Podcast 344 - Keys To Building a Healthy Soil - Part 1

Excellent summary. As for the confusion about water, I refer to "rainfall" when I mean how much water a plant needs. Techniques like mulch or planting from seed reduce the needed rainfall but don't change the plant's individual needs. Similarly, I don't see anything magical coming from no-till or poly culture that changes a plant's intake. Maybe with more research

Well, since the plant receives nutrients in solution, either artificially provided nutrients (aka "fertilizer") delivered via rain or irrigation or naturally provided nutrients from adjacent (or not so adjacent, via mycelium networks) plants or soil organisms, then it's possible that a plant growing in a wel balanced polyculture will be able to get its metabolic needs met with less water when it is growing in polyculture.

If a plant has various micronutrients served up to it in delicious little bites in exchange for sugar-filled exudates, versus having to search the soil and subsoil for what it needs with just its own roots, the increased efficiency of nutrient acquisition that comes from effective polycultures could lead to equivalent growth despite diminished water intake. If the polyculture includes deep rooted plants, those plants may be able to access groundwater the crop plants are not able to access. Either of those situations could lead to "more growth with less water."

When lots of plants share a space, abundance can occur. The plants with great solar collectors concentrate on photosynthesizing, and as long as there is CO2 in the air and sunlight from the sky coming in, the total amount of biological material can just increase and increase. It seems like magic, but it's the same old magic that's been delivering abundance for eons.

Due to a miscommunication, I also wrote up a summary for this podcast. I'll share it here, in case someone finds it useful. It will be interesting to compare what two people get out of the same audio!

In this podcast, Sarah, Sean, Janet, Kai, Fred, and Paul all talk about Gabe Brown’s video about soil. It’s called “Keys to Building a Healthy Soil - Permaculture and Polyculture”

But first!! Paul wants to put in a word about hating non-native plants. For example Russian Olive is hated and some would like to make selling it (or its seeds) illegal. However, sometimes Russian Olives are about the only thing that will grow in a degraded dry place. Yes, they can become rampant in wetter areas, but the solution for that is more people on the land, to manage it. The problem is when one person is trying to manage massive areas of land. The solution tends to be mass quantities of herbicides.

On the lab, the primary invasive plant is knapweed. When they arrived, there was a lot more of it. Just recently Fred and Sarah grabbed a bunch of knapweed and used it for their “hot shower” compost pile.

The great thing about Gabe Brown’s videos is that he’s got some hard numbers and illustrative pictures. He’s got proof that what he does works.

Game is on 5000 acres and he’s doing well with no fertilizers and no pesticides and no plowing. He does have a really cool no-till drill planter that Paul thinks might be a half million dollar machine.

He shows some soil with 1.6% organic matter, some messed up soil after 17 years of tillage. This looks like dead dirt. Then he shows his soil, after years of no-till and polyculture, and it’s awesome. It’s not clear if the poor soil is from his land, or if it’s from somebody else’s land.

He went into a lot of detail about the symbiotic relationships between plants and fungi in the soil. It seems that having both plants and fungal rhizomes in the soil allows the plants to do well with less water.

The critters in the soil make all these tunnels that are helpful for everything to move around, like water, and oxygen. The bacteria in the soil make soil aggregates, and the fungi make a glue substance that helps the soil structure. When you till, you lose 30% of the organic matter in the soil.

Now Paul explains why tilling seems like a good idea, at least at first. The first time you till soil, you kill a bunch of what’s there, and you supercharge the bacteria that survive, and thus free up extra nutrients for the plants to take up. Your first season, everything looks great. It’s just that over time, you keep destroying more than is able to regenerate. Now you’ve got to add fertilizer, and synthetic fertilizers kill the fungi and other life. It’s a death spiral.

In healthy soil, the fungi (and bacteria) trade nutrient to the plants in exchange for sugar. The plants have leaves and they can photosynthesize to create carbohydrates out of CO2 - this is their currency.

There are fungi that grow inside plants - endophytes. On the lab, they’ve planted special tall fescue with ruminant-friendly endophyte inside (the most common commensal with tall fescue is toxic to ruminants). There are also lots of fungi that grow outside the plant, but right alongside. These can apparently help the plants defend themselves against diseases and pathological nematodes.

Gabe describes an experiment he did with growing corn with and without fertilizer. He’s found that when his soil is full of life, there is no need for adding fertilizer. His yields are 40% higher than average in his county. Does he have the highest yields? No, but he has the highest profits, since he doesn’t have to fertilize.

He uses cattle to help manage his land as well, he calls their manure “armor on the soil.” Paul figures his many, many earthworms are moving that manure into the soil. Gabe feels its very important to never have bare soil.

Polyculture: he started by just doing two or three species, like vetch under corn. Now he’s using many more species, so that there’s always something growing. Primary crops are things like corn or oats or sunflowers. He said that 7 was the minimum number of species, and 20 was ideal.

In the video he had lists of the species he was using. He had a different recipe for every field. Kai remembers he talked about bringing in scientists to check out a field that had never been plowed, because it was too rocky. There were 140 species (or so) in that field, grasses and legumes and broadleaf plants. He says maybe someday he’ll have a mix of over a hundred plant seeds to use on his crop fields.

Sarah points out that he talked about many different levels of plants to grow in his field, it was sort of like the layers of a food forest. Paul remembers running a combine, and how you can set the cutting blade at a particular height above the soil when you harvest. Fred remembers him describing how the “undergrowth” of an oat field has a growth explosion after the harvest. Then the field is harvested a second time by running cattle through it.

He did an experiment with mono crops versus polyculture. It’s broadly believed that the plants will compete with each other for water and nutrients, but it turned out they did a lot better all mixed together. “This whole video is worth (watching) just to see these images.”

He would say “we’re just doing what Nature does.” Polycultures are the norm, out in nature. OK, Paul points out that some plants can create monocultures of themselves. Knapweed can just about create a pure stand, because it poisons its neighbors. Douglas Fir is also good at killing its competition.

Paul recalls how he wasn’t bothered by seeing knapweed on the lab, since at least that means the ground wasn’t blanketed with persistent herbicides. There are lots of things that eat knapweed out in Russia, it’s not a problem there.

If you just wait, the predators will show up. They saw this happen down at basecamp. First they planted, then the turkeys ate everything. Then, they fenced and replanted, and then the chipmunks ate everything. That’s when the stoat arrived. This year there have been a lot of rabbits, and then the neighbor’s cats came to visit.

@Julia W: "He went into a lot of detail about the symbiotic relationships between plants and fungi in the soil. It seems that having both plants and fungal rhizomes in the soil allows the plants to do well with less water. ... The bacteria in the soil make soil aggregates, and the fungi make a glue substance that helps the soil structure. When you till, you lose 30% of the organic matter in the soil."

Just an opinion, but having read a few more topical abstracts ever since the microbial tea threads started appearing, I think these interactions represent only the tip of the iceberg. Because of where we literally stand...above ground....we are far more sensitive to appreciating what's happening on leaves, stems, trunks, etc. We see sun, rain, fog, insects, fungi, and all kinds of things interacting in the crown (above ground) of plants, but until very recently have viewed the below-ground story as roots residing in mud, water, minerals....and not much else. When I think about aggregation, I think about the concept in biochemistry of "cooperativity"...where, for example, the binding of one molecule of oxygen to hemoglobin allows the other 3 molecules to bind more easily. This is true as well in DNA strand (zipper) binding where once the first several bases of DNA bind to each other, the remaining zipper effect of forming the double-helix occurs 'cooperatively'....much easier, energetically speaking, than the initial nucleation. So I could see where the aggregation occuring below the soil is participating in a much greater amount of signalling and interaction and ...'cooperativity'... than we've previously considered.

I think you're right - the complexity is immense. It's both competitive and cooperative underground, I would guess.

Is there a good resource, website or book, to figure out what cover crops do what, when, and where?

I found this, Cornell University - Cover Crops for Vegetable Growers, but they've only got 17 species listed, not 200.

Bryan de Valdivia wrote:Is there a good resource, website or book, to figure out what cover crops do what, when, and where?

I found this, Cornell University - Cover Crops for Vegetable Growers, but they've only got 17 species listed, not 200.

This one is good...

http://www.sare.org/Learning-Center/Books/Managing-Cover-Crops-Profitably-3rd-Edition (download or view online for free)

also https://smartmix.greencoverseed.com/ create an account or just use the guest option to look at their unique cover crop seed mix builder.

Thanks James!

On the subject of plants water needs, what i heard was the amount of rainfall is more efficiently processed resulting in lower inputs over all.  Recall the segment where Gabe showed us the several plots he monocropped with ground cover (i forget the term he used) and then the plot where he polycropped and for the same rain input the polycrop growth was much greater.  I concluded from this that polyculture results in better use of available resources.  This maybe semantic,  i thought you were saying the plants need less water whereas Gabe is saying the system uses available water to much greater advantage.