Cover Crops in Vineyards and Orchards: Building Soil Carbon and Food Quality

0:00 Welcome back everybody. I'm looking through the participant list here and I see a lot of familiar names, people that I know have been here for the entire series. Welcome back to you folks. Probably some new names there too, and so welcome to everyone who this is your first webinar with us. And with Dr. Jones, good news is the first three are all recorded. They're available in our YouTube channel and they're already wildly popular. I know I looked last week and the first one I think already had 7,000 views and the second one which had only been out there for a week had 5,000 views. So we're definitely getting a lot of attention on YouTube with this series and I think we will continue to do so.

0:46 Tonight as Noah said wraps up the series. Dr. Jones is going to be talking about cover crops in soil health but how it fits particularly with vineyards and orchards. And I don't know Noah and Dale, you know some of the responses you get from some of our customers, I would say this is maybe one of the fastest growing areas of interest that we get calls on. We just get calls all the time from people with orchards and vineyards and they're not always huge but you know they're very high dollar acres. And so I've enjoyed working with some of those.

1:24 In fact we've had so much interest that I have designated Davis, one of our sales guys here, a sharp young man. He is going to become our orchards and vineyards expert with cover crops and in fact he's leaving Sunday to go on a week-long trip to California and he's going to be visiting a lot of our orchard and vineyard customers because the cover crops are all in all of their glory out there in California right now. So he's going to be taking some tours and learning all about that, learning how we can maybe we need to go find some new species to add additional diversity in those settings. And so I'm really looking forward to it and even if you don't have any trees or any grapevines, you know that the concepts are the same.

2:13 So what Dr. Jones is talking about here, she may be directing it specifically to these settings but the principles, so listen for the principles because those principles will work regardless of what crop that you're growing. With that I am going to shut up and go dark and turn it over to you, Christine.

2:36 Thank you very much Keith and thank you Noah and great to see so many people back on the call again today and thanks for that introduction Keith because it really leads perfectly into what I was going to say. And that is I'm just going to, we're going to have the technology is going to work. You know what Noah, I just got a sign that says host disabled participant. That's great, yeah. I just got that change, see if you can do it now. Okay, that was just amazing. You were just saying it was going to be perfect, it's going to go perfectly today. Well, now that we've just got over that little glitch, everything else is going to go perfectly. We've got all the problems out of the way right at the beginning so everything from now on is going to be perfect.

3:25 So I'm talking about cover crops for carbon capture in orchards and vineyards. And just to recap very quickly on what we have spoken about in the last three webinars, I've talked about the importance of year-long green diverse ground cover. You're probably all sick of me talking about that but I mean that's a mantra everyone has to learn off by heart. Year-long green diverse ground cover is vitally important for soil health and that all comes down to the fact that optimizing photosynthesis, so if we have green plants that are photosynthesizing, they're going to be converting carbon dioxide to liquid carbon. And that basically keeps the fungal energy channel open and we've spoken about the fungal energy channel in previous webinars and for some people that was a new term but basically the liquid carbon pathway and the fungal energy channel are the same, one and the same.

4:19 Because the carbon that's generated through photosynthesis is going to move around in the plant sap as a liquid and some of that's going to be channeled down to the roots. And when it moves out into the soil ecosystem, it's going to go out through either symbiotic fungi like mycorrhizae or we're now recognizing, and the scientists that look at what's going on in the rhizosphere and what's going on generally in the soil are recognizing that there's a lot of what we call saprotrophic fungi that are also involved in moving that energy from the plant out into the soil ecosystem or as I called it in the first webinar the soil sociobiome because it's a very social community. And we have to understand how the different components of that community actually work together. There's a lot of cooperation goes on in the soil and I think the other thing that's a little different now in terms of our understanding of what happens in the soil is that at one time it was thought to be a very competitive environment. There certainly is a lot of competition goes on too but cooperation is more important than competition in the sociobiome.

5:38 And what we have spoken about in previous webinars is how the plant-associated soil fungal networks, so as I said those plant-associated fungi may be just saprotrophs and they may be feeding on just very simple carbon compounds like sugars coming out of plant roots. And this is a different approach to what's been considered in the past where fungi have thought to be decomposers of material that's got a high carbon to nitrogen ratio like wood chips or something like that. Now there definitely are fungi that are decomposers and the kinds of fungi that you might find in a forest ecosystem, for example, if you just scrape away some of the leaf litter on the surface, will be decomposer fungi. But also in that forest ecosystem there will be mycorrhizal fungi that will be connecting all of those trees. And we're seeing that in our croplands and also in our orchards and our vineyards that mycorrhizal fungi are incredibly important. In fact in vineyards for example, grapevines are highly mycorrhizal and it's really important that we support that network there.

6:50 And as I said before, the saprotrophs, now what we've spoken about in previous days that I'm not going to repeat again except for just now is that that fungal energy channel is actually taking that energy which starts as light energy that's transformed to biochemical energy through photosynthesis and it's activating colonies of bacteria and archaea. And these bacteria and archaea are able to produce the enzymes that we need to solubilize phosphorus and also the enzymes that we need to fix atmospheric nitrogen and provided we can energize that sociobiome and keep that fungal energy channel open.

7:30 We don't need to add any phosphorus or any nitrogen. In fact, adding those things is as detrimental as I have described in the previous two webinars. So those factors that we've spoken about previously they apply not only to cropland but also to orchards and vineyards and as Keith just mentioned there's increasing amount of interest in horticultural areas in diverse ground cover. And for very good reason is because a lot of those in those situations have had bare ground up till now. But at one time flowers grew naturally everywhere and I think I've mentioned this before about the prairies being you know 500 to 700 species and probably about 90 of those species were actually flowers with about 10 of them being grasses even though we think of it as grasslands.

8:22 And this is a painting that Vincent van Gogh produced back in springtime in 1888 in France and he was just looking at the plum trees that were flowering in this orchard. It's called flowering plum trees or orchard in blossom. But look at the ground cover and I've seen so many paintings from the 1800s whether they be paintings of you know prairies in the United States or meadows in the United Kingdom or orchards in Europe that have a floral understory. In other words there were flowers everywhere. They were a natural part of the ecosystem and the ecosystem way back then functioned a lot better than it does now. And in some parts we still will see this diverse ground cover in our orchards which is great.

9:14 So just to go back to what Keith was saying about there's been a lot of interest in people using multi-species covers in their horticultural situations. Now that's because many of our current agricultural landscapes, it doesn't matter whether we talk about row crops or vegetable production or fruit nut trees vines etc and home gardens (I see this often in home gardens actually), have a lack of that diverse year-long ground cover that we need for all the things that we talked about about keeping that fungal energy channel open, about supporting the bacteria and the archaea that are able to produce enzymes that will solubilize phosphorus so that we don't have to add it. And we'll be able to produce the enzymes that can fix the atmosphere, fix atmospheric nitrogen. We talked in the previous webinar about the fact that the atmosphere is 78 nitrogen which means in non-metric terms there's something like 70 million pounds of nitrogen sitting above every acre of land. So all we really need to do is activate the microbes that are able to fix that and diverse year-long ground cover is going to be the answer to doing that.

10:27 So what happens when we do have horticultural situations whether it be vegetables or whether it be tree crops or whether it be vines or even in people's backyard vegetable gardens, if the inter-row is bare then the soil will deteriorate and this is going to have a negative impact on the health of the trees or vines or vegetables or whatever it might be. And it's also going to have a negative impact on our soil carbon because the title for today's webinar was carbon capture in vineyards and orchards. So bare soil is always going to lose carbon.

11:05 So what do we see in many of our vineyards? This is actually a photo from California. So I'm pleased to know that there's going to be more and more people planting diverse covers in the inter-rows in California vineyards but most of them have soil that's there like that and that is going to be losing carbon. If we look closely at the soil that's been ploughed up in this particular vineyard you can see that it's coming up in great big lumps like bricks, which means that it's you know severely lacking in soil structure. And again here under the trees you can see (I mean all of you who are familiar with soils will know that when the soil comes up like that it's not breaking up into small aggregates), so the points that have been made in previous seminars or webinars: the first one was basically that plant root exudates are the starting point for soil carbon. The old soil food web model was that we needed to add organic matter to soil that was going to decompose and that that would result in increases in soil carbon to some extent. That does happen but it's a very very small percentage because we were looking at that model. A lot of scientists have said it's not possible to build soil carbon because they say we add all these tons of organic matter and at the end of the day you've only increased soil carbon by a very small percentage. And that's because when it goes through that what we call the tritial soil food web, it actually breaks down, breaks down, breaks down and ends up being carbon dioxide and goes back to the atmosphere.

12:40 So if we want to build stable soil carbon, the first point is that it's going to be about plant root exudates. So we need photosynthesis and root exudation and we need to look at what are the factors that really promote that or optimize that. So they're going to be the starting point for most of our soil carbon. And in this photograph here there was straw had been laid down on the surface. This is in a vineyard which was great in a way. I mean there's lots of advantages to using a mulch. It was covering the surface and particularly in California I guess with those hot dry summers helping to keep some of the moisture in, buffering soil temperatures, all those kinds of things. Mulch is very very beneficial for soil. But on the right-hand side you can see some soil that was scraped up that was just underneath the mulch. You can actually see there's a few pieces of straw there that are kind of incorporated into the soil and there'll be microbial activity going on probably decomposer fungi because it's got a very high carbon to nitrogen ratio. And so the soil is sticking to that straw and there is a little bit of decomposition going on, there's a little bit of activity. But this soil over here on the left-hand side has been scraped up from just underneath the green leaves of these plants here. So that the root exudates (even these are weeds but even in this situation the root exudates were producing darker soil, better aggregated soil), and interestingly even though it was very hot and dry, you think well if you have plants there they'll be using soil moisture, but this soil was also a lot moister than the soil that was taken up from underneath quite a thick layer of mulch.

14:29 This is a photo that was sent to me from the south of France and I think another reason that we've tended to keep vineyards and orchards clear (in other words to have the inter-row bare) is because sometimes people would look at a photograph like that or look at a situation like that and think it looks untidy. I actually think it looks incredibly healthy and the person who sent me that photograph said.

14:53 You know his vines are amazing. He gets no pests and diseases and basically there's a whole heap of plantain there and several grasses and some other perhaps what people would call weeds. It's interesting that we always used to think of plantain or some people thought of plantain as a weed, and yet it's now regarded as very highly valuable pasture species because it has lots of secondary plant compounds that are very important for gut health in ruminant animals.

15:19 So in this kind of situation where he didn't have to plant anything, this is all just natural. But you know, you could mow it from time to time just to give you access into the orchard. It's all got there by itself. Probably doesn't have as many flowers as I'd like to see, but a very healthy situation. But for some reason in our simplistic way of thinking about things, we've thought that is unhealthy, when in fact that is healthy.

15:46 So the second point—point number one is that that kind of situation that we've just looked at is very important for building soil. The second point is that plant diversity results in increased root exudation. So we need to have some plants. Any plants are going to produce root exudates, but if we have lots of different kinds of plants, we will get increased root exudation.

16:12 So if we look at an area of land that's covered with just one thing, like say oats for example, and compare that to the same soil, the same conditions, everything the same, but we have a minimum of four functional groups in there, or probably easier to understand, just four plant families in there, the science shows that there will be increased root exudation, significantly increased root exudation, and that's what we want for building soil carbon.

16:41 So this is a lovely photo that I've used quite often. This is from the Rocky Farms in San Luis Valley in Colorado, just showing an example of different plant families. We have Asteraceae, Brassicaceae, and Boraginaceae in there. That's easy to see. But it's also great for pollinators and for also supporting predatory insects that are going to be very beneficial for the crop, and it says that pleasing as well, and it is going to build more soil carbon.

17:21 So point number one is we need root exudates. Point number two is that we need diversity to increase root exudation. And point number three is that the microbial community—in other words, what kinds of microbes we have under our plants—is actually a key factor in determining whether the soil carbon that we have accumulated there as a result of root exudates, what's going to happen to that carbon? Is it going to be respired as carbon dioxide, or is it going to be stored in a stable form in the soil?

17:57 And the microbial community in broad terms is going to be determined by the ratio of fungi to bacteria. So even though there's going to be thousands of species of microbes in there, we want it to be a fungally dominated community. And when it is fungally dominated, more of the carbon is going to be stabilized. If it's bacterially dominated, more of the carbon is going to be respired. And the key for having a fungally dominated community, again, is plant diversity.

18:34 Why would that be the key to everything? Because that's how natural ecosystems work, as I mentioned right at the beginning before I got a little bit sidetracked. You have 500 to 700 species, for example, in your prairies, as we did in our natural grasslands in Australia, and as European meadows had. And most of those were flowers. So it's those plants, those broadleaf plants, and a whole range of different species of broadleaf plants from different plant families that are going to result in a fungally dominated soil and an open fungal energy channel. And that is the key factor for having the carbon that's come into the soil as root exudates to be stored as a stable carbon.

19:25 And so they are soil building fungi. These are not our decomposer fungi. These are our soil building fungi, are supported by plant diversity. So simple equation is: more diversity, more fungi, more aggregates. And I may have shown you this photograph before—it's one of my favorites. But we just have soil particles here under high magnification. We can see the fungal hyphae pulling them together into little lumps. And when we have our aggregates, we have these beautiful pore spaces between the aggregates, which is so important for allowing the atmosphere to come into the soil.

20:02 Because if we want to have our free-living nitrogen-fixing bacteria and archaea operating in here, we want to have these spaces where we can have that atmosphere that is 78% nitrogen down in there. If you've got compacted soil, it's all very well having 70 million pounds per acre of nitrogen sitting above your land, but it's not going to be able to get into the soil unless it's aggregated. So your plant diversity is going to be very important for supporting that fungal energy channel, for supporting aggregation, and creating those pore spaces, which are important for water and a whole lot of other reasons. They're also important for our free-living nitrogen-fixing bacteria.

20:46 So just to give an example from a cover crop, this was a photograph that Ian Good in England supplied for the Phosphorus Paradox, which is an article in the Green Cover Soil Health Resource Guide, the seventh edition of that. It's just such a beautiful photograph, and then has very kindly allowed me to use it in that article and also in today's webinar. The reason I love this photograph—not only is it very aesthetically pleasing and I'm sure the bees love it as well—there hasn't been any nitrogen or any phosphorus fertilizer used for this cover. It has eight species and has six plant families. And I think one of the keys to it being so effective in building soil—the farmer that had this cover on his land reported the best wheat crop ever after this cover—and I think the six plant families is one of the keys to that.

21:45 So the other thing that we see from plant diversity in our covers is that it also increases resistance to pests and diseases, and that's going to be the main focus of my talk today. I think we all pretty much understand how carbon gets into soil, and I have talked about that before. Today I want to talk about resistance to pests and diseases. And I'm going to use another one of Engel's photographs to begin with.

22:13 This is what they call oil winter oilseed rape in England—what we would call canola in Australia. And it has four—or sorry, three. It has three companions. It has buckwheat and phacelia. Oh sorry, it has fenugreek, buckwheat, and phacelia. Yeah, okay, sorry, four companions. Did I get that right?

22:45 It's got buckwheat, veg, celia, and fenugreek. Yeah, oh that's right, there's four plant families because fenugreek and vetch are in the same plant family, and then we've got the oilseed rape, which is the brassica, so we have four plant families.

23:05 When I saw these photos Ian sent me a whole lot of photos of this oilseed rape with all these companions in it, and I said well I guess there's going to be a yield loss because of all that competition, but I suppose it's improving the soil, so over time it'll be a benefit. And he writes back and says no, there's no yield loss. These crops with these companions are actually out-yielding the monoculture canola, and it's out-yielding the monoculture canola because having all those companions in there is actually providing resistance to the cabbage flea beetle or something that is decimating monoculture crops, and it doesn't seem to matter how much insecticide you use, you can still lose a crop, as many of you will know.

23:58 So I think then we have to ask the question: How is that happening? How come when we have all this plant diversity, we have this amazing resistance to pests and diseases, and how does that look in a horticultural situation? So I'm going to use citrus greening as a case study.

24:17 Citrus greening, and Ed James—there's an article written by Dale that's in the Soil Health Resource Guide, and we were chatting about alligators just prior to this at the beginning of today's session. Maybe that's why we had so many problems with the technology, but I will mention alligators in a moment.

24:45 So citrus greening, also known as HLB, has basically devastated the nine billion dollar citrus industry in Florida, which is pretty sad, but it was a recipe for disaster that had a very long history of many pests and diseases in the citrus industry in Florida. Currently, there are around 500,000 acres of citrus monoculture, so when you look at it from the air, it's just citrus, citrus, citrus with virtually nothing else. It's very light, sandy soil. There's a lot of high analysis fertilizers used because of the fact that it is light sandy soil, although they would be unnecessary if that fungal energy channel was open. There's been cocktails of poisons used on citrus trees. In fact, if you knew what was being used on them, you probably wouldn't drink orange juice. And there is no plant diversity, so I mean it's an absolute set up for something to go wrong and lots of things have gone wrong.

25:52 But look at the inter-rows. Where is the diverse, year-long ground cover? It's not there. And if it wasn't going to be citrus greening, it would be something else. There is always going to be something that will go wrong in a situation like that.

26:08 So citrus greening, or HLB, is a bacterium that's carried by the Asian citrus psyllid, which is a little insect I'm going to show you a photograph of in a minute. And the psyllid, when it—it's a sap-sucking insect, and it's probably a bit like, say, malaria being vectored by a mosquito. Although malaria is not a bacterium, it's a parasite, but the mosquito will bite somebody who has malaria and then go and bite somebody else and carry the malaria from one person to the other. So when the Asian citrus psyllid sucks the sap from a citrus tree and goes and sucks the sap from another citrus tree, it's going to carry the bacterium from one tree to the other, and so it has spread through the entire citrus industry in Florida, and it causes tree decline and eventually death of the trees.

27:23 This is our little sap-sucking psyllid, our Asian citrus psyllid. It's quite a cute little thing actually. And this is what citrus greening looks like. So the leaves go kind of yellow and crinkly, and because the tree gets all blocked up—the phloem gets blocked up—it's not functioning effectively. It can't actually get sugars to the oranges, so the oranges just stay green and they never ripen. And you can't sell green oranges, so there's been millions of dollars spent on various treatments trying to overcome this problem.

28:10 Worryingly, one of those was to use an antibiotic because it was a bacterium. It was considered, well, maybe we could use an antibiotic. It was a human-grade antibiotic, oxytetracycline, was applied to over 480,000 acres of citrus trees in 2016. That didn't work, so it was reapplied in 2017 and 2018, and the EPA approved that. EPA is supposed to stand for Environmental Protection Agency. How a human-grade antibiotic could be approved for use over 480,000 acres you would have to wonder, especially when we have all this talk about antibiotic resistance.

28:49 Trees have also been injected with insecticide, and that hasn't worked, and genetic engineering is the latest thing that scientists are talking about—will genetically engineer a citrus tree that is immune to this bacterium. Well, all of these treatments, including the genetic engineering, have actually failed to control HLB, and around 100 percent of the trees are now infected, and the multi-billion dollar Florida citrus industry has been devastated. And I was looking last night at just reading some articles on the internet, and even the latest information is still saying that there is no cure.

29:34 But the problem is not the lack of chemicals. The problem is lack of plant diversity. And thankfully, our hero in this story is Ed James, who has been demonstrating that plant diversity can reverse citrus greening. And Ed came across that discovery by accident, as so happens with many of the discoveries that people make. And you can read more about that in the Soil Health Resource Guide. There's an alligator in the story as well. I'm not going to say any more about the alligator. You'll have to read it to find out where the Florida alligator comes in.

30:12 But this is our hero, Ed, and he's holding a sun hemp plant there upside down so you can see his orange trees in the background here, and this fantastic cover crop that he has in the inter-row. And again, you can get more information about how Ed manages these diverse cover crops, but he basically plants several in one year, so they're all annual. So he'll plant one, it'll come to maturity like this, and then he'll roll it or flail mow it. He'll flail mow it, and a lot of it gets pushed in under the tree so that it's actually mulch under the trees as well, and then plant another crop over the top.

30:57 Of that so he's continuously keeping photosynthesis going and there's continuous supply of root exudates and then of course you also do have the organic matter that's coming from just from the plant material as well.

31:14 So what has been discovered in this situation is that when we have reintroduced diversity to this plant community, the really interesting thing about Ed's trees is that they are now productive but they're still infected with HLB. That's the thing that I find fascinating. So the bacteria is still there, the sap sucking Asian psyllid, Asian citrus psyllids are still there. We're not killing the pest, we're not directly trying to kill the bacteria. We're just dealing with the problem with plant diversity and the trees are still infected but they're productive. That is key to this story.

32:04 Now there's been quite a few scientists have become interested in what is actually going on when we have diverse understories in orchards and they have found that plant diversity supports soil microbially, soil microbial diversity. Surprise, surprise, and that improves soil health. So there's some nice research articles available now. So we have our trees here and then in the inter-row we have our diversity of plants in the cover crop and the scientists are finding, surprise surprise, that the roots are intermingled and that there's increased microbial abundance, there's increased microbial diversity. That's all been measured but it couldn't possibly not happen and they're finding that there's increased nitrogen, there's increased carbon in this system and there's increased phosphorus, increased cycling of phosphorus. So all the same things that we see when we use a diverse cover crop in our arable land, we are seeing the same things in vineyards and in orchards. That it works the same way and now there's we're getting some science around that. The title of this article is 'The Impact of Cover Crops on the Soil Microbiome of Tree Crops.'

33:33 Great. So time and again it doesn't matter whether we're talking about a walnut grove in California or a vineyard in California or a citrus grove in Florida, we're seeing that diverse plant communities exhibit far greater resilience to stress like say drought stress for example and far greater resistance to pests and diseases. So the question then is, well how exactly, how does that work?

34:04 Okay, we have more microbes there and we have more microbial diversity if we have diverse ground cover. But so what, how can just because we have more microbes in the soil and just because we have more microbial diversity, how can that make a tree that still has a bacterium in it that for most trees is actually causing the death of that tree, now suddenly that tree can be productive? Same tree, still got the same issue but now all of a sudden it's productive instead of dying.

34:43 The answer to that is that all plants, including the plants that we have put into the inter-row and our grapevines or our citrus trees or our walnut trees or whatever it may be, all plants are multi-story microbe apartments. In other words, there are more microbial cells within plants than there are plant cells. So if we look at plant leaves or plant stems or plant roots under high magnification, we will see that they are full of microbial cells. And those of you who saw James White's presentation on the Riser Pagey cycle will see that he shows some fantastic photographs, really like high magnification photographs of plant cells with all these little bacteria moving around in them. And it's not just bacteria that we're going to find in plants. We're also going to find algae and fungi, plant associated fungi and plant associated bacteria and archaea. And that's a great thing because these microbes are capable of performing many amazing tasks, including protecting our plants from pests and diseases.

36:00 So we've talked in previous times about the rhizosphere, which is the area around plant roots. We've talked about the phyllosphere, which is the area around plant leaves. And maybe you know there's things that you could apply as foliar like fish hydrolysate. Just while I'm mentioning that, I've had heaps of emails from people saying that they applied fish hydrolysate in strips to see what would happen and the strip greened up very quickly and Brix tests showed that the Brix refractometer showed that the Brix levels were much higher. So there's been lots of audience satisfaction, if you like, about using fish hydrolysate. So we've so that's the philosophy. So the endosphere is what is inside the plant and bacteria and archaea and fungi that live inside plants we call them endophytes.

36:52 But the endophytes come from two places. One is the core microbiome, which is the microbes that are in the seed of the plant. And we did mention the core microbiome in previous webinars and the important thing about that is that research is now showing that some of our modern day varieties of crops, for example, don't have the same core microbiome. They don't have as many different kinds of microbes or abundance of microbes in the seeds as older varieties. And my understanding of that is that it's not so much the variety that's the problem, it's the fact that those plants have been bred and selected under high fertilizer conditions. So we've used lots of nitrogen, lots of phosphorus and the plants are no longer communicating with the soil microbes, no longer taking up endophytes or no longer taking up microbes from the soil and supporting them as endophytes within the plant so they can't get into the seed.

38:01 So what we need to have happening in the soil if we want to have a good core microbiome for our seeds, so that we will have healthy plants, is we need to have biological induction taking place in the soil. You won't probably find that on a Google search because it's my term. But the core microbiome of the seed is dependent on the species, is dependent on the cultivar. As I said, some modern cultivars of commonly grown crops like corn and wheat and those kinds of things have very dysfunctional core microbiomes, whereas older cultivars have better ones. And it's a specific assembly of bacteria and archaea. There's protists in there as well and fungi. So the microbes that are in that seed form a relationship with newly germinating plants. So we put the seed into the soil, we apply moisture or grains or something and the seed imbibes that moisture. A whole lot of enzymatic processes take place within the soil, within the seed and it starts to germinate. And that is when the seed starts to communicate with the microbes around it, the microbes within it. And if it has a good core microbiome, it will form a relationship.

39:30 Well, if it has a healthy microbiome, those microbes will actually emerge from the seed as it is germinating and enable that seed to obtain many of the nutrients that it needs. They will also communicate with free living microbes, and if the plant needs more microbes, it will take those microbes up, internalize them as James White would say, and they will remain in the plant for the duration of the plant's life.

40:04 So let's just look at this from the point of view of a citrus tree, for example. So it has HLB, it's dying. There are bare inter-rows, there is no microbial diversity for that plant to call on to help it. And plants will call for help—they will send out signals through the roots and look for microbes that can help them. But if those microbes aren't there because we don't have the plant diversity there, then they call for help and their call is not answered.

40:39 Now we have a diverse cover in the inter-row. We have lots of different kinds of plants growing there from different plant families, lots of different kinds of microbes there, and they're all connected as that photo showed, that diagram showed before. We've got the tree roots coming in under the inter-row and they're going to be mingling with the roots of our cover crops. And so when those trees actually send out a signal from their roots to call for help, there are microbes that are going to be associated with our cover crop that are able to help them and they can be internalized through this process of biological induction that can be taken up into that plant. And those microbes will help the plant deal with that bacterial infection.

41:30 So those free living microbes that can be internalized by plants are also significant for nitrogen fixing. They can live within the plant, be supported by the plant, and fix nitrogen. So you don't have to have nodules on plants to fix nitrogen. Every plant is able to support endophytes that it takes up from the soil, and important for plant protection, as I just mentioned with the diseases, and important for plant fitness for all of those reasons. But as I just mentioned, plants can't internalize those microbes if they're not there in the first place.

42:07 And so how do we create a soil environment with a wide diversity of microbes? Well, you know the answer to that—we have to have a wide diversity of plants. I think it's a no-brainer, really. But I guess the thing is that until recently we actually didn't know why diversity worked, why it was that a diverse cover crop, for example, in the inter-row is going to be more effective than just a cover crop of one thing, say a cover crop of mustard or a cover crop of oats or something like that. It's not going to give you as much benefit as having your four plant families or a minimum of four plant families there.

42:48 So plant diversity, as well as having ground cover and as well as having photosynthesis and as well as having something green, plant diversity is going to significantly stimulate biological induction. In other words, plant diversity is going to stimulate soil building. It's going to stimulate nitrogen fixing. It's going to stimulate solubilization of phosphorus. It's going to stimulate the uptake of trace elements, minerals and trace elements, you know, other things like calcium, magnesium and sulfur, boron, cobalt, lithium, and all those things that plant needs. And it's also going to stimulate biological induction, which is the taking up of what were free living soil microbes, which now become endophytes. And only if the plant needs them—it's not going to take those things out. Your plant that's perfectly healthy, it's not going to take microbes from the soil that it needs to help it fight disease because it's not in a situation where it needs them. So these diverse systems are self-organizing. The microbes know what to do. The plants know what to do. We just have to create an environment where all of that can happen. We don't even really need to know how it happens. So if we have above-ground diversity, we will have below-ground diversity, and all the details will take care of themselves.

44:14 There's plenty of science around it now. If anyone wants to read, I mean, obviously if you read articles about the holobion, if you read about vertical transmission—vertical transmission is just the core microbiome and how that's inherited from one generation to the other—all those kinds of things, all those kinds of keywords are going to find you lots of articles. If for some reason, you know, Noah would like me to give you some articles to look at, we can attach them to the YouTube video.

44:42 But really, if you get the diversity there and get you along green, so we know in an orchard or a vineyard situation, as if James has done, you may just have to have a series of annual covers that you just keep—you grow them, you terminate them in some way, you grow them again, you terminate in some way, you grow them. And there's going to be lots and lots of approaches to that. Some people might even turn them in mechanically because they don't particularly want to use something like glyphosate, or they might roll them, flail mow them. I mean, there are so many different approaches to this. And obviously, depending on which part of the world you are and what time of year it is, it's going to be different species. But remember that you want to have diversity in that mix.

45:28 So just to summarize, plant diversity is going to restore topsoil through building soil carbon, and that's going to produce aggregation and give us good structure, which is going to be so important for air and water and getting nitrogen, oxygen, all those things into the soil. It is going to completely replace fertilizer unless, as I said, and I have said in previous webinars, you do need to do leaf tests or tissue tests just to make sure that there isn't some essential trace element that's missing. And by all means, if something is not showing up in a leaf test, then do apply it. Most of them can be applied as foliage. Some of them will need to be soil applied, but mostly a foliar is going to be more effective and cheaper for you to do that.

46:25 Insecticides become obsolete. And I think I've said that before—there are farmers who have not used an insecticide for 10 or 15 years. If you have insect pests, it's a symptom of low diversity. Again, if you have fungal pests, it's a symptom of low diversity, so fungicide becomes redundant. Definitely will support beneficial insects. Displaces weeds—if we have a very vigorous ground cover of lots of different kinds of plants, our weeds become irrelevant largely. And it improves landscape function. And what I mean by landscape function is basically how water moves through the landscape, so there's going to be droughts become less severe, floods.

47:08 Become less severe. The whole water cycle functions much more effectively and this could apply even to your little backyard home garden. Doesn't even necessarily have to be a big vineyard or a big orchard. You can grow your vegetables in mixes. Interestingly, this sweeter listen here is in the brassicaceae family. It's a brassica. Many people don't realize that, but all these things are edible as well. You can eat the flowers, everything in the asteraceae family. Might use some of them are bitter and I don't think I've ever tasted a daisy yet that I really particularly would have included in a salad, but they look pretty. Lettuces are in asteraceae where we've got your alliums. You know, so just get a mix. It's visually appealing. There's going to be lots of valuable vitamins and minerals here for people as well. And it's great for soil building. You'll build more soil with plant diversity than you will just with a monoculture or something.

48:10 Even just in your home gardens, just even if it's not something you're going to eat, look after your trees by having a whole range of different kinds of flowers under trees. Trees and grasses do not get along. This tree is going to be much much healthier with a diversity of flowers underneath it than it would be if it had grass underneath it. And look after our pollinators.

48:35 And there was this one more slider I was going to show you and that was this one of a refractometer. I've just had so many questions about how do you measure brix and what's a refractometer, where do I get one. Just look it up on the net and you'll find you know how to measure brix and there'll be tables of different brix levels and everything. But basically you're going to squeeze some sap out of the leaves of your plant using a garlic press or something. You're going to put that on this plate here, put the slide cover down and you're going to look through it and it's just going to measure the refractive index of the sap. This is just to see how much light is refracted as it moves through that sap. And you want to have a really high refractive index. In other words, a high brix level. Because if there's lots of solid material in that in the sap, though that material is going to be sugars, it's going to be minerals, it's going to be trace elements. It's going to mean that the plant is nutrient dense and it's going to be much better for human consumption or animal consumption. And it's also going to have much higher resistance to pests and diseases.

49:53 So you're using a spade to do the hole, have a look to see whether you have aggregates forming. Have a look to see whether you have riser cheese on the roots of your plants and use a refractometer to measure brix levels. Just to give you an idea, like even if you were trying different things, I mean there's been a lot of discussion about biostimulants and biological inoculants and there's a whole range of things that people can use. But you know, fish hydrolysate is something that I have mentioned several times because it's one way of transitioning off inorganic nitrogen as well because it's an organic nitrogen source. But a few people who have tried it and emailed me back have said that one thing they really noticed, in addition to the fact that their plants were greener, was that their brix levels went up. But you'll also see higher brix levels when you have diverse plant diversity. Plant diversity will also give you higher brix levels.

50:51 So I'm just going to stop sharing there, Noah. We actually got to the end and we still got a little bit of time. What have we got? Still got half an hour, I think, is that right?

51:04 It was perfect. Yep. Well, not perfect in that regard, but we made it through the information. And like I said, that's all that people really care about anyway. They don't care to look at my face, that's for sure. So we are going to kick things off here with the questions. And we've got quite a few already in here. So I'm already kind of thinking we're not going to get all of them this evening, but I do have a question here from Claire. She said, what are your thoughts on fungal diseases in orchards and vineyards, like mildews, cankers, et cetera? And Claire, I guess I'm looking for more insight on what you mean by like your thoughts. Is that just something where you're trying to treat those? Or I've read a couple questions that are kind of along those same lines of what to do with those fungal diseases.

52:06 So when I was reading up about the citrus greening last night, no, one of the things I noticed was the citrus industry in Florida has been plagued by diseases since you know, 1960 or something. There's been a whole range of different diseases. Citrus greening has probably been the worst one because it has totally devastated the industry. But one of the other things that did come up was there were a lot of what they call cankers, like different canker things that were affecting the trees. And again, I would just put it back to the fact that there was just citrus, like just a monoculture of citrus with no plant diversity. You don't have year-long green, diverse ground cover. We've had the same issues in our citrus orchards in Australia. We haven't had the citrus greening issue, but we've had lots and lots and lots of issues, not just with diseases but also with insect pests like strips and things like that. And they've all been cured by diverse ground cover. I know it sounds too simple. But and the other thing is if you're in a really humid environment, for example, and there are issues with you know like fungal pathogens on the leaves, then that's often where something like a compost extract or a vermi liquid sprayed onto leaves can have a huge effect because you're just basically changing the microbial balance on the leaves.

53:37 And that also works on grapes or it also works on you know plants that are in the squash family like pumpkins and zucchinis and things like that. You'll often notice mildew on the leaves of those when just getting towards the end of summer coming into fall. That as the photosynthetic rate of the plants drop and the plant's immune system is not so effective, you'll start to see mildew on those leaves. What I find is really effective in my garden at home, when I start to see that happening, is I just spray milk on the leaves because that just supports a really healthy microbiome on the leaf surface. And those microbes that grow in the milk—I guess probably lactobacillus—are able to combat the mildew provided.

1:01:31 Carbonate. So theoretically, the parent material is calcium carbonate. They've been derived from limestone. They have massive amounts of calcium in them, but when you do a soil test it will show there's virtually none available, and it's not available because the sources are not biologically active. And so the soil test is really misleading in fact. Calcium is the fourth most common element in soil after silicon, aluminum and iron. It's the fourth most common element in just about every soil in the world, and yet how many people come back saying that they're deficient in calcium. So it's a bit like phosphorus. An available phosphorus test will tell you that your soils are low in phosphorus and that you need to apply it, but a total phosphorus test will tell you you have thousands of pounds of phosphorus, and all you need to do is activate it.

1:02:33 Have I confused you totally? A soil test is useful if you actually understand what it is that you need to know. You need to know something about why are you taking a soil test and what are you looking at. You really need to look at your totals and you need to understand what they mean. Unfortunately soil tests in the past have just looked at availables, looked at available nitrogen and looked at available phosphorus. They've only been very shallow, only been like the top couple of inches of the soil. And the recommendation that will come back from the lab is you don't have enough nitrogen, you don't have enough phosphorus, you need to add it. And soil tests traditionally have been taken as the basis for a fertilizer recommendation. And the recommendation that's invariably come back is that you need to add something.

1:03:18 So if we look at soil tests in a different way and say well, we actually do want to know what's in our soil. We want to know what our total phosphorus is. We want to know what our total nitrogen is. We want to know what our total calcium is, just so that we're reassured that those things are actually there. And then we should probably do a leaf test just to make sure that the trace elements are getting into our plants. So yes, they can be valuable. I wouldn't write them off completely, but they have been very misleading in the past, and they've probably been the reason that people have applied so much nitrogen and so much phosphorus to soils because a soil tester says there's not very much available. And farmers have thought, for example with phosphorus, if it's only showing there's a few parts per million of phosphorus on a soil test, farmers have mistakenly believed that that's all they had. Or they've mistakenly believed that what's gone out the farm gate in product has depleted the amount of phosphorus that's in their soil. It's like saying if you take nitrogen out of the air that you're depleting the amount that's there, or if you take salt out of the sea that you're depleting the amount that's there, because you can't deplete it. It would take thousands and thousands of years to deplete it.

1:04:42 Okay. Raul asks, kind of more of your opinion here, so if you don't want to share that's fine. But your opinion that microbes are living chemicals, it's something that I know I've heard maybe only once or twice before. And then the possibility that the archaea bacteria has the capacity to degrade single-use plastics. Well, every living thing is made of chemicals. I mean we're made of chemicals too. So I'm not really sure what he's referring to. I obviously haven't read the same article or I'm not aware of that research. In terms of degrading complex structures like plastics, bacteria and archaea have amazing capabilities to do that. I wouldn't be the least bit surprised that they can degrade plastics. I mean they're often used to clean up contamination. Now if there's been an oil spill or something like that, bacteria are fantastic for cleaning up those sorts of things.

1:05:46 Wouldn't surprise me. And you find bacteria and archaea in very, very inhospitable environments, you know like under the ocean. There's what they call these deep ocean vents that have magma spewing up out of the earth, thousands of degrees or something. And you'll actually find bacteria and archaea living in those very, very hostile environments. They seem to be able to live almost anywhere. And at one point, archaea were considered to be some specialized kind of bacteria that was able to withstand very extremes. I think they were called extremophiles, because that's where archaea were first isolated in these very extreme environments. But then we discovered that actually archaea are very common. We just didn't have the way to have the technology for assessing archaea at one stage. Now we find that the human gut has hundreds of species of archaea. A rumen of a cow has hundreds of species of archaea. There's hundreds of species back here in our soils. They're very, very common, but at one time they were considered to be extremely rare.

1:06:57 So I mean, and there are some microbes that live in the soil that don't utilize light energy. In other words, they're not living on that fungal energy channel. They're not using root exudates for energy. There are microbes in the soil that can be called autotrophs, and they're the ones that are able to photosynthesize themselves like blue-green algae, cyanobacteria. They can photosynthesize. They don't have to depend on a plant. And then there's the heterotrophs, which are the ones that do depend on plants or they do depend on decomposing organic matter. And then there's the chemotrophs. You know, there are bacteria that can live on sulfur or something, and they're just going to change its oxidation state and use the energy that comes from reducing or oxidizing a chemical. So they're called chemotrophs. So yeah, it can get very complex, but all microbes are going to be composed of chemicals. So I'm not really sure, as all living things are going to be composed of chemicals.

1:08:06 Okay, I'm reading a question on Facebook here. Is it safe to say that having green plants in the inter-row will increase soil moisture, or is there a risk of drying out the soil with certain cover crops? So in the short term, it's quite possible, I suppose, that if you have a really dysfunctional soil and you add extra plants in there, obviously they're going to photosynthesize and you use some moisture that's there. But what happens is that as they build soil, once they actually get those aggregates forming, and it doesn't really take that long, if you have a diversity of plants and you don't put high analysis fertilizer on them, it doesn't take long. They're going to form root sheets. They're going to start aggregating the soil. And once they actually form those aggregates, soil moisture that's...

1:08:56 Inside an aggregate is going to be protected from evaporation. So very rapidly you can change the whole water balance equation of the soil so that it holds more moisture because when you look at water balance, like how much water comes into the environment, how much goes out and how does it go out, how does it actually leave the soil? Does it leave by evaporation or does it leave by transpiration? And in actual fact in most environments, particularly somewhere like California for example, in summertime most of it is going to leave as evaporation.

1:09:30 And that's where people get really confused because in the past evaporation and transpiration have been put into one term called evapotranspiration and we've assumed that when you've got green plants there that they're using up all the water in transpiration. In actual fact when you have bare ground you lose more as evaporation. So by having green plants there yes they will transfer some moisture, but if they're diverse and if you haven't used high analysis fertilizer they are going to very rapidly build riser sheets and aggregates and that any water that's been added to that system is going to be held within those structures and they're going to conserve moisture.

1:10:16 So you can change the whole water balance equation and we've frequently seen in orchard and vineyard situations in Australia for example, especially where people are using irrigation water so that they've had to pay for it. In our situation people have to pay a lot for water. They've been able to increase their water use efficiency. In other words they've been able to reduce the amount of water that they've needed to use by something like 40 percent, which saves them a lot of money.

1:10:45 And I think Brendan Rocky also says the same thing, that the reason that his potato production in Colorado has become more profitable is because he's now using diverse covers rotated with his potatoes and the covers are building the soil and he uses less water. So his water use efficiencies are where he's actually saving the money. So don't confuse transpiration with evaporation.

1:11:12 The other thing about water that's transpired is depending on the environmental conditions, obviously on a windy day this is not going to happen, but under many conditions we have what's called a short water cycle where water will be transpired and then overnight will return back to the soil as dew or as fog or something like that. And time again I've been told by farmers in Western Australia, which is very light soils, very hot dry environment low rainfall, that where people have planted perennials, perennial pastures, and they'll often just plant a small area to start with like 20 hectares which is like say 50 acres or something, but this will be on a big ranch so they'll have thousands of hectares and 50 acres will be a small area compared to the rest of it.

1:12:07 And they'll plant like just a square of perennial grasses. Now they're putting more things in besides the grasses but originally it was just like several species of perennial grass and they say first thing in the morning, just as the sun was coming up you go out and look and there would be a square of fog, you know what I mean, like mist just sitting just like a perfect square sitting directly above those plants and nowhere else. And then when you went and looked at the grasses the leaves were all wet. So in other words what's happening is it's creating its own micro environment and a lot of that moisture is actually returning back to the plant. So yes they did transpire it but it's a short what we call a short water cycle. It can return back as dew or fog.

1:12:52 And that's the sort of thing that people don't take into account. If you've got bare soil it is going to lose moisture. It is going to go downhill and lose aggregation. It's becoming more and more blocky in structure. It's going to become more and more compacted. So even when it does rain or even when you do irrigate, moisture can't even get in there.

1:13:10 So when you look at the complete water balance equation infiltration is going to be the first thing and if you haven't got aggregated soil how can the water infiltrate? And then you need it to be, you need to have the kind of soil structure where it can be stored and be protected from evaporation. The other thing about having a diverse cover there is that if you've got deep roots under those plants or any kind of roots really compared to having bare ground with no roots in it, the water will follow those root channels down. So when you do irrigate or when it does rain the water is going to penetrate much more deeply into those soils. So even being deeper in the soil profile is going to protect it from evaporation.

1:13:53 You really just want to change the logistics of the whole thing so that more infiltrates, less evaporates and anything that transpires is actually going to make you money. Transpiration makes money. Evaporation loses money. So it's I don't know when people go, oh if we put cover crop, if we have a cover in the interior it's going to use water, it's really not based on science. It's just a human belief that that's what's going to happen.

1:14:28 Okay so Shorty says when I'm seeding a multi-species cover crop I want to use a vermi liquid on the seed. How long after that vermi-liquid is applied will the auto-inducers in the vermi-liquid be effective? Okay so that's a great question. I wasn't sure whether to talk about biostimulants today or not and I thought we'll get really bogged down in biostimulants so I didn't mention them because how many emails have I had about biostimulants? Hundreds of them. So it's a great question Shorty.

1:14:58 So the thing is that biostimulants, if it's vermi liquid that we're talking about, we're talking about the chemical signaling molecules that microbes use to communicate with each other and these are called auto-inducers. Now if you look at the structure of an auto-inducer and I did think about putting some pictures in my presentation, I decided not to, but they're all based on what's called a carbon ring. In other words there are six carbon atoms. It's called a benzene ring. I don't know why we call it a ring when it's actually a hexagon, but there's six carbon atoms forming a hexagon and then there's other side chains coming off that. But all auto-inducers actually have that basic what we call a ring structure which is very stable.

1:15:45 So once these signaling molecules that bacteria and archaea and fungi, all living things actually produce to signal to each other, are very stable molecules. But because they need to survive in that sociobiome, they need to go from one microbe to another and another one needs to be able to recognize that signal, so if it was broken down easily it's not going to be transmitted. But it can be broken down by microbial activity. So the question Shorty asked was if I put auto-inducers from vermi liquid for example.

1:16:21 Onto the seed, how long will they last? Well, the answer is that if it was dry, if you had some way of drying the seed, they're probably going to last for I don't know, six to eight weeks maybe. But if the seed is still wet, which means that microbial activity can take place, they're not going to last very long at all, and you need to get that seed straight into the ground.

1:16:43 In some situations where people are planting dry, what we call planting dry in Australia, so that if we're in an environment where we don't get very frequent rain, sometimes farmers will plant a crop dry and just have it in place waiting for it to rain, and so the soil will be dry. You'll be putting auto induces on the seed and then putting the seed into dry soil, so the seed isn't going to germinate until it rains. In that situation, it can sit there for six weeks and still be effective. So you could let's say you could plant for a whole six weeks up to when it rained, and the seed that you put in the ground the day before it rained is going to grow just as well as seed that you put in the ground six weeks before. That's what we're seeing. But if the soil was wet or if the seed was wet, then you're going to have microbial activity and it is going to break down, decompose those auto induces.

1:17:46 So the salient point is: if it's dry or if there's no microbial activity, it will last for several weeks. If there is microbial activity, it's not going to last very long at all. And the other thing is you don't want to have wet seed lying around because it's going to get moldy. So if you have some way of drying it, that's fine. If you can't dry it, you actually need to plant it the day that you apply the auto induces.

1:18:15 I'm going to ask this question kind of selfishly because there's a plug here. Willie asks, what are your thoughts on the chaos garden cropping for vegetables, where all the different summer veggies are planted in a mix, hence the word chaos? Have you done any kind of research, any studies on the milpa program, anything like that?

1:18:38 No, I haven't done any studies on it, no, but I think it's fantastic. I really, really love that whole idea of the milpa gardens, and I love the community involvement aspect of it as well, and I promote milpa gardens to everybody I talk to. Even though in other countries we haven't got access to your milpa seed mix, just saying, you know, look, just get a whole lot of vegetables, a whole lot of flowers, throw them in together. It's probably your harvest efficiency, if you like, your harvest index, is not going to be all that high because it's going to be a lot of wastage in there, well, what we would think of as wastage in terms of vegetables, because not everything that's going to get picked and not everything is going to get used. But there has been no time involved in cultivating soil, applying any fertilizers, weeding, and I think there's huge advantages. I would really like to see much wider use of that technique in commercial vegetable production. I don't really see why.

1:19:41 I mean, as gay brown has done in the past, you can just come in and graze the whole thing after it's been, you know, you've picked your vegetables out of it, and you get really high live weight gains in livestock because there's so much diversity, there's so much nutrition there, especially if you put herbs and things in the mix. I mean, I can't see any downsides to it at all. I think it's a great technique. I'd love to see it adopted much more widely. Really, I guess the problem is that most people who grow vegetables commercially have, you know, half an acre or something like that, and so they would see that it's not an effective use of their land. But maybe if we just moved a little bit further away from urban areas and we converted some, you know, like where milpa gardens have been used on ranches and things like that, it's not such a big issue. Like, what's a couple of acres, really? Throw in a milpa garden and it's going to build beautiful soil. It's going to be great for predatory insects. It's going to be great for pollinators. It's going to be great for the local community. So yeah, I give milpa gardens 20 out of 10.

1:20:56 So if that's something you're interested in, on our website, if you just search milpa, or you can even go to milpagarden.com. What we're referring to is our milpa mix. We have 40 different vegetable species in there, and we're willing to donate up to an acre's worth of seed if you are willing to donate up to 75 percent of the produce. So kind of a cool project. It's not like we're the only ones that are mixing vegetables together, but we're really trying to promote that in building communities because that's kind of what food should be about. So if that's something you're interested, you can visit our website there.

1:21:39 I will wrap this up here with one, possibly maybe two questions. Eric says, do you know if a strip of plant diversity can have an effect on the culture on the side of it? And so I'm going to kind of add to that: have you seen any effect on diversity next to a monoculture? How far of an effect does that have?

1:21:59 Well, that would depend on how extensive the root systems were of the different plants. What has been shown with citrus orchards, for example, is because the trees actually have roots that run right in under the inter row, when you plant a cover crop on top of that, the roots are able to mingle. So I would say that the effect will only last as far as either the roots can mingle or the mycorrhizal networks can extend.

1:22:29 Yeah, so there's, it's probably in an annual crop, it's probably not going to be very far. You probably, like with something like relay cropping or inter-seeding or inter-cropping, you're definitely going to get that effect because you've got everything, you know, that it will extend, you know, 12 inches or so, or maybe even further if it's mycorrhizal. It'll probably extend a little bit further than that, but it's not going to extend for 10, 20 feet or so, because there's no way the roots either have to be in very close proximity or they need to have good mycorrhizal networks like bringing them into contact with each other. And the problem is that in an annual situation, plants are not really there long enough to form those really large mycorrhizal networks.

1:23:27 In an orchard situation or in a vineyard, you should have, provided you're not using too many toxic chemicals, you should have a really good underlying common mycorrhizal network that your inter-seeded or your inter-row cover crop can just plug into, just plug straight into like the grid, really, the grid that's already there.

1:23:53 You're not going to have that in an annual crop, so it is going to be a little bit different in an annual crop where things are only active for a couple of months. They're not going to be good microbial networks under there if that answers the question.

1:24:12 There can be good mycorrhizal networks in a high diversity cover crop within that crop itself, which is why we're seeing those great features like drought tolerance and everything, but it's not going to extend very far beyond that. That's what I'm saying because the plants aren't there for very long.

1:24:30 So this last question, it's somewhat off topic but I think it wraps up this series in a sense of why this all matters. Because, you know, we love plants but at the end of the day the reason we're trying to do this is for human health. Tatiana says, do you think that we as humans when healthy recruit particular types of microbes into our bodies through chemical signaling? So what kind of benefits is there for us in our food system through healthy soil?

1:25:08 That's an interesting question. We obviously need healthy soil to have nutrient dense food. But when we're looking at this from the human perspective, we also need to eat a wide diversity of foods. As well as the foods that we eat, we want them to be wholesome, we don't want them to have toxic chemicals on them, and we do want them to be nutrient dense. But in the same way that the soil requires a diversity of plants in order to have a diversity of microbes in order to function effectively as a whole, the human gut also requires a diversity of microbes in order to function effectively. And the only way that we can get a diversity of microbes in the human gut is to eat a wide diversity of plant foods as well as whatever animal foods you like. I'm not saying you have to be vegetarian, but every kind of plant food that you eat is going to support different microbes in your gut in the same way that every kind of plant that grows in the soil supports different microbes.

1:26:12 So the research from the American Gut Project shows that people, Americans who consumed 30 different kinds of plant foods in a week, at least 30 different kinds of plant foods, have virtually no autoimmune disorders. By autoimmune disorders I mean things like heart disease, diabetes, whatever. I wouldn't be surprised to find it was also linked to immunity against things like COVID, for example. That we know that people who have a weaker immune response are more susceptible. That there are cofactors that go with COVID and one of those surely has got to be the integrity of the gut microbiome. So it's not only going to be what is the integrity of the foods that you're eating but how many different kinds of plant foods are you eating?

1:27:01 So if you would like me to send you a link to the American Gut Project, it was a citizen science project that involved more than 11,000 American citizens who participated in that project. And they found that people who ate 10 or less different kinds of plant foods in a week had very simplified gut systems or very simplified gut microbiomes and they had very poor immune response. They were more susceptible to just about everything that was going, probably including COVID, although at the time that that research was done we hadn't heard of that at that stage.

1:27:41 So I think it is very important for people, just forgetting about soil for a minute, for people just to eat a wide diversity of plants and also to make sure that those plants obviously are grown in healthy soils. The other thing too is that if you're eating some green plants, in other words you're not cooking them, like herbs like say parsley or cilantro or something like that, you can actually the microbes that are endophytes that are within those plants can pass through your digestive juices in your stomach and can get down into your large intestine, which is where basically where your gut microbiome is, and improve it, improve the diversity of it. So eating some green things that have actually got microbes in them, so you know an iceberg lettuce grown with lots of nitrogen and phosphorus is probably not going to help you a lot. But if you had some nice herbs that were grown in your own backyard in biologically active soils, they can definitely improve the function of your human gut microbiome.

1:28:45 And the thing about that is that the microbes that are in the human gut are able to switch genes on and off in our bodies. That's where it's really powerful. So they can switch our genes on for immunity or if we don't have sufficient diversity in our diet and we don't have the microbes there, then the genes that we need for immunity won't get switched on. In fact that's a good question because my brain is now just connecting the dots and it's probably almost exactly the same as what's happening with citrus greening in Ed James's citrus grove, for example. He has a diversity of plants there, which means there's a diversity of microbes there, which means his citrus trees are able to access those microbes and utilize them for immunity. If there was no ground cover there, there are no microbes that they can call on when they need them.

1:29:42 So if we have the diversity of plants and we have a diversity of microbes in our gut, when we need them for something, because at least 80 percent of our immunity comes from our gut, some people say even higher but it's a minimum of 80 percent of human immunity comes from your gut microbiome. If you have a diverse gut microbiome and if those microbes are able to switch genes on to help you, like actually switch human genes on to help you fight disease, it's really, really important.

1:30:11 So that's a very good point I think to end the series on because after all it is about food production, isn't it? We're growing, we're hopefully growing most of them for food production. I know some of it goes into ethanol but especially when we're talking about orchards and vineyards, we're talking about food production. So even just having you know a diverse interrow in an orchard or a vineyard is going to improve the quality of the fruit or the nuts that are produced in that situation, all the vegetables. That's the case. Maybe. And Stephen makes a good point talking about the grazing animals that graze on diverse pastures are also full of you know those same nutrients. So even the meat that you're eating as well. And so I think that's a good thing.

1:31:03 Yeah, also more, like the essential amino acids are going to be in the right kind of, you know, omega-3 rather than omega-6. There'll be much more omega-3 in that meat if animals are grazing on pastures, diverse pastures, for sure going to be much healthier for it. And the milk and the butter.