Soil test results have me wondering what to do or stop doing

Got my soil test back.  Did it in 2015 and again last week.  The 2015 sample was just after tilling up sod and collected by the missus so I'm not sure it was collected as perfectly as the sample I took last week.

2015 results:
pH:  6.0
P:    223 ppm (too high)
K:    121 ppm (good)
Organic matter:  2.2

2020 results:
pH:   6.9
P:    270 (too high)
K:   304 (too high)
Organic matter:  2.1

Hmm.  So I don't fertilize at all.  The things we add each year are:
3" of grass clippings and chipped up leaves in the fall
Compost from the chicken run (50 leaf bags of deciduous tree leaves plus a winter's worth of chicken poop and some coffee grounds, composted fairly well)
Compost from the cold composted garden scraps we do in the garden
Ashes from the wood stove
Last year we spread coffee grounds around on the beds, probably 35 gallons worth over a 60'x60' area.

I'm quite surprised that the organic matter went down.  I'm hoping the 2015 number was high due to grass in the sample.  But my current sample should be better due to no till and mulch and the like

The pH is getting to the high end of the range so we're not going to put any more wood ash on it

Is the wood ash also why the K is so high?  I didn't think we put that much on.  In the last three years combined we probably put 60 gallons of ash on a 60' x 60' area of garden beds.

Ideas on what I'm doing wrong?  Or how I could bring down the P and K and bring up the organic matter?

The wood ash definitely stands out as the K and pH culprit. Its possible that the chicken manure is adding more P than your garden is able.to use up, and since P is pretty immobile it will just build up if not taken into plants.

As far as OM, what is your soil like? If its quite sandy then getting some clay into the mix could help. If it's already heavy with clay you might try using a broad fork or some other tool to break some deep channels for water/air intrusion

Thanks S!  Does high Potassium present an issue?  One huge reason to have the chickens is for their manure.  I did also put their coop bedding (wood shavings plus poop - composted) on the garden last year as well.  Maybe that was a bit too much...

My soil is a sandy loam with a bit more sand than loam.  It's pretty well draining and has minimal clay content.

I also agree with S. Lowe about the wood ash increasing the potassium and the soil pH. Since you don’t fertilize (that means store bought inputs?), these mineral increases are coming from your locally sourced inputs: grass clippings, composts and ashes.

I also would think the organic matter would increase. Here’s what I think might be going on based on what I’ve learned about soil biology and chemistry. Nitrogen is being added, some from grass clippings, some from the fairly well composted chicken poop & coffee grounds, some from the cold composted garden scraps. Just like adding nitrogen to a compost pile gets the microbial activity ramped up and munching through carbon, nitrogen being added (intentionally or unknowingly), gives the soil microbes a kick in the pants, and they will munch through carbon, and one carbon source is some of the organic matter in a soil.  Farm land that is row cropped conventionally with synthetic nitrogen fertilizers for example have poor soil organic matter because of this same biological process in the soil.

Was there any more information on the soil test, like cation exchange capacity (CEC)? I think it’s important to remember that soil analysis, while handy and offering information to help one know where the soil water soluble minerals is at, is information used in conventional gardening and farming.  The soil analysis reports the P & K is “too high” - ok, but according to who? I think nurturing abundant soil biology is the key to having “moderators” keeping things in balance. And I see you’ve been nurturing and adding soil biology with those composts.

Ideas on what I'm doing wrong?  

I don’t think you’re doing anything wrong. I do suggest halting the addition of ashes as more wood ash lye can send that soil into the alkaline side of things in a hurry. Hope this helps Mike!

Thanks James!  The only other tidbit of info from the report is that the Texture is rated at a 2.  Whatever that means...  No table or other info in the report about Texture.

Thanks for the reassurance that I'm not doing anything terribly wrong.  I'll halt the wood ash for sure (luckily we haven't added it yet this spring) and just keep adding my on-site inputs.

Thanks team!

I'm not positive at what point Potassium levels would present a problem, but I agree with James that generally the "acceptable" range on soil tests was derived for use by people making decisions about how much mineral salts to add for a season and the ranges aren't terribly helpful for folks working on building intact, living soil systems as their nutrient program.
Given your sandy soil I am under the impression that 2% OM isn't too bad. I would recommend experimenting with top dressing some clay like azomite or montmorillonite clay. My understanding is that these colloidal clay particles get bound up with the biological goo from root exudates and the various microbeasties and create a more stable carbon bank. Some people (john kempf from aea for one) say that this is the process of building soil.humus. I have seen it work wonders on the structure and vitality of that bagged potting soil that is mostly peat and perlite.
Might be interesting to try it on just a part of the garden space and test again in 2 years or something

Mike,

Wouldn’t the excess P & K present a great opportunity to plant a good legume to add more organic matter and nitrogen all at once?

Just a thought,

Eric

I am incorporating some biochar in with the compost (starting this year).  I'll see if I can find some easy clay somewhere...

Thanks Eric, I do plant legumes in about 1/6th of the garden beds each year.  I could do more but I can barely eat that many beans as is :)  I haven't tried a clover cover crop or other nitrogen fixing non-edible because I'm not quite motivated enough to figure out how to fit it into my short growing season.

One other question Mike, are you concerned about the test results because you've noticed a not quite rightness in your garden? Or were you curious about the test results because you wanted to see what you had accomplished and the results gave you some concern?

If the latter I wouldn't worry and would keep doing what you do (especially because it appears "what you do" includes tinkering at the edges of your systems to find improvement) but if its the former I would definitely consider making some.changes. if I were you and was concerned I would look at using less of the ash and maybe incorporating what I did use into the compost first. Then I would look at making some change to the use of the chicken bedding (since those seem to be your two "big" NPK inputs), maybe using the spent bedding as the bulk of a "hot" compost that incorporates your ash and your "cold" compost.

The last thing I want to.point you toward, because o think its brilliant and he's brilliant, is Hugh Lovel's concept of the biochemical sequence. It's a really revealing framework of understanding how minerals drive plant processes and might give you another angle to approach your garden from that could help make those high phos and potassium reserves more readily usable by your plants.

Here's a link to an article about it (if you can find a high res version of the graphic its a neat little thing)
https://quantumagriculture.com/2016/04/27/hughs-best-article-ever-on-biochemical-sequence-and-plant-growth/

I would add less nitrogen, less compost and green stuff, like coffee grounds and grass clipping and alot of carbon. I say add an excessive amount of carbon, even if it reduces productivity for a year until it stabilize. Getting your organic matter above 10% would be awesome.
Biochar is great for that, do note that biochar might take a season to stabilize. If not made at the optimum settings it's pore space will have some organic hydrocarbon, that soil life will feast on, outcompeting plant roots. even without that the empty pore space will lead to an explosion of soil life, which uses up alot of minerals thus outcompeting plant roots. Once the biochar is charged it will however start creating a lot of soil life "manure' with lots of bioavailable minerals that the plants will love.

s. lowe wrote:One other question Mike, are you concerned about the test results because you've noticed a not quite rightness in your garden? Or were you curious about the test results because you wanted to see what you had accomplished and the results gave you some concern?

If the latter I wouldn't worry and would keep doing what you do (especially because it appears "what you do" includes tinkering at the edges of your systems to find improvement)

Definitely the latter.  I was getting a soil test done for the community garden so I figured I'd do one on my own garden.  I was mainly hoping to see the organic matter go way up due to how wonderful I am.  So much for that...

S Bengi wrote:I would add less nitrogen, less compost and green stuff, like coffee grounds and grass clipping and alot of carbon. I say add an excessive amount of carbon, even if it reduces productivity for a year until it stabilize. Getting your organic matter above 10% would be awesome.
Biochar is great for that, do note that biochar might take a season to stabilize. If not made at the optimum settings it's pore space will have some organic hydrocarbon, that soil life will feast on, outcompeting plant roots. even without that the empty pore space will lead to an explosion of soil life, which uses up alot of minerals thus outcompeting plant roots. Once the biochar is charged it will however start creating a lot of soil life "manure' with lots of bioavailable minerals that the plants will love.

Thanks S!  Why should I add less nitrogen?  Is it because it's eating up the organic matter?  I'll make more biochar this coming heating season (I make it as I heat my house).  How many gallons of biochar should I add to a given area of garden?  I don't even have a guess as to the right amount...

And why less compost?  I was thinking that compost didn't have much NPK in it, it was mainly there to provide beneficial microbes and organic matter...

Mike Haasl wrote:Definitely the latter.  I was getting a soil test done for the community garden so I figured I'd do one on my own garden.  I was mainly hoping to see the organic matter go way up due to how wonderful I am.  So much for that...

Oh I'd say it sounds like you're doing great. It reads to me like you just opened up a window onto all sorts of avenues you could explore to improve your system. I'd highly recommend the talks/books of Gary Zimmer to you as well. He farms in the driftless region of Wisconsin and has a really interesting and digestible approach to farming (though not any sort of permie approach really, very much field crop framework). He talks about the idea of "the soil biological flywheel", basically that biologically active soil that is fed the proper inputs will begin cycling nutrients more and more rapidly and this will produce good crops but doesn't build soil carbon. In his view you need to add lots of carbon with your fertility program for this reason.

It is worth noting that everything I've seen him speak on he is super happy to be able to get SOM numbers between 2-3% on any of his projects on Wisconsin so I dont see that number as being terribly problematic.

I am reminded though as I type this of a new approach I just encountered that is supposedly rooted in traditional northern European gardening practices. Its from a German language book that just got translated to English with the title Humusphere, and the author advocates putting the garden to bed in the fall with a thick mulch of fresh green matter. He talked about using either long grass or small tree branches. He talks about achieving crazy SOM numbers (I feel like he claims something like 15%, whatever it was it was a shocking enough.number that I'm dubious frankly) and shares a similar climate to you, although probably different soil type. I believe the authors name is Herwig Pommersch.

3 inches of biochar to a given area, sounds good to me.
3 inch of woodchip would be the next best thing.
And while 3 inch of compost is better than 3 inch of fresh manure (nitrogen), neither one of them brings up the amount of carbon in the soil as much as woodchip/biochar.

And yes nitrogen cause an explosion of soil life that depletes carbon, so we have to make sure we add an excess of carbon

Perfect, now I just need to round up 16 cubic yards of biochar...  The city near me stopped allowing people to haul away wood chips so that's not an option either  

Thanks for the explanation of why it's needed and how the N affects the C!  I'll just have to do what I can as I can...

Hi Mike,

My advice would be to have a complete soil test done using the Albrecht methodology (Logan Labs)

You are looking at only 2 elements but you need to get the complete picture of the mineral break down in the soil.
(What are the levels of the missing 13 other elements?)

Once you have that information you can make an informed decision on how to get the imbalance corrected.

If you get that right you will be able to grow a nutrient-dense crop that tastes better and is more pest resistance.

Cheers
Anthony  

Mike, wait until you have a windstorm with a bunch of trees down. Drive around and look for arborist or utility trucks clearing. Tell them there is a case of beer at your address. Get some beer. Stop buying beer when you run out of places to put the chips and they stop coming.

It doesn't hurt to test your soil every season if you are not familiar with how your soil trends, at least w/ just basic NPK tests etc. I so far have been able to figure out my plants' imbalances through inductive reasoning (in other words blowing it out my *** primarily) as in just guessing from things like combining a lot of kelp with hard water can result in a calcium toxicity for plants because kelp is rich in calcium, etc. Although I test too. Your soil is in the acceptable range of things but I understand your concerns. I believe that level of phosphorus kills fungi, which locks up more phosphorus. I hear differing levels are suggested as to when the fungi are actually killed by salty phosphorus. The high potassium is probably because your plants are not high enough quality to need that much of that element yet despite your inputs. You can try a compost tea to attempt to get the beneficial fungi cycling the phosphorus again and you might stimulate your plants to take up more potassium by increasing their quality as well. Cultivating fungi in compost teas from your local forest can be a bit of a complex art form so you might want to try some powdered soluble colony forming units (CFUs) instead and just use the powdery spores rather than cultivating live beneficial fungus in a tea. Your organic matter seems fine, are you happy with the amount of nitrogen being cycled to your plants? This also depends on your environment. Are you happy with the form of nitrogen being cycled to your plants? If you are growing lettuce, a more basic pH is desired because a lower pH causes ammonia build up in the tissue and kills the lettuce while a higher pH favors organic nitrate cycling which assimilates much more slowly in the plant which lettuce prefers. What is your soil texture? A sandy soil supports acidity more often while a clay soil supports more basic pH loving life typically in nature. As for the pH, plants usually choose their own pH although the typical trend is usually an acidifying one where plants acidify soil (add hydrogen ions) a little bit or a lot depending on the plant. Your soil should trend towards acidity at the end of the season or else I would suspect that your organics are overriding that in particular the bacteria which make zee slime which raises the pH. Adding fungi spores will contribute to lowering the soil pH as well because they release hydrogen ions too. You can even just scoop a bunch of local forest soil into a bucket of water and distribute that over your plants, it should have plenty of local fungal spores at the very least to get things cycling the way you want.

I also have defined beds and paths in the garden.  The paths have been in arborist wood chips for the past 5 years with plenty of mushrooms and mycellium in them.