breaks down into humus not clay, clay is rock ground into the smallest particles possible. Organic matter is easy to add, you can add it as a top dressing, as a thick layer of mulch, or spread a thick layer and use a garden fork or broad fork to work it into the soil. Organisms are easy to add by making a compost tea that has air added while brewing or add home made EM (effective microorganisms), or make the "biodynamic" preparations (I have my own method in one of the soil series threaads) and add those to your compost heap so the whole heap quickly becomes  rich in micro organisms.

If you are building and filling raised beds, using a cement mixer is a fast way to mix a good soil blend, then water with compost tea to bump up the microbiome.

Redhawk