newbie clay soil struggle

Colorado Clay; slimy when wet and cracked when dry

So would all ya'll suggest inoculation with mycorriza or compost tea *prior* to adding 6 inches of wood chips?  Was thinking about inoculating and then spraying with milk/molasses before I added the wood chips.  Or just spread the wood chips and let nature have its way?

Have already had the soil tested and added amendments (rock dust for minerals, sulphur for the extremely high PH of 8.4, blood meal and beet shreds)

Hi Caren.

I would add organic matter and probably gypsum. You're miles ahead by already having done a soil test.

The bacteria and fungi that soil macrobiota prey on require organic matter, so if you try to inoculate the area with beneficial microbes but give them nothing to eat, the net result will be less than spectacular. Add organic matter first.

I would also consider broad forking the whole area. Not inverting the soil structure at all, but just dropping the tines of whatever fork you're using into the clay and leaning back a bit on the handle to lift and aerate the clay in sections.

If you have organic matter and rock dust sitting atop your clay at that point, it will sift down into the cracks you make, increasing the ability of water and root systems to get down there, and physically holding open void spaces in the clay.

In some cases of calcium deficient clay soils, the addition of gypsum alone has fixed compacted clay.

Also, I wouldn't rototill the area. The fast-moving tiller can easily smoothe the clay at the bottom of its reach, moving your compacted clay layer problem down further, but making it worse. Water and root systems will take a 90 degree turn as soon as they hit that layer and start following it horizontally, limiting water retention and root zone growth both.

-CK

Chris, a lot of people suggest gypsum for clay soil. Is there a hard and fast ratio to put down on clay soils? How much per acre would you say?

That's why you want to work with a good soil analysis.

If you need fast remediation of a pH issue, I don't know if gypsum is ideal, as it breaks down slowly. I believe the deal with gypsum and clay is that the gypsum corrects calcium deficiencies that cause clay soils to become impermeable, though I might have the details wrong. If this is the case, a soil analysis would tell you about the calcium.

Bryant Redhawk is one to ask about the specifics. I am sure he'll chime in soon.

-CK

Hey Caren!

I applaud you for having a soil test done. It sounds like with the amendments you've added that the soil test indicated some deficiencies and you're taking steps in the right direction. That's important to address. Like Chris and Daniel mentioned, gypsum is the way to go to apply calcium to help loosen up that clay. Lime will add calcium, but will also raise the pH, which isn't what you want in your case. Can you share with us the amount of calcium and magnesium noted in your soil test? Does your soil test also list a Cation Exchange Capacity or CEC?

ph 8.5 (added elemental sulphur)
Electrical conductivity (salts) 1.4 mmhos/cm is low
Lime is 2 to 5% is high
organic material 2.5% woefully low (added compost and now 4 to 6 inches wood chips)
Nitrate 6ppm is low (added blood meal)
Phosphorus 7.8 ppm is low (added bone meal)
Potassium 416.4 ppm is high
Zinc .9ppm is low (added rock dust)
Iron 17.6 ppm is adequate
Manganese 3.3 ppm is adequate
Copper 2.2 ppm is adequate
Boron .5 ppm is high

You guys are awesome to help out!

Mycorrhizal fungi  feed on decaying organic matter as well as form symbiotic relationships with living roots.  Thus if there isn't organic matter on the soil surface or some sort of plant for them to create a bond with, at best the fungal spores will just lay dormant, and at worst, they will die, particularly if they are exposed to UV light.  If you are planting trees, it's a great idea to inoculate the root ball with mycorriza.  A mature forest will be fungal dominated—that is to say, there will be a greater presence of beneficial fungi in the soil than bacteria, and the plants/trees will lean heavily on these fungal networks to get the nutrients they need.

The life in compost tea is bacterial and will be most active in decomposing nitrogen rich biomass (as you would have in a compost pile).  So, again, if there isn't organic matter available, the microbial organisms will either quickly die, or will fall into a state of dormancy.  Like fungi, bacteria work in concert with plant roots but in a different way.  Plants secrete sugars and starches from their roots in the form of root exudates—plant "juices" that attract the microbes they want while repelling those they do not want.  A living root is putting out the welcome mat for beneficial bacteria.  When you inoculate the soil with compost tea, you give the plant an opportunity to "call" the bacteria that it wants and build a habitat for those microbes in the zone around its root system (what we call the rhizosphere).  The bacteria help the plant metabolize (that may not be the correct word --- uptake?) soil nutrients.

Clay particles are negatively charged and form tight bonds, one against the next.  Think of a stack of paper plates.  You can't wedge much in between them.  Even if bacteria or fungi work their way between these chains of mineral particles, what is there to eat?  The solution is carbon, which breaks up the extended chains of clay particles.  Jelly-like "blobs" of humus mixed into the clay will transform your slimy and crack-y clay into rich, black, friable, crumbly soil.  Thus, whether you are trying to build fungal networks or a healthy bacterial community in your soil, both organic matter (mulch of some sort) and living roots are essential.  Cover cropping is a great way to encourage the growth of both.

That was a long-winded answer to basically repeat what Chris has said above: build the home for the microbes to thrive FIRST, and then inoculate your soil after.  If you can both add organic mulch (like wood chips) AND plant a cover crop, (particularly a multi-species mix of cool season and warm season plants, both broad leaf and grasses), your soil will be a wonderful habitat for either fungi or bacteria.  

Let me throw one more thing out there.  Once you've created a biologically rich living habitat for microbial life, the need to repeatedly inoculate your soil is unnecessary.  In fact, its my opinion that teas and other amendments are a lot of effort for minimal gain, whereas a cover crop is a gift that keeps giving to your soil for months.  That's just my perspective, but if permaculture is a design system that mimics nature, you don't see someone doing foliar sprays in a forest or savannah grass land, yet the soil is teaming with life.  Effort put to increasing the quantity of plant diversity growing in your soil as well as increasing the amount of leaf-litter and biomass on the soil surface will continue to feed the soil for years.  I'm not anti-compost tea, but I'm anti-extra work.  Cover-cropping as well as chop and drop mulching accurately mimic nature with a fraction of the effort it takes to brew teas and spray them.

Best of luck.

Caren Pilz wrote:Colorado Clay; slimy when wet and cracked when dry

So would all ya'll suggest inoculation with mycorriza or compost tea *prior* to adding 6 inches of wood chips?  Was thinking about inoculating and then spraying with milk/molasses before I added the wood chips.  Or just spread the wood chips and let nature have its way?

Have already had the soil tested and added amendments (rock dust for minerals, sulphur for the extremely high PH of 8.4, blood meal and beet shreds)

Here's the thing with clay soils, you will waste any inoculations if used prior to increasing organic material content first.
The reason I say this is that clay will repel anything laying on its surface (think piece of glass), so if you want to make amendments before you add something like wood chips, compost or any other organic matter it will roll off and be wasted.

First you add your organic matter (My favorites include coarse compost, wood chips, manures mixed with straw or hay) by getting the organic materials into the clay, those microscopic sized particles of clay have something to cling to instead of clinging to each other.
This allows spaces within the clay for air and water, that means that when you then apply a liquid like compost tea it can start sinking below the surface right away rather than laying on the surface or sliding off the surface.

Here's a "way to go!" for getting the soil tested and starting the amendments, by the way, I really like the use  of sulfur to adjust the pH.
Gypsum will help condition the clay but once again you need some organics in there first, that will allow the gypsum to really do the job you want it for; adding calcium and slow pH adjustments along with increasing your CEC ability.

Once you have the organics in there, do add some bacteria through teas and I also suggest you find some mushrooms and make a slurry to pour on the area as well, the double hit of bacteria and fungi is a powerful soil building mechanism.
As Marco mentioned, get something growing in your new soil, that does far more good than anything else, but with the additions, you will get there faster.
We use compost teas to increase the microorganism numbers, not just bacteria but all the organisms that live and work in our soil can be increased with properly brewed teas and extracts, an extract is just a super concentrated tea by the way, both need oxygen to brew properly.

Redhawk

Agreeing with everyone about amendments for nutrients and I'd like to add my experience with red clay in a 2000 sq ft garden for 5 years.  To turn clay into a nice loamy soil at a ratio of 40% sand, 40% silt to 20% clay, a huge volume of organic material needs to be worked in.   This is extremely labor intensive so I highly recommend building up from the clay if you can, and agree with the warning that tilling will alter the natural retention and flow of water.   I tilled the first 2 years resulting in only temporary improvement before I discovered permaculture and for 4 years since then,  have been piling on compost, leaves, hay, straw, green clippings, woodchips, etc.  Although it was turning brown and more friable, it's still heavy.  Muck in wet winter and dry as a brick in summer if I don't keep it heavily mulched.  

You don't say whether you're farming or starting a small backyard garden but either way, just start piling on as much organic material as you can.      

In addition to green stuff,   I've found that leaf mold is the best to attract worms and retain moisture (thank you Ken Peavey here on permies) and woodchips are the best for creating compost (thanks Paul Gautschi "Back to Eden").  Both of those need about 3 years to decompose sufficiently to start seeds or seedlings so when I plant,  I pull back the top dressings and dig out a shovel full of the established dirt and replace with a shovel full of fresh loam (either from the store or your own finished compost).  (many threads here on this subject).  Then I apply 3-6" of hay or straw leaving an open circle round each plant (hay is longer lasting and better for moisture retention).   Then in the Fall I add 6-12" of leaves and woodchips on the surface, without mixing it in.

(Edit to clarify timeline and add this sentence:)   I forgot to include the addition of SAND.  Complying with ratio above, just two years ago I started adding 40% sand to each shovel full of compost when planting seedlings, and in the fall I add about an inch of sand on top of the bed.   After one year, improvement in friability is HUGE!   Probably one more year of adding sand will be sufficient and I'll stop.

In the city, I started collecting bags of leaves from residential streetsides every November, until I found a lawn service company that brings me a tandem dump truck load of leaves already chopped :)  Once a year I receive a tandem load of woodchips (mostly oak and maple here) from a tree service free -  that I apply 6" thick on my paths and as mulch for my shrubs and perennials, and mix in with a 3 yr compost pile.   I go out of the city to get a carload of hay from a nearby farm

And check out the many threads here about how good chickens are for "tilling" your soil and adding manure - especially for starting new garden beds.  
Best of luck and keep coming back  - there are so many helpful, knowledgeable people here who have helped me "see the light and grow" in many ways :)

I've had good luck following advice similar to the above - amending with wood chips, leaves, barn waste, mushroom slurry & etc. and would like to add two things-

First, I scatter used coffee grounds on soil where the ph is higher than the plants I want there prefer. I also just realized i've never re-tested the amended soil, and will add a before/after comparison test to my to do list of for this year. All I know is the strawberries did well. I found a ready supply from the coffee machines at work, and there's plenty more for the asking at my favorite local cafe.

Second, I amend with charcoal at a ratio of 1 part charcoal to 5 parts organic matter (-ish, this isn't a chemistry lab). BioChar is the trendy search term, but go to the barbecue aisle instead of the gardening aisle if you're buying it from a store, where the same product is often sold much cheaper as "lump charcoal" (NOT briquettes!). I add charcoal because I can't get enough organic matter from a clean source, so -especially the barn waste- often has persistent broad-leaf herbicides in it. Paul discusses the problem in several podcasts and videos. I can't follow his suggestion of only using on-site feedstocks; chop-and-drop is not a viable strategy when all I have is tumbleweed. BioCycle suggests the 1:5 charcoal amendment as a remedy based on experiment by commercial composters. I don't have enough data yet to confirm or disprove, but I'm working on it. I got a small harvest in year 1, and the greens I'm overwintering don't look too cranky for January.    

On another scale, in my wee garden, I twiddled around foolishly with my clayish soil (though I've got a great pH - about 7) until I discovered permaculture (tho it seemed to me at the time "too complicated" to apply a full scale design) and Lasagne planting (which was immedialtely comprehensible and applicable). I just layered on my lasagne material (= ANYTHING you can get your hands on FREE) and planted - in my amateurish way, knowing nothing really about gardening, with various success levels as to harvesting, but anyway, things grew. I add leaves from my street in the autumn, and grass clippings or leaves or wood "chips" or bark or whatever as mulch when planting, and compost for those who want it. What I very quickly became proud of was the way as the years go by the clay soil UNDER my lasagnes (or beds as they are now or mini-swale mounds as they are about to become) gradually turns into lovely soft loam, an inch or two per year, without me doing a thing (except disturb the soil to see, or usually to show others, what's going on). As I get my act together learning to grow vegetables and perennials, to understand the permaculture principles and begin to understand the needs and interactions of the living things I'm working with, and preparing for the (2) chickens I've been planning for years, I am able in the meantime to be delighted at the fact that my garden is busily growing SOIL.

Caren,

Your soil sounds a lot like my Southern Illinoisan clay.  It is wet and slimy after during rainy seasons and brick hard in hot seasons.  When I first started my gardens in clay, I tried to use just a spade to double dig a few beds.  I could not even dig a single 6'x20' bed and quit due to exhaustion.  I broke down and bought a cheap tiller (I know, hardly a permie solution) but I HAD to do something to break up that clay.  My first year I did add commercial potting soil and bags of manure to plant the actual holes for the veggies.  Later that year (fall), I raked leaves from every neighbor that would let me, dumped those leaves on the beds about 1' thick and took the tiller to them again to work them into the soil.  After this second tilling, I never used the tiller again and sold it a couple of years later as it was just taking up space in the garage.  Today, were I doing the same thing, I would have dug up my bed with a 6" grub hole from Here:  https://www.easydigging.com/grub-hoe.html

Moreover, I did invest in a drip irrigation system from Here:  www.dripworks.com

I found that the more I irrigated, the less I needed to.  My leaves were breaking down, the soil held moisture in the summer from all that organic matter in the soil.   The soil was less than perfect, but it did get more fertile and more workable as I planted more crops, I found that the root systems were getting increasingly massive--and those roots really helped to both break up the soil and added precious soil carbon--a natural coil contitioner, excess water holding material and home for microorganisms.  

My beds are not perfect today, but they are a far cry from the old hard-as-brick solid clay I used to have.  Were I doing this over again, I would add hefty amounts of biochar to the soil before I ever turned the soil over.

I hope this is helpful, and If you have any questions, feel free to ask.

Eric