Mark Reed wrote:
From my experience, no dig is vastly superior but probably only possible on a small scale.
Oh, large-scale no-dig is already here. I think the lecture I listened to the other day was about a farm that had 13,000 acres under no-till production? Something like that. Now, whether all the new-fangled big equipment does as good as a job as what's done on a small-scale, I can't say. But they are showing significant gains in soil organic matter each year, so it's at least moving in the right direction. It just took people figuring out how to engineer farm equipment that could work with all the existing crop residue.
As far as what is taken out, nothing leaves my garden except the food we eat. I don't know if or how fast decomposition returns nutrients in a plant usable form but apparently that does happen.
Yeah. He's obviously talking to people who aren't composting their waste, and people who sell veggies or feed other people regularly. Or just the general human tendency to take more than we give back. But I'm not sure how much, if anything, we have to give back to maintain fertility in otherwise healthy soil. I've heard it repeated that there's enough fertility in one person's urine to grow all of the food they need to live. I don't remember what the supposed source for that claim was, and I'm sure it was referring to nitrogen content than a more holistic view, but who knows. But the newest research is showing that what we add back the the soil is basically worthless if the soil is healthy because we could never add as much organic matter and nutrition as a functioning rhizosphere does on its own.
Mathew Trotter wrote: The reason Joseph's plants do so well without any amendments, in my honest estimation, is because he's choosing the best plants each generation. The reason those plants are better is because they've been bred to have a more efficient relationship with the microbes that are native to his soil. ...
And also climate and practice. Those genetics keep their superior qualities in other locations for some crops and some not.
Exactly. He isn't fussing with the soil, so they adapt to the microbes that are there. If those particular microbes aren't in the new location, they flounder. But more likely, the microbes that are present in regularly cropped and otherwise unammended soil are the ones that are likely to be found in other soils across the country, though not always. The plants that have their preferred microbes in the new location do well, the ones that don't, don't.
The point is that we now know that genetics is a huge factor in determining what microbes an individual plant can associate with. GMO corn can't associated with the same microbes as non-GMO corn. Especially old varieties of corn associate with nitrogen-fixing bacteria, where most modern corns do not. It's all down to how we've twisted the genetics by breeding things in sterile soil. The plants that do best are the ones that have managed to maintain some of those associations. And the rest is basic survival of the fittest.
Mathew Trotter wrote:This is why saving seeds is really the most important part of the process. Adding Steve's mix can jump start the process of improving photosynthetic efficiency, and importing organic matter can help keep the soil microbes fed in spite of less efficient photosynthesis, and you will see the benefit no matter what seeds you put in the ground if everything else is improving, but if those seeds are adapted to the specific microbiology of the local soil that's when the real magic happens.
Yep, but as demonstrated with Joseph's dahlias sometimes the superiority of the genetics selected in one environment express themselves in other, vastly different soils and conditions.
That's not at all surprising or contrary to the point. Soils are a lot more similar than they are different in terms of microbiology. Rhizobia are found basically everywhere. Most of the beneficial microbes we know about exist in any soils that we haven't destroyed. And only something like 10% of soil microbes can even be cultured in a lab, so we basically have no clue what's going on in there.
Wish you had better access to video, because those last two lectures explain exactly why those dahlias did better for you. Joseph already bred them to maximize their possible microbial associations (at least, as far as what microbes are available in his soil.) The limiting factor was the climate and length of his growing season. Microbial activity is mediated by the root excudates released by plants, and the release of exudates is mediated by photosynthetic efficiency. A more favorable climate increases the efficiency of the whole process. Whatever the bottleneck is is what's going to slow that process down, and for Joseph, that's his climate.
And that's glossing over the fact that unsterilized seeds from healthy plants with healthy microbial associations carry endophytic and other microbes with them to their new home. Even if the desirable microbes aren't there before the seeds go in the ground, a population can eventually develop from what's transported on the seed if the conditions are favorable.
Mathew Trotter wrote:
...whereas the farmers and gardeners that have to amend their soils are importing new genetics each year that extract from the soil without giving anything back.
I have certainly amended my garden soils with years of leaves, weeds, and so on from other parts of the property. I have even mined top soil from the woods and brought it to the garden. Still I wonder about the "not giving anything back" part. It seems to imply that growing things removes stuff from the soil and that is certainly true with those people who remove and discard all the weeds and spent vegetable plants. But it you don't do that, the only part that actually leaves is the food that's eaten, doesn't the rest just get recycled? The question is how long does it take for the minerals and nutrients to return to a form that the next plants can use?
That's the other part that's answered by the latest research in that second lecture I posted (or elsewhere in the roughly 8 hours of lecture I listened to from Dr. Jones.) Adding things back to the soil is basically worthless if the soil is healthy. More biomass and fertility is created by having a diverse mix of living roots in the soil than we could ever add by putting organic matter and such on top of the soil. It does get used by microbes, and I would suspect that it even gets used by
different microbes (which might be important to the overall process), but significantly more microbes are being fed by plant exudates, and significantly more organic matter is coming in the form of plant exudates, than we could ever hope to add by placing things on the soil. That's if the soil is healthy. And optimizing soil health is down to maximizing diversity beccause a diversity of plants = a diversity of plant exudates = a diversity of microbes and interaction and breaking down nutrients into plant available forms.
The Jena experiment in Germany compared plots with between 1 and 16 different species and with 3 different levels of fertilization between nothing and conventional application rates. The plot with 16 species and no fertilization massively outperformed the monoculture with maximum fertilization. The plots with maximum diversity also survived being under water for something like 3 weeks when the adjacent river flooded, and they determined that that was down to microbial activity. And they've also figured out that plants will actively attract specific microbes to "infect" them in order to thicken their cell walls as a response to drought. And one of the farms Dr. Jones mentions was able to completely replace nitrogen fertilizer in their corn crop with an intercrop of soybeans. They weren't harvesting or tilling in those soybeans. Just having them growing in with the corn replaced the nitrogen fertilizer at a significant enough cost savings as to be preferable.
The only thing I don't know is what wins out in the end. Does the transpiration created by the extra leaf surface area outpace the drought resistance conferred by a diverse plant and microbial population? Certainly the Southwest natives found that transpiration could be fatal, hence their 5-10 plant spacing. But at that point, they were already on the path towards monocultural production, so that in itself may have compounded things. I can't say at this point. Will just have to wait and see how my various plots do.