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Too much phosphorous, red clay, not enough humus  RSS feed

 
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Hello there. I've been lurking off and on here for a few years. I just became responsible for a piece of land for which I have my first soil tests and the results are not good. There are several different gardens and hoop houses with the same problems more or less, though with varying intensity. The main issue seems to be phosphorous. My soil tests show an ideal of about 60ppm. All my gardens are 120 or above. One of my hoop houses is 876ish. Soil is slightly alkaline. Mostly red clay. Humus is .5% across the board. All nutrient levels are off the charts. I can post more detailed specs if desired.

This farm has been over populated and over worked with cows, pigs, sheep, chickens, and turkeys for years and years. My research shows phosphorous buildup is a result of all the manure. They also compost with manure and more than occasionally a dead cow or other livestock must be added. I'm trying to add more carbon to the pile moving forward. I've heard that acidity can be restored to the soil with sulfates but sulfur is already excessive everywhere I would want to lower the PH. I'm thinking of adding pine needle mulch to everything. Some say by the time they're brown there's very little acid in them but I assume the cover will only help with my lack of humus long term. I've also read that phosphorous reduces zinc and iron uptake efficiency so a foliar spray is recommended to supplement these.

My real question- What can I do long term to get rid of all this phosphorous?

How can I effectively lower PH without sulfates?

What's the best way to add to my humus in a way that doesn't put a field out of commission for a year to recover? I need to use all my space this spring but obviously some long term rehab is required.

Thank you all very much for your contributions specifically to my question and generally to the forum!
 
gardener
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Location: Cache Valley, zone 4b, Irrigated, 9" rain in badlands.
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Rather than approach this issue mechanically or chemically, what if you approached it biologically? What crops, species, or varieties are perfectly content growing in your soil exactly as it is today? I wonder if fruit bearing species like tomatoes, melons, or squash would thrive in that kind of soil?

Are your plants showing signs of phosphorous toxicity? My reading leads me to believe that phosphorous toxicity occurs at concentrations around 10,000 to 25,000 PPM, so at more than 10X the concentration reported for your highest bed.

 
pollinator
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Location: Toronto, Ontario
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Hey T.

Sounds rough, but not a unique situation, I'd imagine. I would strongly suggest that you peruse Bryant RedHawk's thread in search of super soil. I have posted it below.

https://permies.com/t/67969/quest-super-soil

I would suggest picking up christmas trees after christmas when everyone throws them away, though I was always concerned with importing unintended contaminants.

I would also suggest lots and lots of woodchips. You don't say where you're located, but many urban arborists have more woodchips than they can handle. If you can take a truckload, you might find a company that will drive out to you. In the past, they could be expected to both do that and give the chips away for free, but regional pressures vary.

I would suggest you dig those wood chips in. If you have paths, dig them down and fill them with wood chips. Use them everywhere. And start making and using the compost extracts that RedHawk describes in the thread posted above. After the first application of extract to the wood chips, I would suggest innoculating with fungal spore.

Importing non-clay clean fill is also an option, but you have to be careful of contaminants, and you didn't mention how large the land you're stewarding is, scale is a factor. But if you go the extract and fungus on wood chips route, you will attract more soil life.

How are the worms, by the way? Do you have any?

My last suggestion concerns cover cropping. It might take some looking to get strains that tolerate really rich soil well, but I would suggest cover cropping with plants that utilize or sequester the excess nutrients in your soil. Daikon radishes just for their sometimes 2' of root, just to compost in place and help drainage, maybe asparagus because it likes alkaline soils, things like squashes and melons for high phosphorous, corn for nitrogen, and peanuts for potassium. Alfalfa would also be a good choice, if it would work, as I believe they are both deeply taprooted and hosts for nitrogen-fixing bacteria. Not that you need more nitrogen now, but it would ensure those bacteria exist in your soil, and will take up the job of providing nitrogen as soon as the levels aren't so high. You are, after all, trying to achieve balance, not swing to the other end of the spectrum. Also, and I hope I am corrected if I am wrong, but I believe I remember reading that alfalfa prefers alkaline soils.

Now I might be wrong, if it is indeed so damaged by the high nutrient levels that nothing can get a toehold. In that case, I firmly believe that you need to make tiny planting pits in the ground and fill them with a mix of compost, and mineral and clay soils, and plant into those. Use a modified mounded three sisters technique. They will be your islands of change.

Oh. I guess I have another thought. You might want to think about biochar. Not in mass quantities, such as you'd need to affect drainage in heavy clay soil, but at least in quantity enough to broadcast in a crushed granular form, maybe incorporated into compost it has already been innoculating in. I am pretty sure it would greatly increase the speed of the soil remediation.

But please tell us a bit more about yourself and your land. It's more or less key to suggesting the right permacultural tool from the toolbox.

-CK
 
T Rodwell
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I've been reading through that post recently. It's an immense contribution. I've been looking for lots of wood chips to add to increase humic matter in the fields. I'm worried though, because I read that adding chunks of organic material might tie up nitrogen and O2 in the soil that I need to grow crops in the spring. I'm going to try and compost most of them this winter. I have a huge compost pile that- while it has recently had several large animals added to it, has been cooking very hot for years and has eaten whole sheep, bones and all in about 3 months. I do need to add a LOT more carbon though.

I've attached my test results which seem completely extreme based on everything i've seen anywhere on the internet. There seems to be little research I can do that leads me to any conclusion other than mulch heavily and cover crop and wait a couple years to till. This land has been extremely over tilled and has no real microbial life or worms. Tons of weeds. Small unproductive plants. Hard packed red clay aside from the hoop houses. They have historically not cover cropped.

Thank you for your time and suggestions!

             PH   P       K    HM% W/V CEC Mn Zn     Cu     Sulfur
Top         6.6 165  164 0.36 1.03 12.3 361 267   128   83
Hoop 1   7.3   851   205 0.51 0.79 32.2 455 1461  273   364
Hoop 2   7.2   876   259 0.56 0.75 30.6 424 1510  272   191
Hoop 3   7.4   749   208 0.56 0.77 35.1  501 1333  245   738
Tomato   6.7   139   184 0.36 0.96 10.9 561 250   156   77
Home L   6.6   255   323 0.6 0.94   15.2 727 438   181   233
Home R   6.2   323   296 0.6 0.93 14.3 676 575   162   280
Turk          6.8 577   305 0.71 0.76 20.9 368 1148  306   164
Lower       6.7   106   94 0.46 0.92 12.9 1371 314 158 46



 
Joseph Lofthouse
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Location: Cache Valley, zone 4b, Irrigated, 9" rain in badlands.
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As a chemist, I'd call those pH readings neutral to slightly acidic: Within the optimal range for general plant growth.  I would feel really pleased with pH readings like that in my garden.

And what a beautiful CEC. One of the benefits of growing in clay is that it sure holds onto nutrients well.

A low HM% doesn't necessarily mean that the soil is lacking in organic matter, only that the organic matter hasn't fully decomposed.

I believe that tilling is one of the best things that can be done to hard packed clay. (On large acreages where there is not enough organic matter to go around.)
soil-test-results.png
[Thumbnail for soil-test-results.png]
Soil test results
 
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Location: ALASKA
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Red clay can be a challenge to grow in because it does hold on to nutrients so well.  I'd suggest LOTS and LOTS of leaves tilled into the soil.  Red clay eats organic matter like it was candy.  It will be an ongoing process.  I could put a load of compost and/ or all my fall leaves on my red clay garden, till them in really well in the fall and by the next summer you couldn't tell they were ever there.  It took several years of additions of the organic matter to notice a difference.  I'd also suggest running your results through the Organicalc spreadsheet offered by Grow abundant gardens.  It is well worth the $20.  You input your results and it spits out organic amendments and the amounts you need to balance your soil.  That, or you can do it by hand if you have Solomons worksheets form his latest book.  Good luck!!
 
pollinator
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Chris Kott wrote:
Oh. I guess I have another thought. You might want to think about biochar. Not in mass quantities, such as you'd need to affect drainage in heavy clay soil, but at least in quantity enough to broadcast in a crushed granular form, maybe incorporated into compost it has already been innoculating in. I am pretty sure it would greatly increase the speed of the soil remediation.

-CK



Chris, this is a very intriguing idea. I am hoping Bryant RedHawk pops up and makes an input. To my thinking this seems like a fantastic idea, basically to sop up the phosphate, and hopefully incorporate it in fungal and bacterial mass rather than let it eventually leach. If a nitrogen fixer could be grown after tillage it may provide an appropriate milieu. I would be ecstatic to have a tenth of those phosphate levels. I have an area of hardpan in one field that I have been working to amend, and Joseph's

I believe that tilling is one of the best things that can be done to hard packed clay.

rings true. I am making so-so progress and it has been a good experiment, but if I had been  more pragmatic and caused a large disruption instead of waiting for purely biological remediation I think I would be far ahead.

My other interest was that given that intensive use with poultry, there may be lots of antibiotics and other residues in the soil, and absent fungi, eventually that will percolate into the groundwater. I am interested if the fungal mass available in the char might be beneficial in that regard.

The OP has not given us much specific information to work with, but it does present a general principle question.

 
gardener
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Location: Vilonia, Arkansas - Zone 7B/8A stoney, sandy loam soil pH 6.5
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hau T Rodwell  welcome to permies and thank you for your questions about your soil. This gives me an opportunity to offer you some suggestions that will work for your situation.

First off, the test results show that this land was in agricultural use and the  methods were mostly "conventional farming method".
Eveything is not so far out of whack " from the soil scientist point of view" that it can't be taken care of by just growing things in the soil and using the chop and drop (or crimp roll) method to make good improvements.

1st , make sure something is growing in the soil at all times, doesn't really matter what is growing, just that something is growing.
2nd, roll or cut the growing cover and immediately plant something else or even better plant several types of seed at the same time so that when you lay down the first "Crop" the second comes on strong.

putting some fungi slurry or just spreading mushroom fruits will improve the soil since many mushrooms will bind up P and K as well as some of your other high number elements.
by constantly having something growing and something rotting, the bacteria will flourish and also work well for the remediation of this soil.
If you do get wood chips, lay them on as thick as you can, don't worry about all the hype that you will loose N, that only happens in a minute area and it really isn't as big a concern as many people think it is.
Some tilling is a good thing, it is only when you over do it and follow that with chemical fertilizer applications that you kill the soil biota. Kola Lofthouse tills with great results for his particular lands, as an example of how tilling can be used properly.
It is important to keep observing your clay soil, there will be a point where it shows you that you can reduce or eliminate tillage all together, but I've seen people think that only No-Till is the way to build soil.
This just isn't always the case, some times turning the soil (called a disturbance) is needed to get air and open pockets for the soil microbiome to not only establish but to get it to thrive as well as water to infiltrate better.
some lands will do well with a  subsoiler as the only pull along tool for the soil, others might need a harrow plow, it depends on what your land tells you as you observe how the soil is improving.

Clovers, Daikon radish, squashes, cukes and other curcurbits, garlic, onions, all will suck up all the nutrients they need from your soil and that will help as well.
grasses and grains will also do wonders for the soil they grow in because of their deep root systems.
Most of these will grow at the same time as other items (grasses, N fixers, etc.), and help remediate your soil to a darker, richer, soil as they grow.

Nature does not work only in perfect areas of the planet, it works everywhere, regardless of conditions at the time, nature will head that area towards balance as much as possible.
Soil Science is more about Perfection according to chemistry than it is about building good soil and microbiology, only in the last 20 years has soil science even begun to start understanding the complexity of the soil as opposed to what chemistry tests tell them it needs.
pH is important but it is no more important than any other bit of what makes up soil, even plants can effect a small change in the pH of the soil surrounding their root system.

Redhawk
 
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