Growing a Revolution: Bringing Our Soil Back to Life - David Montgomery

Thank You Jane I'm very excited to introduce our next speaker David Montgomery a MacArthur Fellow and professor of geomorphology at the University of Washington David is an internationally recognized geologist who studies landscape evolution and the effects of geological processes on ecological systems and human societies an author of award-winning popular science books he has been featured in documentary films network and cable news and on a variety of TV shows and radio programs as well including Nova PBS newshour Fox & Friends and all things considered when not writing or doing geology he plays in the band big dirt this is what I want to hear more about he lives in Seattle with his wife Annie and their black lab guide dog dropout Loki let's hear it for David [Applause] all the way back yep yeah I'll get you from the beginning great thank you well um I'm honored to be here to address this meeting and I'm on West Coast time so if I'm a little shaky at the start it's not because I'm an academic from Seattle it's because it's 4:00 a.m. but my job today I think is really to talk you through a journey that I've been on because I'm a geologist as was mentioned by training I trained as an undergrad as a hardrock geologist and then I got into studying landscape evolution and discovered that that stuff that covered up the rocks the soil is actually really kind of important for shaping landscapes and studied manage to study soil erosion around the world for a few decades and really have gradually come to see this soil health movement as something that is really important really critical and really exciting and I wrote this book dirt erosion of civilizations up there in the left hand side of the screen about 10 years ago now and that's the kind of a book that you might expect a geologist to write about soil it's very backwards looking it looks back through history it looks back at the most recent period of geologic time the part that we've greatly shaped and influenced and I struggled hard with how to write the last chapter of that book and I'll give you a flavor a bit of a taste for that over the next few minutes but it basically looks at defining the problem of what is has been the problem with the way that people have treated land over the centuries and the problems that soil erosion and soil degradation have caused for human societies that middle book the hidden half of nature that I wrote with my wife who's a biologist was really our exploration of learning the role of microbes in soil fertility the part that we weren't really taught when we were in graduate school and how that opened our eyes to potential solutions to the problems identified in the dirt book and that third book growing a revolution is the most recent one and that essentially was the story of me going around the world and listening to farmers who had already restored fertility to their land and trying to connect the dots between this long term pattern of soil degradation the new science allows us to understand the role of microbes and soil fertility and the practical applications of what does that mean for the world's farmlands so and if anyone's live tweeting our handle is at dig to grow as is up there on the screen encourage you to spread the word to people outside this room but let me start since I am an academic with a pop quiz which planet would you rather live on the one with air and water and that third thing we often forget to mention soil or that red one over there I vote for Earth and if you if you look at the nature of the soil on Mars we're not going there to farm anytime soon it's battery acid it's gonna be you know despite what you may see in the movies it would be really hard to generate an agricultural civilization on Mars that confluence of a breathable atmosphere freely abundant water and healthy fertile soil is really what has promoted life on this planet for a very long time once life left the oceans and colonized the the areas that we can actually inhabit quite readily so this gives you a bit of a hint for why a geologist like me it would be very concerned about the state of the world soils this this map that's up there now is the UN's global map of soil degradation from a few years ago now and you'll notice there's an awful lot of yellow and red zones on that map areas where the land has been degraded in terms of its agricultural potential I also want to point out that despite the kind of the ominous look of that color on this map you can go in to each of those red zones on the map and find farms that are building soil fertility they're absolutely turning around the picture you would take home from the broad pattern on this map so in this talk I'm going to try and take you on my own intellectual journey going from somebody who looks at the broad picture this map and goes oh my we're in trouble to somebody who thinks oh yeah we can fix this and why do I know that because I've visited farmers around the world who have already done it on their own land that it's not a theory that it could be done but first I'm going to spend probably about 10 minutes either depressing you or just reviewing things that you already know because there's a study of it in terms of the state of the world soils and there's a study that David Pimentel and his colleagues at Cornell did a few years back now that tried to tally up the the the the magnitude of the dagger soil degradation due to anthropogenic human influences on this planet over the the time of the second the second half of the 20th century and they basically wrote that some four hundred and thirty million hectares of land had been abandoned between the Second World War and the end of the century around the world that's an air and that had been abandoned agriculture once productive farmland that was no longer in in agriculture that's an awful lot of land that's about a third of all prep cropland and that's about an area the size that's the of India and China combined and if you really look at this in the way that I'm going to the next few minutes this would actually be an underestimate because it's not including the land degradation that occurred in ancient times and you can quibble a bit perhaps about their numbers of the trend but it's a scary large amount of land around the world has been taken out of agricultural production because of the way that we have degraded it and if you look at the most for the most recent assessment of the state of the world soils on one that came out in 2015 from the United Nations in their global state of the soil assessment you burrow into there and you read it and you find that they assess that humanity is losing about 0.3 percent of our global food production capacity each and every year to ongoing soil that erosion and degradation that's kind of a slow rate right 0.3% sound kind of like what we're all getting for our savings accounts it's it's it's not a big number but it adds up over time if you take that number you project it out another hundred years we'd be on track according to this report to degrade about another third of our agricultural production capacity and a hundred years to a geologist is not a very long time it may be absolutely forever or over forever horizon in the political world but in the geological world that's roundoff error on tomorrow morning and so if we've already degraded something like a third of the world's cropland and we're tract the way things are going to degrade another third in the next century it's my contention that agriculture is going to need to change and that's why I'm so excited about this idea of soil health what Howard Buffett is called the brown revolution a soil health revolution there's lots of terms we could throw at it but the fundamental idea under that idea that vision of his is really sound and I think really important for the future of humanity for these very simple reasons we need to turn around to rate the degradation of agricultural land and we have this century to do it maybe we only have enough you even have a few decades but as a geologist I tend to be a little patient about those kind of things but there is an urgent need to address this problem of ongoing soil degradation around the world and actually not slow it not just slow it down but reverse it and I wrote about the first part that sort of the pattern and history of ancient societies in that dirt book and it was an exploration of going into the archaeological world reading archaeological papers visiting areas around the world where soil had been degraded and really trying to put the story together of how the way people treated land affected the way the land would treat people over time and I was actually trying to update a great book that was written by some soil conservation service scientists back in the 1950s called topsoil and civilization I know if anyone had read that book but I read it as an undergraduate in college I loved it it convinced me that soil was something worthy of attention and interesting even to a geologist and in trying to update that book what I did is I looked at the role that soil erosion played in ancient societies and it played a really major role in the demise of ancient civilizations from Neolithic or Bronze Age Europe to classical Greece Rome the southern United States Central America and more that I catalogued in that book and there was a problem I realized with with the usual explanation that you find in environmental history textbooks and which is that deforestation led to the destruction of soil to the erosion of soil that helped undermine ancient civilizations and I've done a lot of work on soil erosion on the west coast to the US and in steep lands around the world and I can assure you that that clear-cutting steep slopes leads to accelerate soil erosion but it does it in a very small portion of the landscape there's very sensitive areas that you can identify and the numbers simply don't pencil out in terms of erosion rates following timber harvest to explain the wholesale loss of soil that we've seen in ancient societies around the world and I started to realize that there was actually a different culprit in the in the history of soil erosion it's affecting human civilizations and it wasn't the axe that caused erosion it was the plow that followed and so if there can be a villain in a nonfiction book the villain of my dirt book was the plow this is not what I expected to be learning when I started writing that book I thought I was just gonna read up a fun bunch of archaeological things maybe get to travel to some neat parts of the world learn some ancient history I came away realizing that I was writing a history of farming and essentially a case an argument for ditching the plow for no-till farming and why is it that the plow led to such accelerated soil erosion well think about what a plow does I mean it's exceptionally good weed control write it in inverts the soil takes out what's growing on the surface but it also gives wind and rain a fresh surface to work on it also reduces soil structure pull of lorries as the soil a bunch of other things that soil scientists would love to argue and think about but the way it geologists like myself thinks about it is that the soil that the plow essentially changed the relationship between soil erosion and soil production from one that was naturally in balance to one that was out of balance how many of you ever gone out to a native grassland or forests around the world and seen a whole lot of bare earth you don't nature clothe herself in plants and there's this long relationship between vegetation and soil that you can trace right back to the when plants came out of the sea and started colonizing land and the organic matter that they thought that the plants built up built the quality of the soil up that fertile soil helped plants grow and we were off and running in terms of terrestrial ecosystems the plow fundamentally alters that on the land that we have in society after society depended on to grow our food and if there's one thing that I kind of know from economics and this especially from looking at my own personal finances it's that if you use something up if you spend faster than you have you replace it faster than you have income you're burning up your savings and at a societal level the soil is our natural capital it's our society's bank account and soil erosion that proceeds faster than soil building is quite literally drawing down our natural supply of capital and this is a print a problem in societies around the world I'm gonna pick on my own home state of Washington for a minute simply to illustrate the point of why a geologist like myself would look at a picture like this of a winter wheat field on the Palouse in eastern Washington from back in 1970 and and think that you know the soil is just absolutely bleeding off the landscape all those little channels those little rills that happened you know after the field was plowed before the next crop came back in and this I believe it was a winter wheat fallow rotation in this case you know those little channels are kind of an agricultural nuisance you can erase them with a single pass of the plough but what happens if they come back each and every year they really start to add up and the second picture also from the Palouse illustrates the magnitude of that kind of effect that fence up in the upper right hand corner of the slide is a fence that the farmer built around their water cistern back in 1911 when the when the native grasses were first plowed to make way for a winter wheat fallow rotation which is all that happened in this field for the next 50 years and you'll notice that there's a bit of a cliff around that that fence that does result a result of those little rills each and every year coming in and the action of the plow moving soil away from the fence line in downhill what you can't really see terribly well although on this negative is that there's actually a kind of a washed out survey rod in there and there's a little black bit that let's see if I can actually point to it it goes from about there to there that little black thing there that's actually a 1 foot increment on a stadia rod a survey rod that cliff in other words is 5 feet tall 5 feet of soil erosion in 50 years is about a foot a decade that's about an inch of erosion every year and I'll show you data in a minute that should convince you that well there's nowhere on earth that soils form at a pace of an inch a year except perhaps in my wife's garden and perhaps on your farm because we can actually form soils faster than nature doesn't you know that's something that was quite a revelation to me but we'll get there that's in the second book and I'm still in the depressing part so you should be sitting there thinking a Dave isn't that a pretty extreme example and of course it is that's why I like to use it how typical is it and how could it be you know and and that was like one corner of one farm what about whole regions well this I'm going to use one example I have lots of regional and national examples in the dirt book but I'm going to use the southeast of the United States the Piedmont region the the upland hill country from Virginia up there in the upper right and Alabama in the lower left one of the original agricultural powerhouses and bread baskets of the American colonies and what I'm showing you in that gray noodle is the amount of topsoil that's been lost since colonial agriculture began so you know roughly 200 years to 50 or so of integrated soil loss and you'll notice there's four to ten inches that graze stuff around most of that region and the black stuff is more than ten inches of topsoil erosion well how big a deal was that if you go back and you actually read the journals of the some of the original farmers that first worked this land there's only about six to 12 inches of rich black earth in the forest soils that were first cleared for agriculture in other words we've eroded off anywhere from a third to darn near all of the topsoil across a pretty wide swath of what was originally one of the big agricultural regions of this country and that starts to put into perspective we did which is 200 year run at the plow that starts to put into perspective the idea that with a thousand year run at southern greece the ancient greeks could quite literally plow the soil off their land you can still find areas in the bare hill country of southern greece where there's a gibran agricultural implements abandoned on areas that no longer have soil at all it puts into perspective how the Romans could have ploughed off the soils of central Italy with an 800 year run at Central Italy and how many of you have ever been to the ancient port of Rome Ostia it's nowhere near the coast it's miles inland why because the soils of central Italy were washed down at a faster rate than they normally would forming the punt the famous pontine marshes and pushing the coastline out from where the port was you can go stay on the old docks of Rome and the sea is not visible and so it starts to put into perspective that the idea that agricultural soil loss and erosion maintained over generations could really add up to have major effects on human societies and if you look need to look no farther today than places like Syria and Libya to find places where the long-term legacy of soil degradation is still playing out to the detriment of the local population you can go to Syria for example and look find Roman tax records that document great harvest of wheat off land that's barely able to support a population today societies to destroy their soil take their own foundation out from underneath them but there's also another change in soil that's not just related to soil erosion this shows you pictures of two soils from North Carolina in that gray bubble on the previous slide that I showed you and one of those soils is from a modern conventional tobacco field it's actually off of a Research Station the other one shows you the soil from the forest next door which would you rather be farming one of them is basically beets and with salt in it the other one is soil that has a lot of organic matter a lot of life in it one of them is fertile the other its production is maintained by external inputs because its internal fertility has been depleted its soil organic matter has been depleted there's farms that I visited in North Carolina where the top so is quite literally gone and people are farming the B horizon the subsoil and if you add enough ad inputs to it you can coax a good crop out of it but you're fundamentally hooked on and dependent on the inputs if you take out the natural fertility the soil what have we done to the soil organic matter in the United States so far we've depleted by the estimates I've seen roughly half of it we've burned through about half our natural capital in a couple hundred years globally it's about the same statistic you can argue about whether it's 50 or 70 percent I've seen estimates even up to 80 percent but I'm gonna go with half that's scary enough and it's on the low end of estimates so this really motivates well I motivates the questionable how typical is this around the world and in writing the dirt book I did a lot of work looking at the agricultural sorry the archaeological story but I also wanted to look at modern data to try and see if the numbers of for modern studies that have actually documented soil loss and erosion and degradation off of fields do they add up to enough to actually help explain the wholesale loss of soil off of regions around the world in the past because we didn't actually have what I got went back and researched Roman agricultural soil loss there's only four books that survived about Roman agriculture and they're kind of cryptic and vague they're wooden people they're actually collecting data on you know sediment flux off of Roman fields but we had that kind of data today so I want to figure out how do the numbers pencil out so I went to the literature and did something that was a bit unusual to these days I guess and that's I didn't just sort of Google the first ten you know like returns on soil erosion I went to the library for about a month and I dug up every scrap of data I could find in that period and why did I only spend a month doing it that's all the time I had so here's what I found I basically found 1,400 studies and I published the results of this in the Proceedings of the National Academy of Sciences the same year the dirt book came out back in 2007 if you want this kind of a data you want to see what's behind it go look that paper up there's an Excel spreadsheet online you can take it steal it nobody should ever have to do this exercise again and compile this data again so what I'm showing you are the measurement types on the left hand side and the median or the average value on the right hand side and a median is that kind of average for half are smaller half are bigger so it's just the middle number ank number and the numbers in parentheses after the labels on the left that's how many peer-reviewed academic studies are used to generate that average so you know in other words I did a fair amount of homework is it comprehensive no there's a lot more data one could pull into something like this but I did due diligence on it that number at the top is the bad news number that's the erosion rate off of conventionally plowed fields as a global average so it's everything from subsistence farming that uses a plow right on up to modern mechanized stuff at large-scale in North America and you'll notice that it's about a millimeter and a half a year is the globally averaged erosion rate off of conventionally plowed fields now a millimeter and a half a year sounds pretty slow your fingernails grow ten times faster than that the San Andreas Fault moves 40 times faster than that and I've never seen it move and hopefully it won't but it's a scary big number to a geologist why because of those blue numbers at the bottom those are the erosion rates under native vegetation globally averaged so these are thick fuzzy glasses of a geologist not they don't apply in any particular farm they're just the global average but erosion rates under native vegetation rates that soils are produced naturally and long-term geological erosion rates are all about the same percent or two of a millimeter a year that's like twenty to a hundred times slower than a rate of agricultural soil loss off of conventionally plowed fields and those are those USDA T values I don't believe it for a minute they're kind of meaningless the good news number is that number for no-till agriculture that doesn't involve the plow I've colored it blue because it's really a lot closer to those numbers at the bottom we can be essentially I think we know how to solve the soil erosion problem is to stop plowing it's to go to no-till practices and that's sort of the foundation for agricultural sustainability is don't lose the soil and foregoing the plow is a way to actually do that you can also run in your mind's eye the sort of experiment or on the back of a napkin if you want what the data that I've just shown you means for that the hypothesis I was looking at in the dirt book of could agricultural loss and degradation take out ancient societies could that have been one of the cause one of the contributing factors to the demise of societies so if we take that net soil loss of about a millimeter a year and recall I had about a millimetre and a half that I could showed you is the average let's go conservative we'll go for just a millimeter a year difference between those numbers it implies that you could erode a one to three foot thick or 1/2 meter 2 meter thick soil in about five hundred to a thousand years which again to a geologist is really fast to a society that's kind of slow as generations you don't it's hard to notice over one lifetime but it adds up over just a few generations and that that timeframe that sort of thousand-year rich kind of timeframe is is about that it's approximately the lifespan of most major agricultural civilizations with some really key important exceptions those are the major river floodplains of the world places like the Nile the Tigris and Euphrates the Indus and the Brahmaputra in India the rivers of lowland China in in Asia those are places where agricultural societies have been able to maintain tillage based agriculture for thousands of years for a simple reason their floodplains they get fresh soil delivered every year to their door by rising waters as long as you don't dyke the rivers off and prevent floods from happening which got Mesopotamia into trouble and has caused trouble agriculture in other regions of the world but it's kind of aside the point I want to make here what I want to do is draw your attention to the regions in the headwaters of those long-lived societies because these are areas where soil erosion has actually you know crippled societies over time places like Syria in the mid in the headwaters of the Tigris and Euphrates Somalia and Ethiopia in the headwaters the Nile the Himalayan the headwaters of the big rivers in India or the eastern edge of the Tibetan Plateau which was the original seat of Chinese agriculture and was abandoned centuries ago due to soil loss and degradation as people move down onto the regularly fertilized floodplains so the problems that those societies have had over the long-run kind of help illustrate that soil loss and erosion in the headwaters of those systems was subsidizing civilizations down on the river floodplains so that's kind of the end of the really depressing part of the talk because I started grappling with the question of whether soil restoration is possible and whether we could reverse this historical pattern and that's something that I started grappling with really in writing the last chapter of the dirt book because what you will read in that book is my third attempt to write that last chapter the first two attempts were I deemed too depressing to actually put into print and I went back but okay what can I think about here that might be a little more optimistic well at the same time that I was writing that I was starting to learn about the fund of the transformative potential of thinking about the soil differently and particularly about thinking about that part of life in the soil that we don't see with our own senses that's out of sight out of mind below ground and out of touch with our own senses the microbial world and I wrote about that with my co-author and wife and McClay who's a biologist and in the hidden half of nature and if you think about what makes healthy fertile soil in the way we now know and understand it it's the marriage of geology and biology and we happen to have that going on in our own house and we figured and through observation and accident because we weren't intending to figure this story out we were we were trying to make a garden in part because Anna's a gardener and you know as a biologist who studied plants this is sort of her world I think of her as a plant whisperer I'm that guy in the office that if you give a house plant to it'll be dead in a month because I forget to water it and stuff and this is what you know you don't give a geologist a plant to care for but at but an is is really quite incredible with plants and we bought this house in North Seattle back in the late 1990s when I got tenure at the University of Washington we decided that Seattle was actually a pretty nice place after all and we would stay there we bought a house it had a lawn as sort of a side lawn that I'm showing you here and the note the neighbors you know the place in the back it'll-it'll up a little later but also note this you know when we peeled that lawn off that we had this really sort of rich fertile black earth that North Seattle's known for know we had glacial till we had really crap soil then we had dirt basically there was no life and it we didn't have a single worm there was no macroscopic life-forms we didn't see anything living in that soil and we build that lawn off and we kind of went oh should have dug a soil pit didn't think to do that when I was shopping for a house done that all over the world for research didn't think to do it at home we realized we had a problem we had dirt we wanted soil and wanted to grow a garden this was not the stuff that was really going to help and so she took it on herself to really start what in the book we'd termed the organic matter crusade because she realized we had the geological half of good soil we had a whole lot of India ground up pieces of British Columbia that had been bulldozed by a great Ice Sheet dumped down in Seattle and then overridden by a mile high wall of ice that's about three times the height of the Space Needle that compressed it into nature's concrete we had the raw stuff they had the raw mineral matter for good soil we didn't have the biology we're lacking the life so she started raking up our neighbor's oak leaves in the fall I hope you surprised how welcoming and nice neighbors are in the city when you come over with your wheelbarrow and rake up their leaves and take them away they didn't realize that they were just like giving us stuff to fertilize our yard and they were undermining the fertility of their own land the Seattle Zoo has a program where they give away what's called zoo do which is exactly what you think it might be it's the the composted turds from the herbivores and they have a lottery and we kept entering it and I had a pickup truck and so handled load my truck up with zoo do and we kept thinking wow we won again this is great and I think the reality is that you always win the zoo lottery but the so we basically were adding organic matter wherever we could get it and we started off with thinking that we just wanted to like mulch the soil to keep water in it because even in Seattle you have to water sometimes we first planted in August we had a bunch of little plants anyway we kept going with this soil composting and mulching regimen for a couple years and we started to notice within about three years that our soil is getting darker it had gone from that khaki beach color to the sort of a chocolate milk chocolatey and this shows you the soil pit that I probably you know should have dug when I bought the house but I dug this about three to four years after we had started the what the yard transformation and you can see that the leaves and the woodchips the the mulch that we put it on the surface and down at the bottom you can see we still have glacial till we didn't dig anything up we didn't rototill we just kept adding organic matter to the surface and we would find that it would be it would basically decay it would disappear over the course of three to six months we'd have to go scrounge and add more and what once we saw the color of the yard change and the codes of the soil changing it decided okay we'll dig a pit what do we have and you'll notice that ants pruning shears are there and in between that the surface compost and mulch and that and the till at depth we've got about two inches of halfway decent soil in just a couple of years this is beating nature at her own game in terms of pace of soil formation and to be fair a geologist tends to think of building soil by breaking rocks up but you can also do it by adding organic matter to already pulverized mineral matter and that's what we had in our yard and that's what we have on many farms around the world we are in some soil we're not just farming a rock the challenge is to get the biology back to get the organic matter back to bring soil back to life the subtitle of the new book and so here we've got about two inches of soil built in about five years that's what that's gonna be about four inches a decade that's more than a meter in a century you look at the global average soil depth in the UN global soil database it's less than a meter it's about seven five centimeters it's about two feet two and a half feet if you could rebuild soil at a global average kind of perspective in the course of a century that's remarkably fast and I'm not saying we could do that all around the world but I am saying we can do what we have up here on the screen now this is what we did in our yard in my right hand the one on what the left side of the screen there's the soil that we started with in our yard at a less than half a percent organic matter the soil in my right hand it's the same same dirt same soil it's just about 15 years later with the the composting and mulching and organic matter additions that we had in our yard and it's up to about eight to ten percent organic matter we've stored about eight tons for those who do carbon accounting we've spend about eight tons or so of carbon in our yard through our gardening practices and we did it basically to try and do this to make a garden and having a nice garden in our yard is transformed our lives the way we use the yard we live outside now basically in the summer or there's late nights in Seattle and so forth I won't bore you with the details of that but I do want to point out the neighbor's house back there we don't see it anymore they're lovely people but I got tired of watching their kids grow up much nicer to live in a city with a wall of green between you and the neighbors but we don't have to dwell on that the other thing that I learned and the Anna and I both learned and that really woke us up to what was really going on here was that sort of the stars of this transformation of our soil weren't an tonight we were kind of helping to facilitate it but we weren't doing the really heavy lifting on it that was going on below ground that was being done by microbes that was being done in the microbial world and one of the things we learned and starting to look into because we're both scientists right so we see this transformation our yard we see organic matter disappearing what's going on here so we dig into it and we realized that there's this zone around the roots out of the plants called the rhizosphere that is one of the most life rich zones on the planet you want to go find a whole lot of microbes dig around the root zone of a healthy plant it's they're surrounded by microorganisms much more so than a distance from roots and a big part of what's going on there is something that that our eyes were open to in researching this book and that is that what we were taught in terms of what plant roots do was only half the story because we learned that plant roots are you know essentially straws that help facilitate acquisition of nutrients from the soil but they also push stuff out into the soil things called exude AIDS which many of you have probably heard of and which consists of things like sugars carbohydrates you know plants have a monopoly on being able to turn carbon dioxide and water into carbohydrates and they have this wonderful side effect of pushing oxygen into the atmosphere which we all appreciate but they also build a botanical world that way they have a monopoly on being able to do that but they will push out up to about 30 to 40 percent some plants 30 to 40 percent of the material they build through photosynthesis they'll push it out of their roots into the soil as exudates they exude it into the soil and what are those materials that's the carbohydrates the sugars that I mentioned it's also proteins they'll do hormones but last year there's a paper that came out or people documented plants pushing fats lipids out into the soil what are carbohydrates proteins and fats that's food lunch breakfast dinner it's food basically plants are pushing food out into the soil and they're not doing it simply because they have too much food they're doing it to feed those microbes in the soil those microbes the reason that the rhizosphere is such a licensed dentist own is not because pests and pathogens are gathering to attack plants they're gathering because the plants are setting a subterranean buffet for microbes no why would plants do that how many of us give away thirty to forty percent of our annual income other than taxes that is [Applause] or maybe there is a good analogy there maybe the plants are taxing themselves to actually support this microbial their microbial assistance out in the soil that couldn't survive without the food that they're getting from the plants and the plants get something in return kind of the way that we get roads to drive on and an art and a military to protect us there are some benefits from being taxed we could argue about the level but that's not what we're gonna do today but there's there's something that's going on in the rhizosphere is that there's a biological bazaar going on there's interchanges and interactions between the microbial life in the soil and the plants and this shows you sort of a blow-up of what an and I've turned the the biological bizarre or microbes and plants are trading nutrients metabolites and exudates and and in that centerpiece where you see that root coming down with the blue thing is that the rhizosphere where you've got all kinds of bacterial and fungal life the plants are pushing the exudates out into the soil those black lines and that stuff doesn't stick around very long it gets consumed it gets about a millimeter to a centimeter about the thickness of my thumbnail to the length of my thumbnail out away from roots into the soil before something eats it and what happens to stuff that gets eaten it gets metabolized and what happens to the waste products of metabolism and organism will excrete them and so we have all these microbial metabolites coming back out into the root zone of plants right around roots because that's where they're living and things are being consumed what are those kind of metabolites when Anna and I learned that those include things like plant growth promoting hormones we were astounded because here you have microbial life in the soil bacteria in the soil producing hormones to make plants grow and to keep plants healthy think about that that's one sort of whole kingdom of life making fundamental compounds for that would promote promote the health of a completely different kingdom of life the only reason they're doing that is these are mutually beneficial exchanges true symbiosis partnerships between life and the soil and the plants that are growing in it and these plant these partnerships go back to the very dawn of life on land because the first plant fossils that we have examples of have mycorrhizal fungi intertwined with their roots the fungi held these partnerships help the plants come ashore and colonize the continents roots originally were simply structural supports the fungi fed the plants roots evolved the things their behaviors that I was taught in graduate school later these are very deep evolutionary partnerships the the and when and I realized the the functionality that microbial ecosystems were providing to plants in terms of nutrient acquisition in terms of teeing up their defensive systems in terms of chemical signaling all mediated through these partnerships and exchanges in the rhizosphere right Wow this is kind of how nature works when we realize that the human gut works the same way just inside out that's when we wrote the hidden half of nature because this really is fundamental to understanding what creates the health and nutrition of not only our plants but our own bodies and I'm not going to talk about the human colon today you can read the book if you want to get into that but the parallels with what's happening in the root zone of plants are actually striking and what does this mean for how we think about plants well we need to think about them having a diet and if you think about what these partnerships mean if you have a a plant that's growing in a organic matter and nutrients all you can support it you can grow it on a fertilizer diet you can feed it the NPK that it needs you can feed it a lot of it and you can grow big plants you can get big yields we all know this and in fact if you have degraded soil that's a ret you know one of the reasons that intensive agriculture to modern agriculture and 20th centuries we had already degraded our soil organic matter in fertility of lands are in the developed world but what does that do to the plants plants don't put out as extensive a root system if they're getting most of the macronutrients they need and and I turn that those that behavior couch potato crops they get kind of lazy they don't put out the root system the same root system that means they're not putting out as many exudates that means they're not recruiting as many they're not exerting the same Selective pressure on the soil life so they're not getting the same composition of beneficial organisms and the soil as they would if they were growing in a very organic matter rich and I term here the soil health diet which can you know you could still fertilize them if you're basically a need to add NPK to it but by having a healthy fertile soil you're getting more in the way of the micronutrients that the fungi will provision for the plants and you're getting more of those beneficial microbial metabolites that promote the health of the plants so here we have a fairly simple explanation perhaps for why the global demand for pesticides went through the roof as the global use of fertilizers went through the roof we disarmed the defensive systems of our plants and that's not to slam fertilizers but it's to basically argue that we need to think about the way that plants eat and defend themselves and nourish themselves what makes plants healthy because the connection between say healthy soil and healthy plants is actually now pretty clean and pretty clear in terms of the academic literature and so in think as an my eyes were open to this new way of sort of thinking about soils and soil health in our yard we started to think about well how could these ideas apply around the world to farms around the world could we basically apply these same kind of lessons to rebuild the health and fertility of the world's farmland I started first thinking about this actually when I gave a talk at the world conservation agriculture Congress I think in 2014 and Howard Buffett was one of the other speakers speaking about his idea of a brown revolution and that really inspired inspired me and resonated with me about that yo Wow could we basically take these ideas and as a geologist I sort of figured this is a good excuse to do a little field work and I never thought when I was in graduate school that field or could involve going around and visiting farms and asking farmers how did you change your soil what did you do what are your practices okay and let's take a shovel let's dig a hole on your land and your neighbor's land and see what happened and that's basically what I did is they visited farm took about six months off visited farms around the world to basically ask these questions of of farmers who had already rebuilt the health of their soil what did they do what were the principles behind what they did and what I found was that farmers who had adopted the principles of conservation agriculture which will define in a moment that that was the common element between farmers who had really radically improved their soil in remarkably short order and that they could match conventional crop yields using far less oil and chemical inputs and I visited one organic farm and visited the Rodale Institute I've been in mostly visited conventional farms because I wanted to see what the magnitude of the change could be there so what are these principles these three principles that worked you know across the board on the organic farms and on more conventional ones where you know we're not a secret I didn't make these up there minimal or no disturbance the direct planting of seeds are going no-till theirs maintaining a permanent ground cover rigging it raising cover crops and retaining crop residues and adopting more diverse rotations to help break up pathogen carryover these three simple ideas were the common elements between the farms that around the world that I visited that had radically improved their soil and all those little microbes around there on the screen are meant to remind me to basically say that you know the reason that these practices work is this is a recipe here for cultivating beneficial soil life don't disturb it don't break up those mycorrhizal fungi feed it organic matter feed it carbon give it something to eat and and don't allow just one or two species an opportunity to really take advantage and attack something if you plant corn in the same field year after year you're inviting corn pests to dinner what you want is a diverse community of life in the soil to help keep corn pests away from your plants so anyway these these are the basically the basic ideas that underlie the principles that underlay the farms I found to be very successful this and many of you probably know David Brant he was one of the key people that I visited he'll come back in a few minutes but basically you know some of the things that well let me actually go back to this list those bottom two cover crops and crop rotations those are not new ideas those are ancient ideas you can find examples of that in societies around the world Thomas Jefferson was all about cover crops and crop rotations but he also invented that plow that still graces the seal of the USDA for some reason oh did I say that Jefferson was brilliant right he also invented a good contour plow fabulous invention but what's really unique about combining these three elements together in a new system of farming is taking that ancient wisdom of crop rotations and cover crops and getting it to work with the modern technologies that allow us to do minimal disturbance or no-till you know things from the herbicides that we have to to cover crops and and the kind of thing that I'll show you from from Rodale in a moment to sort more ecologically managing weed suppression getting modern science and ancient wisdom to work to align to implement these three principles is really the key thing and so part of that are new technologies like this is like David Grant the no-till planter that Brandt is showing off here and the thing that I found so interesting about this is the right-hand side of the screen is a freshly planted field now compare that in your mind's eye to what I was showing you from Eastern Washington in terms of you know freshly plowed fields there's no bare soil you can barely even tell the ground was disturbed that's a sea change in thinking about how we prepare the ground for planting and for soil and it can radically basically cut erosion off at the knees if we think in terms of managing cover crops Jeff Moyers who's here but then did me the favor of modeling his roller crimper here out of the Rodale Institute when I was researching the book you know there's new ways and new ways of thinking about how to actually generate weed suppression rather than using the using a plow so there's new ways of thinking new new technologies that we can combine with with different ways of thinking about how to treat the soil how to sequence things and I'll show you a series of I think for farmers that were very influential in my own thinking Dwayne Beck here from Dakota Lakes research farm was instrumental he's the first farm that I actually visited and that was practicing you know cover crops along with no-till and heat why did I go visit Duane he was also at I think at the 2014 conference I saw him give a talk either there at another one and was like I got a visit this guy's if I write that book he's doing very interesting stuff he was kind enough to give me three days of his time took me on a several hundred mile driving tour around his neighborhood around Pierre South Dakota which not coincidentally is the area that I showed on the cover of the dirt book in the heart of the Dust Bowl I a saw only a couple plowed fields in an all-day drive which is the point he wanted to make this region has been transformed in terms of going to no-till the black soil doesn't blow every time the wind comes up anymore that is a major change and what happened in terms of their agronomic practices by adopting no-till cover crops and complex rotations that you know gradually over time and experimenting with it they're able to greatly reduce their uses of diesel fertilizer and pesticide by more than half in most cases and that really impressed me because basically they'd figured out a way to grow just as much by using less and you'll notice what happened to their yield so they knew all their inputs went down that saved farmers money they were also able to farm whole farms rather than having a like a wheat fallow rotation they're able to actually grow something on all their land every year which is a major productivity boost but even in a traditional sense their yields went up you can check out their soybean and corn yields in this one example that I pulled for my notes on one of his test plots if you can spend less to grow more that translates very directly even a geologist can tell you that that translates into better on-farm economics and don't take investment advice from me but even I can recognize a good opportunity so when I left a Beck's farm I basically asked him well you know this is pretty impressive we'd visit some - like what twenty thousand acre farms if I recall in that you know some large operations I asked Duane how big you know could these ideas translate to small subsistence farms in the developing world in Africa say because that's where really the problem of feeding the world lies for the next centuries is how to feed Africa and the population is expected to grow there and he said you know don't ask me go talk to Kofi Bowie he's already done it so I got in a plane went to Ghana an equatorial West Africa to ask this gentleman here who has this wonderful got dirt gets oil hat which I got out of the cars first thing I see about him was I like this guy he's like on the right track and he has a farm that is basically practicing diversity in terms of what's being grown on the site at one time very small farms you know that individual farms are smaller than this room that we're staying that we're in and they're mostly subsistence farmer cities working with who don't have the resources to buy a lot of fertilizer or a lot of pesticide or a lot of agricultural implements they mostly have their own labor to work with and what he's been able to do is by getting them to you'll notice that on the fields there there's multiple crops there's plantains there's peppers and there's other things growing in that field what you don't see is bare earth what Kofi has been able to do at the no-till Center in Kumasi is to transform the practices of the farmers in his region from their traditional slash-and-burn practices which once they ran out of new land to clear and they were slashing and burning on the same land over and over that's a recipe for degrading your soil in your soil organic matter over time slash-and-burn only works if you can walk away you know farm for a few years then walk away for a few decades and let nature fix the land but what by adopting these practices of no-till with cover crops instead they were able to curtail erosion you'll notice their erosion rate went down by a factor of about 20 there but look what happened to their yields the corn yield tripled their cowpea yield double that's as good a boost to production as was achieved in the Green Revolution but this was done with no inputs no additional cost this was done with the change in thinking this is done with applying the principles of conservation agriculture and this was actually one of the first places that I saw that the demonstration of you know putting water applying water to fields that were treated in different ways and looking at what runs off and what sinks in they had a very nice example of that there so the third third farmer they'll share again do you probably you all probably are familiar with David Brant and his farm in Carroll Ohio I like to show this to audiences that are not farming audiences because people will look at that daikon radish and think farmers market but no David is a is a commodity corn and soy grower he grows a lot of other stuff on his farm but he's sellin corn and soybeans but he's growing at things like that daikon radish that would sell for an unspeakable amount at the Farmers Market in Seattle but David grows that to feed the microbes in his soil he kind of considers himself a bit of a microbe rancher I think and he walked me through the example of what he's done in this farm where he's gone no-till for 44 years ever since he came back from a stint in the Marine Corps in Vietnam and he's then adopted cover crops and has been diversifying his rotation his field there behind he has a mix of ten or so different cover crops in it that he pulled that radish out for me but I also want to point out the field across the road his neighbor's field behind him it's kind of yellow it's it's that's kind of a sickly soybeans at the time I took the picture but the green stuff in that field or glyphosate resistant weeds they cover up to about 25% of many of his neighbor's fields by my visual estimation that's a direct hit on their yields David doesn't have any weeds didn't see a single weed on his farm saw an awful lot of cover crop so he plants weeds he grows weeds and he kills them before they go to seed he calls them cover crops he's using them to get mineral elements out of the soil the subsoil into his topsoil so he can kill the cover crop so the nutrition that they've derived from the soil will go back into the topsoil and essentially fertilize his cash crop so he ran me through the economics of his and his neighbor's operations and this is where I really started to become a bit of an optimist that these kind of ideas could take on because well let's walk through the numbers his neighbors are doing full tillage 200 pounds 2n per acre two and a half quarts around at per acre the total cost he estimated about 500 bucks an acre the the county average yield was on the order of a hundred bushels an acre according to David the year that this which I think was 2015 and if 4 bucks a bushel that means his neighbors were losing 100 bucks an acre that's a great business bluntly I found a paper when I was saying you know kids and what you do as an academic is you trust but verify you sort of like get stories and then you go out and go what are the academic that might back this up there's a paper that came out that showed that farmers in Iowa in 2015 I believe it was that 25% of them lost money on every acre they planted think about that if you can basically have farmers armed with some of the best technology in the world and some of the best farmland in the world that are hardworking people and the more they work the more money they lose something is fundamentally wrong with our agricultural system well let's compare that to the economics of David's farm 44 years of no-till with cover crops he's not tilling it all so he saves on diesel he's using 24 pounds of nitrogen an acre he's not an organic farmer he'd probably hit you if you called him an organic farmer but I tart teasing him that he was an organic ish farmer because he's hardly using any fertilizer and he's hardly using any Roundy glyphosate one quart per acre about 1/5 of what his neighbors are using he's just not using as many inputs and his total costs are a lot lower therefore he spent about 320 bucks an acre that year his yield was well above the county average and it resulted in about a $4 Oh add a $4 bushel price he was making 400 bucks an acre it's a $500 an acre difference between he and his neighbors that's huge that's what started to get me turned me into a bit of an optimist not that these numbers would play out on every other farm but simply the idea that there are demonstrated systems now where farmers can actually maintain if not boost their yields at greatly reduced cost and the bigger the biggest cost is changing how they're thinking about the land how they're thinking about the soil the nature of their practices how they're approaching the problem Gabe Browns the last farmer that I'll talk about he's gotten a lot of press in the last few years in part because he's done amazing stuff on his land and he's a wonderful charismatic individual as well and he's actually bringing reintegrating livestock into his cropping operations and using cattle as a tool of soil rebuilding which as a geologist who'd studied gully formation in northern california I was trained to think in fact they did PhD work on those gullies demonstrated that it was grazing operations in the late 19th century that triggered all those deep gullies north of San Francisco if you ever gotten the Marin Headlands it wasn't between 1880 and 1900 that's they formed in my mind cows were bad cows equal to erosion I was wrong Gabe is the person who really convinced me by showing me how he had used livestock as a tool of soil regeneration the problem wasn't the cows the problem was how people were grazing in Marin County in the 19th century it was how we were managing the livestock and that makes sense when you think about what built the native grasslands of the Great Plains you know the Buffalo had something to do with it and so Gabe basically it was doing very innovative things of using his livestock to graze off his cover crops so you know if you think about weed control there's herbicides there's roller crimpers and there's also cows they can because they can eat them they could eat the cover crops they could eat weeds pretty happily - so he was bringing his cattle into his his Market Garden area bring chickens into then help manage the Flies by eating stuff out of that that the cow exudates they just invent a term but what I was really impressed by was what you can see with the shovel which Gabe called the most important tool on a farm and I think he's absolutely right because this shows you his soil in one of his hands and his neighbor decipher his neighbor's organic farm in his other hand and the organic farm is not that rich deep black one in this case that's Gabe's farm he's not an organic farmer he's another one of these what I call organic ish farmers just not using much in the way of inputs and so why the difference between his farm and his neighbor's organic farmer this neighbor's organic farm uses a lot of tillage they still use the plow Gabe was able to build this organic matter up to probably higher than the native soil over a period of years through his different management practices and I think he's using his livestock to accelerate the turnover and the breakdown of his cover crops and the reintegration of those nutrients back into the soil he's feeding the microbial life in the soil so what's the recipe that I can draw from all these lessons around the world my visit a bunch of other farms I described and growing or evolution as well but basically boiled it down to three simple things ditch the plow cover up and grow too versity and those are basically the principles of conservation agriculture is the UN FAO has defined them and you can use add livestock to the mix if you want as well I don't think that you have to do that to restore your soil but I think it can be a great of great value and an accelerator if done right and properly managed and if you think about these three principles and relate them to the principles that have guided modern conventional agriculture for the last 80 years or so this is a hundred and eighty degrees on all three points because we've essentially institutionalized at a global scale intensive tillage intensive chemical use and growing one or two crops functional monocultures you just go down that list and this is the opposite in terms of philosophy which is not to say that one couldn't plow every now and then or one couldn't use any agrochemicals but it's a basic a way of thinking there's a different way as our frontline set of thinking to approach each of these problems the problems behind these how you nourish the soil how you manage weeds and how you deal with pests this recipe really seemed to work and the bent in to restore fertility to the land and productivity to farms it allowed in the examples that I drew on for the book comparable if not increased yields this is not a question of the environment versus feeding the world we can grow just as much if not more by adopting these principles it resulted in reduced fossil fuel fertilizer and pesticide use it didn't eliminate other than on the organic farm that I visited it didn't eliminate these things but in all cases that resulted in higher farmer profits and these these principles applied both and worked with both or on organic and conventional farms and they increased soil carbon content that all the color differences in the soils that I showed you going anything that went from khaki to dark brown or black the difference is carbon soil organic matter they also result in better water retention or less off-site pollution all host of benefits and I want to emphasize that this is not really a question of organic versus conventional this suite of practices can apply in both realms of agriculture and I think if we can move the conventional agricultural world closer to what I term organic ish by reducing the reliance on inputs it could that is what could literally change farming and change the world and have lots of add-ons there's still going to be room I think for both styles of Agriculture into the future but what we need to think about is how to apply an understanding of soil ecology to rebuilding soil health to sustain if not increased crop yields using far less inputs why would we want it well what would that do to agriculture it would amount to another agricultural revolution so if you indulge me for the last minute or two of what I want to leave you with I want to basically try and explain to you why I think these practices could amount to a fifth agricultural revolution so what were the first four first one was agriculture the whole idea of cultivating and tilling the earth that was a revolution in the way that people treated the land and it set the stage for the rise of complex civilizations in different places around the world the idea that we could stay put and live in an area and support more of us was a radical idea it was incredibly successful but here we are the second agricultural revolution happened in different places around the world and that was realizing that taking care of the soil soil husbandry was actually important planting legumes in our crop rotations seemed to work we didn't realize about night the deal with nitrogen fixing bacteria to the 19th century but the idea of putting legumes and crop rotations was adopted by societies around the world long before that the idea of rotating crops cover crops these are ancient ideas and that quote from Leonardo da Vinci that's up there on the screen now we're know more about the movement of celestial bodies and about the soil underfoot how many quotes from science 500 years ago as this one is are as current today as they were when first offered we're just now learning the secrets of the soil as the NRCS puts it I mean our understanding of the role of microbial community ecology and promoting the health and growth of plants above ground has developed radically over the last few decades and our understanding of our microbiome the human microbiome and the parallels with that is really brand new there's a lot of stuff that we're just learning about the soil still the third Agricultural Revolution was mechanization industrialization in the 19th and early 20th century that greatly increased the amount of acreage under cultivation and a productivity of that land also caused a loss soil erosion but we'll skip over that for today the fourth revolution I lumped the green revolution of biotechnology into sort of a late 20th century technological revolution that really helped transform many aspects of agriculture I don't want to go into the details on that but what I want to basically point out is I think we're on the verge of what I'd like to think of as a fifth agricultural revolution and that would be a soil health revolution what Howard Buffett's called these brown revolution and I think that the this idea could be fundamentally transformative not just to agriculture but to human civilization and why do I say that I go back to that as the first book the dirt book if we don't get the it right this time around with our global civilization in terms of how we treat the land we don't have anywhere else to go to we simply have to get it right this time and the problem of feeding a 9 10 11 billion person world isn't just the next 20-30 years it's not just a problem of feeding everybody in 2050 it's a problem with feeding everybody from 2050 on and that we have to you know the farming practices that we have today that are termed conventional are simply not sustainable over the long run I think that the idea this the kind of practices that farmers demonstrated to me around the world and taught me about that would form the foundation of the soil health revolution these these new principles those could actually be sustainable by maintaining the fertility of our land and building it as a consequence of intensive agriculture what we could call a regenerative agriculture that would be transformative it would be a key moment in human history in our relationship not only with the land with this planet that's how we could become stewards of this world in ways that would allow us to persist there's other benefits that we get as well we could restore farm profitability over the short run I think it would help us feed the world over the long run it could help us put carbon in the ground which will help with climate change and it will also help with with off on and off site from farming activities and environmental degradation if we look at the future of biodiversity on this planet it's going to depend on what we do on farms because a quarter to a third of the world's land mass is in agricultural production however you look at whatever we're going to share this planet with it for the long run is going to reflect what we do on farms so I don't think that the soil health revolution in adopting these practices globally in terms of farmland will solve it's not the magic bullet that will solve all of these problems but it is something that will help address each and every one of them and I'm hard-pressed to think of another single solution the one could offer that would have this many side benefits when it actually looks like adopting these soil health building practices actually even today will pay for themselves in the current economy we're not talking environment versus the economy we're talking real win-win-win here and I've probably burned up my time so I'm gonna stop there I brought copies if people are interested in the books there'll be books downstairs on the breaks come by and see me if you want to talk happy to do that and Anne and I joined the social media world that's up there as well but in any case I thank you for your attention and for the good work that you're doing in trying to help rebuild fertility of the world's farmland so thank you very much [Applause]

Channel: undefined

Views: 22,619

Rating: 4.9166665 out of 5

Keywords: cover crop, cover crops, crop diversification, soil, soil quality, soil health, soil management, soil conservation, soybeans, corn, SARE, SARE Outreach, research and education, agriculture, sustainable, sustainable agriculture, farming, farm, research grants, ag, sustainable ag, organic, local food, USDA, stewardship, on farm research

Id: FZ22IV2tDvs

Length: 65min 58sec (3958 seconds)

Published: Fri Mar 02 2018

Reddit Comments

[u/WinterGrow]

Enlightening presentation that says the plow was the major contributor to the loss of topsoil.

[u/ArkGamer]

Haven't watched it yet, but thank you for sharing this!