Rick, I am tired just reading your post! I know it's a lot of work, but it is worth it. You are very dedicated to do all that!

Bit, it is very amazing the difference from area to area! Still, I think it's easier to add compost to sand than try and amend clay!

I'm not sure which is easier. Now that I know that clay gets softer when it's slightly moist, I can manage it.

For me, the limiting factor is how fast I can make, buy, and wheelbarrow compost around my yard. I've heard that organic matter is consumed fastest in warm, well-aerated soil (like sand). My clay take about 18 months to revert after I add compost. How long does your compost last in sand: 18 weeks?

Oh yes, I agree wholeheartedly! While something more organic-rich would be ideal, I actually don't mind my sand. It's easy to dig and root crops (which are some of my favorite crops ) grow well in it. Any soil benefits from amending, but reading through Rick's tribulations, I'm glad that I only have to amend for nutrients and not for texture.

>> I'm glad that I only have to amend for nutrients and not for texture.

That's great!

I'm fumbling my way toward a theory about how to make good soil. It would have stages or aspects of soil that must be satisfied.

Mechanical
Chemical
Biological
Interdependent (holistic)

1. Mechanical structure
Grain sizes, drainage, aeration, friability and "tilth". The grains and fibers need to be coarse enough to allow both drainage and retention (excess water drains out, but enough is held between rains) and aeration (air can perk in and CO2 can perk out).

Stickiness may help or hurt: it might help form beneficial crumbs or make clay so sticky and dense that nothing can pry it apart, Soil must not be so sticky that it is not friable.

There is something like "stiffness" that allows soil to "stand up" around a void instead of slumping and flowing to fill the void. I think that is the opposite of "pliable".

Grain shapes that are elongated and twisty and interlock help prop the soil up better than ball-bearing-shaped grains that wash out easily so that they flow into voids and fill them .

Mechanical structure could be completely inorganic, except for the facts that roots add structure, and the breakdown products of organic matter (and worm castings) probably help soil 'clump' and form into 'crumbs' or peds.

We usually talk as if healthy soil forms discrete crumbs that sit on top of each other like golf balls, with continuous, connecting open spaces between balls of soil.

My theory instead is that "crumb structure" should be called "interstice structure". I think that, when soil is appropriately sticky, it gloms together so as to support many small, individual crevices and voids that don't necessarily interconnect, but instead scatter and wind through a mostly continuous phase of solid soil.

Like ponds and short streams dotting a solid landscape. Not like islands of soil spotting a continuous ocean.

When we try to build "crumb structure", we're actually trying to make the little voids stable enough that they don't slump or shrink out of existence.

2. Chemical aspects of good soil

These are the easiest to fix if they are out of balance. The only hard part about chemicals is having the restraint to avoid using TOO MUCH.

Air (Oxygen and Nitrogen) - - - not enough oxygen drowns roots dead.
Water - - (enough but NOT TOO MUCH - too much water drives out air, then roots drown)
pH.
Mineral Nutrients:
- majors: NPK (avoid TOO MUCH, especially too much Nitrogen)
- semi-majors: like Sulfate, Iron, Magnesium and Calcium (keep them soluble with pH and no excess nutrients)
- micro-nutrients like Copper and Boron and at least a dozen others

Mineral and Chemical Toxins
- salinization: excess Sodium and Chloride, or any salt or fertilizer in, kills plants by preventing them from taking up water
- herbicides, heavy metals, almost any chemical: too much is harmful or fatal.

Oh my. Too much for my brain. I can't get into it like that. Just know when it's too heavy or too sandy, and JUST RIGHT, but of course I'm strictly talking texture...I let my son worry about the rest.

Good post, Rick!

A note about "too much": it's almost impossible to get there with compost, well-rotted manure, or other slow-decomposing organic matter. Where people get in trouble is by adding nutrient sources that are too harsh (often described as "hot") such as fresh manure or high-NPK chemical fertilizer.

In my garden, I like to get most of my nutrients from compost and plant matter, but when things need an extra boost, I'll add a bit of pelleted chicken manure. The NPK (Nitrogen-Phosphorus-Potassium) varies a bit by brand, but is in the 4-2-2 to 5-3-2.5 range. Compare that to Miracle-Gro at 24-8-16, and you can see why one is so much easier to overdose than the other!

We don't use and chemical fertilizers, just compost, well rotted horse manure and green manures. sometimes some chicken manure. But most of my compost is used for potting up plants and then a big scoop in the planting hole, mixed with peat, vermiculite, soil. (I actually use some of the clay soil to mix with the rest of the stuff. Can't add much though, just too heavy and sticky. I don't have enough to do all 40 rows as a top dressing, as much as I'd like to.

I actually meant "too much" as in, too much for my brain to absorb

Arlene, your reply wasn't there when I started typing, so I was actually responding to Rick's "NPK (avoid TOO MUCH, especially too much Nitrogen)".

Sorry for the mix-up, and I hope I didn't do additional brain damage

I know I should know more of the whys of things but sometimes I just want to grow stuff.

There's so much info out there, all our brains would explode if we tried to learn everything!

I have a background in science, so the chemistry comes pretty easily to me. Start throwing around traditional methods (what's the phase of moon got to do with it?!?!), and my eyes glaze over. And even though I spend my day with the Latin names of bacteria, I can't begin to handle all the hybrids and cultivars that exist among garden plants. We all have our own strengths and weaknesses, so go with what works for you

I thought I was a pretty advanced gardener until I came to this site. So much I DON'T KNOW!!! (Of course there's some I don't care that I don't know )

I'll just hop around the forums, read and research, then try and ask questions that won't seem too dumb.

I do have my experiences to offer though! even planting the rhubarb upside down!

==
Biological

Once you have soil with enough mechanical structure to let water out and air in, no toxic pollutants, and enough minerals to support soil organisms, you must encourage a healthy micro-herd by providing organic matter like compost. Bacteria, fungi, insects and worms eat the organic matter and convert it to humic acids that help ex tract soluble minerals from grains of rock.

A dense population of aerobic soil microbes tends to compete with and consume undesired microbes like plant pathogens and primarily fermentative anaerobic types.

Finally, worms and symbiotic root-fungi (mycorhizae) can thrive. Worms churn, grind and mix the soil and organic matter. This makes the organic matter more available to microbes. Worms drive tunnels through the soil, creating even better drainage and aeration., mixing the layers and carrying organic matter from the surface deeper into soil - literally tilling the soil like micro-plows. They excrete goo that lines the walls of the tiny tunnels they drive, which also helps bind soil grains into stable peds (crumbs, clods and the gaps between them).

Mycorhizae penetrate into root hairs, especially when soil nutrients like nitrogen and phosphorous are scarce. They form a mutualistic symbiosis with the plant, improving its resistance to some pathogens and stimulating its growth. They extend from the roots hairs into the soil, increasing the surface area of contact. The mycorhizae extract water and minerals from the soil and transport them to the root hairs where the plant can use them. Sometimes these root fungi extract phosphate when it would not otherwise have been soluble enough to be available to the plant (basic soil).

In return the roots provide some carbohydrates to the root fungus. Plants can live without these mycorhizal partners, but grow slower and are more vulnerable to drought and soil-born plant pathogens. The benefit is greatest in nutrient-poor soil. The mycorrhiza can also live in dependently, but seem to benefit from the plants supplying them with carbohydrates (perhaps especially when the supply of soil organic matter is low?)

http://en.wikipedia.org/wiki/M...


Interdependent (holistic)

Mechanical soil structure is absolutely necessary before aerobic life can penetrate the soil. And yet heavy clay would never let in enough oxygen by itself, and sand or gravel would ne ver hold enough water or minerals by itself to support much life or any higher plants.

Mechanical soil structure enables enough biological activity to occur that the soil structure is improved further. Roots help break hard soil up, then die and leave channels behind. That allows soluble organic matter and air to penetrate, which attracts worms, which till the deeper soil. Then roots can drive even deeper.

More plants grow, and return more organic matter to the soil as litter and humus. That stimulates more plant growth.

When air, water and organic matter are all present, microbes thrive that release humic acids, which slowly dissolve mineral grains, which releases P, K and other mineral nutrients, sustaining and stimulating more plant ghrowth.

Mechanical and biological aspects of soil combine to promote the chemical aspect, until there is no need for added chemical fertilizer. The soil has become a self-sustaining, self-improving, multi-species organism.

Sorry to run on and on and on in a thread about radishes!

But that's been simmering for a while and I just had to get it out while it was making my fingers itch.

I don't think there is very much there new to many people, but I wanted to say it all in one place. Its like a hierarchy of needs. For humans, that would be first air, then water, then food, then things like shelter and safety and companionship. It doesn't help to have food and a fine house if you have no air or water (yet air and water pollution seem to attract less interest than "House Hunters" and the food channel).

What leaves me in awe of soil is the way that so many different species and families co-operate without managers or planning meetings or congressional hearings. Roots need fungi need roots need soil structure needs worms need organic matter comes form plants that need all of the above. "Inter-dependent" doesn't say it strongly enough. They thrive together. It's really awesome.

They cooperate like that over every part of the planet that isn't pure rock, ice, concrete or poisoned with caustic. Even most human toxins will eventually be broken down by SOME microbe, and the party bootstraps itself from sterile grit to praie or forest. How cool is that?

And I can join in the fun with my compost heap and wheelbarrow and drainage ditch. Almost all I have to do is kickstart the mechanical structure, then add compost.

It's like Ben Franklin said about beer: "Beer is proof positive that God loves us and wants us to be happy."

Soil and plants are proof that God and/or evolution are awesome.

Much simpler and can enter my noggin! I did know a lot of that stuff, just didn't know how to say it. I think I'll copy your explanation so I can refer to it!

Thanks

Rick, I love your posts in this thread! So true about the inter-dependence, and we're (that is, the human race, not us ATPers in particular) only scratching the surface in understanding all the dependencies and interactions in a system as complex yet commonplace as soil or natural waters.

Since you mentioned rock, ice, and toxic waste... there are microbial communities in all of them! Concrete is the only one you listed I'm not sure about, but I know people who study and culture microbes from all of those other places, and some that are even less hospitable to life as we know it. Hydrothermal vents, for example, have temperature (3x the boiling point of water), pressure (50x what would kill a human), energy (no sun to fuel things), and chemical (toxic sulfides, heavy metals) conditions that would make it impossible for most organisms to survive a moment - but they're teeming with life! It was recently discovered that there are fungi in the solid bedrock under the deep ocean, previously thought to be inhabitable only by Bacteria and their less-well-known cousins Archaea. Polar ice can contain large amounts of algae - tiny plants that photosynthesize from inside their chilly prisons. Life really is amazing.

Arlene, not sure if you know this or not, but there are two icons at the bottom each post - a star and a thumbs-up. If you click either of them on your favorite post with lots of good info, you'll get a link in your profile so you can find it again easily. I'm not entirely clear on the difference between the two - I think perhaps only you can see your stars, whereas the thumbs-ups have a little number by them to let other people know you like a post.

bitbit said:

Arlene, not sure if you know this or not, but there are two icons at the bottom each post - a star and a thumbs-up. If you click either of them on your favorite post with lots of good info, you'll get a link in your profile so you can find it again easily. I'm not entirely clear on the difference between the two - I think perhaps only you can see your stars, whereas the thumbs-ups have a little number by them to let other people know you like a post.

Both can be accessed and reviewed from your profile page...under "some info about....."

So they're both public? What is the difference, in that case?

I think the star is a reminder; like a bookmark. The thumb is for passing along appreciation.

Bit, I did not know that! Thank you so much that will be very useful!