After reading Steve Solomon, I am wondering if I am killing myself by eating out of hugelkultures and sheet mulches full of potassium. If the biology mechanism does not work as I outlined above, then I had better find a way to get rid of lots of logs, mulch, and manure. (All high K, and very much looked down on by Steve Solomon.)
I just wanted to clarify something. I did not mean that fungi could magically make phosphorus or any other nutrient appear out of nowhere. I meant that if the phosphorus/ potassium or phosphorus/ calcium or the calcium/ iron balance were off, the fungi would feed their plants properly regardless. Steve Solomon's big point is balance, a fairly exact balance. And according to him our sheet mulches and hugelkultures are filling the land with potassium, thus throwing off the balance with phosphorus. But I think that the fungi this woody matter encourages makes this problem irrelevant. MOST land contains SOME of the various nutrients SOMEWHERE. If it does not, you will have to import it.
He plants blocks of single species, and these blocks are far enough apart that, that they cannot 'communicate' with each other.
Under such a monoculture, an imbalance can be catastrophic to the plants within it.
However, with a well diversified polyculture, the 'communication' between various species can help overcome this imbalance.
I believe that it is this communication that makes a savannah so much more productive than a plain pasture.
The 7 layers of a food forest help assure that each species is aiding, and receiving aid from its neighbors.
I personally go with both biology and chemistry, even though people on both sides tend to say you can focus on one and the other will follow.
Mycorrhizal fungi will help plants (except brassica, beets...) with phosphorus and secondarily zinc/manganese/copper. IF you apply soluble phosphorus, this relationship will not happen.
Buckwheat cover crops (other cover crops too) will free up minerals because they supposedly exude some acid around their roots.
But what if you have say a big deficiency in boron like I do? Should I trust the biology or should I add some borax?
What if I've been harvesting from my garden every year? Wouldn't levels of say, calcium, go down gradually? Can the biology provide as much as you're taking away?
Now I plan to use corn (a warm season grass) as a mother plant throughout my garden (after inoculating it with myc. fungi)
1. All the correct minerals are in the soil in sufficient amounts, but the pH is off. There is anecdotal evidence that organic matter can allow high and low pH plants to grow side by side; probably because the accompanying fungi feed otherwise insoluble minerals to the plants.
2. Soils like my current one, which have all the right minerals, but little organic matter. Supposedly, if I add lots of high potassium logs and wood chips (or straw) I will tie up all the phosphorus, even though I have the same amount as before. But what I think it that the fungi from the rotten lots will "unbind" the preexisting phosphorus if this happens.
Of course, without the law of return, fungi or no fungi there will be problems.
Elaine Ingham tends to say that pH is determined by microbiology IIRC.
2) I think the phosphorus will free up progressively and that mycorrhizal fungi will help. That would be different fungi than the decomposers you have in your logs though.
Cover crops would help too.
Where did you read that potassium ties up phosphorus? I guess phosphorus tends to be tied up either way.
My personal plan for phosphorus (my soil test has low available phosphorus) is a combination of soft rock phosphate (aka colloidal phosphate aka Cal-phos) and mycorrhizal fungi.
Yes, I imagine that beyond a certain range of pH, soil biology will not help.
And that is one of my questions: I have a soil with plenty of phosphorus. Should I add soft rock phosphate to counterbalance the logs and chips?
According to him, hugelkultures would be a bad idea for this reason.
Here is a quote from him as well. I think he would also think that hugelkultures add too much organic matter. (He advocates using only a very small amount of compost.)
It was actually worse than he understood. Plants uptake as much potassium as there is available in the soil, and concentrate that potassium in their top growth. So when vegetation is hauled in and composted or when animal manure is imported, large quantities of potassium come along with them. As will be explained shortly, vegetation from forested regions like western Oregon is even more potassium-rich and contains less of other vital nutrients than vegetation from other areas. By covering his soil several inches thick with manure and compost every year he had totally saturated the earth with potassium. Its cation exchange capacity or in non-technical language, the soil's ability to hold other nutrients had been overwhelmed with potassium and all phosphorus, calcium, magnesium, and other nutrients had largely been washed away by rain. It was even worse than that! The nutritional quality of the vegetables grown on that superhumusy soil was very, very low and would have been far higher had he used tiny amounts of compost and, horror of all horrors, chemical fertilizer."
I conclude that organic matter is somewhat dangerous stuff whose use should be limited to the amount needed to maintain basic soil tilth and a healthy, complex soil ecology.
First you'd have to be certain you have a potassium excess. It's possible you had a deficiency to start with and have added something you need. Also it's possible that you haven't been adding as much potassium as you imagine.
If your soil has a high cation exchange capacity (usually clays do but not always), whatever amount of potassium you added might not have made much a difference.
Random idea: I wonder if growing potatoes would help reduce potassium levels.
I'm not sure where Solomon said that high potassium ties up the phosphorus. Or why phosphorus would get washed out by rain. Is it that potassium displaces cations such as calcium and magnesium and then those cations combine with phosphorus and get washed away? So you would be losing your available phosphorus and only be left with tied up phosphorus. Did I get this right?
I read a book by Gary Zimmer called "Advancing Biological Farming". A couple things form that book:
- the best way to get plant available phosphorus is to promote soil life and planting a diversity of crops including cover crops
- high potassium will interfere with the intake of calcium and magnesium
- if potassium levels are too high, apply calcium to help kick off that potassium off the clay/humus complex where it is held
In the end I wouldn't worry too much, I'm going to guess that Solomon's words are directed at a practice where people are adding compost year after year without paying attention to possible excesses they might be creating. I'd say do a soil test when you or your garden is ready and see how it fits within Solomon's guidelines.
I think the answer you seek is in cation exchange capacity. Check out the podcast I did with Helen at those on soil science. It was also a review of the dvd "agronomy in a day"
I don't think he has the whole picture though.
Are there certain circumstances, where a mineral imbalance can make plants that survive, but don't thrive. Yes. But I think they are rare in the presence of a robust highly diverse soil biology.
Or, plants that look good, but don't produce optimally nutrient dense food. Yes.n But I think they are rare in the presence of a robust highly diverse soil biology.
There are several schools of though that are very keen on balancing to get good outcomes.
At the bad end of that spectrum, there are folks who suggest that soil is just what holds the plant up. We don't need any soil biology and it just introduces risk. We'll throw in the 3 macronutrients, and 11 micronutrients and produce wonderful food from straight sand.
It might even work, but I fundamentally disagree with the premise.
I am very keen on improving soil microbial diversity through the use of more organic matter. So far, I have turned lousy neglected soil that struggled to grow runty sweet corn, and really, runty everything, into
what looks like and acts like the best soil in the county. My 2.5 secrets are compost, wood mulch, and some ag sulfur for some very alkaline spots.
Who "balances" the forest? The soil micro-herd, primarily the fugi.
Cation exchange is a good measure of the storage capacity of your soil for nutrients. Very sandy soil has lousy cation exchange numbers for example. Rain just washes out the nutrients.
The unbelievably high surface area of biochar directly adsorbs a significant amount of nutrients, and (I believe) more significantly, provides an ideal substrate for the 100s and 1000s
of species of soil life to set up shop together to trade nutrients.
Troy Rhodes wrote:By the way, if you really really like to do soil analysis and play by the numbers, adding biochar will significantly if not dramatically improve your cation exchange numbers.
Adding clay to the soil will also add CEC, but, unlike biochar, doesn't take a lot of work and putting greenhouse gasses into the atmosphere.
Adding organic matter to the soil will also add CEC, but, unlike biochar, doesn't take a lot of work and putting greenhouse gasses into the atmosphere.
In fact, if you live in a cooler climate and are thinking of adding biochar, and have wood for the biochar process, you can just stick that wood into the ground instead of going through all the work and pollution of creating biochar. Chances are that skipping the biochar process will have greater benefit for the soil. If the brown cubicle rot fungus finds that wood, the wood will last 500 years in the soil.
Biochar is excellent for soil, when done properly. And is a damn smart thing to do ..... in tropical climates.
Nothing like actual experiments!