Building Soil Biology in Low-Rainfall Farming

0:08 As Keith said, I'm from the Northeast corner of Colorado. We get 17 inches of annual rainfall and that comes in the form of snow and rain. Most of our soils are sandy loam or silt loam soils, and I currently farm 1900 acres and it's all crop share with various different landlords.

0:34 I'll tell you a little about my journey. I grew up on the farm doing wheat, summer fallow, tillage out there on the tractor, many hours killing weeds all summer long. And then I went off to the University of Nebraska to study economics, and at that time my dad was starting to transition to no-till. But like many people, we didn't know why we were doing it. Just everyone else was doing it and it seemed like a good thing to.

1:03 But as I came back I started running my own figures as I started farming other land and realized that a lot of money was being spent on inputs and a lot of those inputs weren't seeing a lot of rewards such as herbicides and fertilizer just getting so much money tied up into them and especially summerow you have so much money tied up in that before you even plant the crop. You have to have so many bushels per just to recoup that cost so that's kind of how I found the soil health movement or how it found me. I started investigating other ways to get rid of that.

1:40 And then about four years ago probably I went to a similar conference and when I seen that rainfall simulator when I seen them turn over the pan of tilled soil and there's no water in it that just changed everything for me because in a low rainfall area what's one of the most limiting factors it's your rainfall and if it's not going in your field.

2:01 You're shooting yourself in the foot already. So I started with cover crops in 2013 just 20 acres, and when I seen the results with that little test plot I started researching and finding as much information about it as I could. And once I felt comfortable with the amount of knowledge I learned, the next year the half the farm went to cover crops, and then the year after that the whole farm was cover crops, and some of the fields that had double or triple cover crops on them.

2:33 I used to be locked into rotation. You know, I had to have wheat here and then corn, fallow that, or millet, fallow that, and then you summer fallow. That's what I did every year. I was set on that, but since I've learned everything in these past few years I've gone to an adaptive rotation system where it depends what that field needs, it depends what the weather's doing.

2:57 Variety of factors. I don't ever lock myself into anything because I like to be able to change that in an instant if I need to. Right now I got wheat growing, I have rye growing, and then all the other acres have diverse cover crops on them—all over wintering cover crops. But my main goal is to have a root growing in that soil, something photosynthesizing, releasing root exudates the whole year.

3:24 Some of the things I found with doing these cover crops and planting after crops is I'm trying to bridge that gap between when wheat's drying down and you're waiting to harvest it and the time you get that cover crop in there. There's a window there where you're not photosynthesizing, you're not releasing any root exudates, and I'm trying to bridge that gap putting companions or something in there so I can prolong that photosynthesizing period.

3:56 Allan gave you the PhD version.

4:00 Of the soil food web I'll give you the farmer version. How many of you people have seen this in the NRCS office, the soil food web? And I never really understood it till this past summer after the conferences last winter. I dedicated myself to understanding what knowledge is out there from a lot smarter people than me to know what microbes, what microbes were they talking about? We always generalize and talk about the whole community, but what does each one of those specific organisms do?

4:35 So the soil food web, you know, you got the sun giving the energy to the plants and then in return the plants are giving energy back to all the organisms in the soil. There's bacteria, there's fungus, there's protozoa, there's nematodes, there's microarthropods, there's earthworms, and then there's your higher order predators, and it all starts with.

4:59 The sun in the plant and if you don't have transferring that energy into the soil you're not providing any food for those microorganisms. Bacteria are kind of the first order of organisms in the soil and then you got your fungus behind that and the nematodes always get a bad reputation because they're root feeding nematodes right. Well they're up there on the top of the food chain going directly to the roots and from what I've learned the root feeding nematodes and your anaerobic bacterias and your ciliate protozoas are kind of a sign that you have an unhealthy soil. It's because your soil is gone anaerobic—you don't have oxygen in that soil and all. If you can get the good organisms in that soil, if you can get a good aerobic soil you can start pushing out diseases and you start building that healthy.

5:58 Ecosystem. And why is that soil structure important? You know, healthy soil structure—that cottage cheese-like structure with all these passages—allows for good air flow, good movement, and good water infiltration. And it's a lot easier for plant roots or mycorrhizae or fungal networks to go in and get out and get those nutrients and transport them back to the plant.

6:25 And I often thought that I always question who actually builds soil structure. Is it the plant roots or what is it? But from what I've learned, it's actually the bacteria excreting glues, and those glues start holding smaller particles together. They start grabbing organic matter and decaying roots and sand, silt, clay, organic particles, and they start gluing those together. And then if you got fungus in there, they can start grabbing those other smaller particles at the back.

7:58 Table up in the right shows the carbon and nitrogen ratios of a bacteria and a protozoa. Protozoa feed on those bacteria, and when they feed on those bacteria they release those nutrients into a soluble form. The ratio for bacteria is 5 to 1, and the ratio for protozoa is 30 to 1. So 5 goes into 36 times. The protozoa have to eat 6 bacteria to get their carbon, but they only need one nitrogen so they have 5 left over so they release that.

8:31 What I found and what Dr. Williams was talking about earlier is a bacterial dominated soil. The way we've been farming we lack that nutrient cycling. We lack the protozoa. Just by looking at my own fields, I've seen exactly that. I have zero protozoa in my fields and they're all highly bacterial dominated.

8:56 Who's going to feed that soil food web? Mother Nature's always trying to feed it because she's growing weed, she's growing.

9:03 Anything, something's always popping up out there, but as producers and land owners we can feed that soil food web by having a plant growing and having diverse plants growing so that we're releasing different root exudates and different food sources to our biology and the soil.

9:30 This is kind of a picture talking about ecological succession. Mother Nature kind of tends to gravitate everything to a forest. It might take a couple hundred or thousand years depending on where you're at, but as time passes that tends to go to the far right of that diagram. And to the far left you got bare dirt or you got annual weed, something that wants to grow fast and put all its production into seed. And if you look at these things, the far left is a very highly bacterial.

10:07 Dominated soil and I don't call it soil. I guess it'd be called dirt because there's not the living soil food web is not in that far left spectrum so it's more functioning like dirt instead of soil. It's just a growing medium, but as you move along that progression, you start changing and if you kind of get right in the middle where we kind of want to be, you got, you know, half fungus and half bacteria. We're not growing trees so we don't want to get to the other far end of the spectrum.

10:40 Steve mentioned it a little earlier this morning, you know, what's a tool we could use? This isn't fancy like the one at the Noble Foundation. This is just a 300 or 400 dollar microscope, but what I've been doing is taking soil samples and looking at the organisms that are in my field. And on the far left there is a sample from my field and all them very teeny little dots are just bacteria, and it's the same story across.

11:14 Most of my fields, that's all there is, it's strictly bacteria. As you go to the middle there, you can see that long strand in the middle, that's a fungus strand. And keep that, that's in some compost, but that is one drop under that microscope diluted with 10 parts of water. So that's just a little speckle, that's just one drop and you can see that much activity going in there.

11:44 So I'm trying to give you the where my head's at, why I'm doing this, and I'll show you a little later what I'm doing, but I'm trying to get that soil food web back functioning so that I can start reducing all these other inputs and start making my soil function like it's supposed to.

12:04 You know, how does tillage upset all these things? I talked about it, it destroys any of that stability that those organisms built, any of those aggregates that were glued together. Anytime you take a tillage tool through there, you just explode all those aggregates, and that's not going to allow water to infiltrate. And you also decrease how much water you can even hold in that soil. Your soil bulk density increases, and you can imagine what happens to that soil biology, that's that.