working with clay soil

[begreen]

Good point. You can buy “soil” now that is often referred to as a three (or more) way mix of things that the yard had. Our local manufactured soil is sand, sawdust, and compost.

Compost for this context is 100% organics and not mineral soil. Think rotten bark mulch, leaves, or other ground up vegetation. Manure is vegetation ground up by animals.

Is that what you used bg?

Yes, not a mix, pure compost. Just not sure what the farm reference is about.

 

[begreen]

Keep in mind that some of these things, esp. wood products like sawdust or decomposing mulch, leach much of the nitrogen out of the soil, that you want to save for the stuff you’re growing. Manure and peat are better soil modifiers, than sawdust or mulch.

That hypothesis is debatable and may depend on the composition of the mulch or sawdust. Some soil scientists will say it is a myth. In general proper application of a wood chip mulch, particularly hog fuel chips, can be quite beneficial for soils, especially when limb bark and leaves are shredded. For certain nitrogen is not leached. In some cases it may be bound up temporarily, but the increased microbial action with a good mulch releases nitrogen over time. Sawdust will bind it up more efficiently, but this can be counteracted with the addition of a nitrogen component like manure. The benefit is that this nitrogen is bound to the soil and does not leach out readily. Artificial nitrogen from commercial fertilizers on the other hand always will leach out of the soil, most quite quickly.

https://s3.wp.wsu.edu/uploads/sites/403/2015/03/wood-chips.pdf
(broken link removed)

I have a test bed in our raised garden beds in which anaerobic digestate (short term nitrogen and phosphorus source) is combined with sawdust and composted. I applied about 4" to the 16" deep bed and mixed it in well 2 years ago. The results have far exceeded my expectations. It has outperformed the other beds in many ways. Root crops have been outrageous in this mix, especially potatoes. The yield and size of the potatoes is outstanding. The other phenomenon I am noticing is how moist the soil is in this bed compared to all the others. We are in a drought and struggling to keep plants adequately watered, The test bed gets the same amount of water but it is totally different, with a wonderful tilth that is evenly moist throughout. The results are so impressive that I am considering applying this mix to other beds as this is now our 3d drought summer and each year gets worse.
https://www.motherearthnews.com/org.../building-garden-soil-wood-mulch-zmaz10onzraw

 

[Highbeam]

anaerobic digestate

I use a lot of that. We affectionately call it butt dust!

 

[peakbagger]

The gold standard for soil conditioning is Terra Preta. https://en.wikipedia.org/wiki/Terra_preta. Its charcoal that has been heavily amended with organics. The charcoal acts like activated carbon and attract and binds nutrient from leaching from the soil. I have run into individuals at various shows that make there own and make some pretty incredible claims. I have seen samples and the resulting soil is has very low density and will not pack. Clay soils are composed of very fine soil particles that pack tightly and do not allow roots to form and have drainage issues. Gravel drains great but the nutrients dont bind to the soil particles. Some hydroponic operations used to use gravel as bedding material but they keep a constant drip of nutrient solution running so the bedding is just acting a matrix for the roots. Terra Preta acts like gravel with good drainage but the pores of the charcoal absorb moisture and once its precharged with nutrients from the organics mixed into it it is net nitrogen contributor.

 

[begreen]

Soil is a complicated environment with many factors working together to make it a healthy living ecosystem. The test garden project I am managing is exploring yields with different crops in soil amended with biochar vs not amended. We're wrapping up the 3d year now. I'm also subscribed to the NW Biochar group and have some close friends that are hard core biochar advocates. Some of the claims are true and others are sometimes exaggerated or have have other factors done to the soil at the same time, so the effect can not accurately be attributed to just the addition of biochar.

So far our test garden results have been mixed. Some crops have responded well to biochar and others have not so much. The potato plots did notably better (up to ~25% greater yield) with in the biochar amended plots, but less so when a nitrogen source was added (bloodmeal). Last Friday I harvested 251 pounds of onions and with the exception of one block, the plots without biochar had notably higher yields. That said, there have been some good studies by Humboldt Univ. that have demonstrated significant gains for forest recovery using biochar. Lots of research still happening on biochar and every year we are learning more. It's not a universal panacea as some initially thought, but it is an important amendment in some cases.

Note that it's not untypical to have lower yield the first year in the biochar amended soil. There are several theories on this, but recently electron microscope studies show that during the first year microbial colonies are growing and developing in the cells of the char. There is also a pH balancing that happens in the first year. Here are some shots of the garden. It started out at poor, clay fill dirt and now is very productive soil. All of the harvest goes to the local food bank.

 

[peakbagger]

Nice of you to supply the local food bank.

I cant remember his last name but there was someone we worked with out in Northwest called Tom that was biochar guru.

 

[AlbergSteve]

Many universities offer comprehensive soil testing. I like UMass because of their testing methods and good track record, but I am no expert. Before starting our test garden project we pulled together a panel of scientists. They went over many more variables primarily focused on the health of the soil. The agricultural philosophy is changing from feeding the plant to feeding the soil, which is a complex and very alive entity. It was this panel that recommended UMass Amherst for testing.

While there are some similarities, turf management and food garden management are not exactly the same. Testing methods may vary as well as the report advisement. It's good to let the testing company know which is being tested. Some testers will have a place on the form to indicate the purpose of the testing.

Bit late to the party here, but we had our soil tested earlier this year. We have 2 acres with about 1.5 that we will plant out in garden beds and orchard.
We spent yesterday blending amendments and tilling them in with compost.

First, doing the math and measuring...



Spreading "evenly", then cover with compost...



Then letting that big Barretto tiller throw me around for and hour!

 

[AlbergSteve]

Gypsum is lime, asphalt is neither

Nope, gypsum isn't lime. Lime is calcium carbonate and gypsum is calcium sulphate.

 

[begreen]

Nice of you to supply the local food bank.

I cant remember his last name but there was someone we worked with out in Northwest called Tom that was biochar guru.

Tom Miles? He is on the International Biochar Initiative board.

 

[peakbagger]

Tom Miles? He is on the International Biochar Initiative board.

Yup he is the one

 

[iron]

reviving the thread...

i'm not as concerned with the clay in my soils now. after a few rains, it drained fine, and after i build up the yard with another 2ft of fill, i think water will have plenty of ways to run if it doesn't like the clayey areas of fill i've dropped in.

now, i think i probably need 40-50 yards of more fill. getting free fill is hit or miss, and quality is generally low. i'm thinking of using "pit sand" per this supplier.
http://fruhlingsandandtopsoil.com/home/products

thoughts on if this would cause an issue? i'm thinking pit sand everywhere and then top it with 4" of 3-way soil and 2" of 2-way soil before hydroseeding. basically, 6" of dirt on top of pit sand.

problematic?

 

[semipro]

"Pit Sand" sounds to me like what we call "crusher run" or "crush and run" here. The mix of fines and gravel packs very well and will form a stable structure that should drain well. I suspect if you cover with enough organic material it will suit your needs well. In general I think turf roots are relatively shallow while other plants root deeply (mesquite roots have been found at depths over 200 ft. in Texas).
I think you're on the right track. Adding too much organic material at depth will lead to subsidence as the organic material degrades.

Edit: Looking again at the options at your link I can't see why the crushed brick wouldn't work as long as it contains enough fines to stabilize it. Its a 1/4 the price of the pit sand.

 

[iron]

"Pit Sand" sounds to me like what we call "crusher run" or "crush and run" here. The mix of fines and gravel packs very well and will form a stable structure that should drain well. I suspect if you cover with enough organic material it will suit your needs well. In general I think turf roots are relatively shallow while other plants root deeply (mesquite roots have been found at depths over 200 ft. in Texas).
I think you're on the right track. Adding too much organic material at depth will lead to subsidence as the organic material degrades.

Edit: Looking again at the options at your link I can't see why the crushed brick wouldn't work as long as it contains enough fines to stabilize it. Its a 1/4 the price of the pit sand.

yeah, i've thought about the crushed stuff. my concern is that, while cheap, it will be harder to handle. i'm doing all work by hand with a yard cart and shovel. so, scooping into angular material is much harder (and louder since i do my work at night after putting my 2 y.o. daughter to sleep)

 

[peakbagger]

Funny "Pit Run" in my area is defined as whatever comes out of the pit with no processing. Most of the pits in my area are glacial outwash and frequently they end up with a fine sand with rounded rocks and pebbles mixed in that drains well but doesnt pack well. Its useless for driveways and is cheap as most pits do not have much of a market for it. Crusher run is made from larger rocks that has been crushed in a plant. The resultant broken rock is angular instead of rounded. There are multiple specs for the crusher run depending on the size of the crushed rocks and the mix of sizes. Crusher run can make great driveways but if it is put on top of clay or silted soils, freeze thaw will eventually work the silt up into the gravel and turn it back into mud. For roadwork the solution is lay down a layer of geotextile on top of the clay/silt and then put the gravel on top of it. The water drains through the fabric but keeps the silt from migrating upwards.

 

[AlbergSteve]

Funny "Pit Run" in my area is defined as whatever comes out of the pit with no processing. Most of the pits in my area are glacial outwash and frequently they end up with a fine sand with rounded rocks and pebbles mixed in that drains well but doesnt pack well. Its useless for driveways and is cheap as most pits do not have much of a market for it. Crusher run is made from larger rocks that has been crushed in a plant. The resultant broken rock is angular instead of rounded. There are multiple specs for the crusher run depending on the size of the crushed rocks and the mix of sizes. Crusher run can make great driveways but if it is put on top of clay or silted soils, freeze thaw will eventually work the silt up into the gravel and turn it back into mud. For roadwork the solution is lay down a layer of geotextile on top of the clay/silt and then put the gravel on top of it. The water drains through the fabric but keeps the silt from migrating upwards.

Yep, and that's what we call pit run (glacial till) here on the Island.