2023 Eastern Nebraska Soil Health Conference - Marshall McDaniel

Deloris Pittman & Mike Kamm Author

03/20/2023 Added

26 Plays

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2023 Eastern Nebraska Soil Health Conference - Benefits of re-diversifying crop rotations in the Midwest - Marshall McDaniel, Iowa State University

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[00:00:05.370]Good morning everybody. So I crossed over the river.
[00:00:08.426]I heard one good morning. Good morning, everybody.
[00:00:11.640]Okay, that's better.
[00:00:12.630]I teach a soil fertility course, believe it or not,
[00:00:15.668]at 7:45 AM and it's like pulling teeth
[00:00:19.650]getting people to say good morning at that time.
[00:00:23.280]I'm really pleased to be here and I'm doubly honored.
[00:00:25.980]I knew Caro when she was a graduate student at Iowa State,
[00:00:29.394]and I've been at Iowa State for about seven years.
[00:00:32.880]I was born in Omaha so I kind of feel like
[00:00:34.830]I'm coming back home a little bit.
[00:00:37.140]But I'm gonna talk today about some research
[00:00:39.540]we've done over the past 20 years
[00:00:41.760]from this long-term experiment pictured behind me.
[00:00:44.310]Let's see if I've got the clicker here.
[00:00:47.610]A little bit of background about me before I do that.
[00:00:50.659]As I mentioned, I teach a soil fertility course,
[00:00:53.850]but my specialty is in soil fertility and soil health.
[00:00:57.450]I'm kind of a jack of all trades when it comes to soils.
[00:01:00.360]I also dabble in soil physics a little bit.
[00:01:03.720]You'll see some data that will support that.
[00:01:07.440]But I couch everything our lab does
[00:01:11.682]in the context of soil health.
[00:01:13.779]And I'm a little bit biased,
[00:01:16.350]but I'd rather Iowa State become
[00:01:18.060]the Mayo Clinic of Soil Health,
[00:01:20.220]but I'm happy to talk about it, everybody.
[00:01:22.620]I hope the Midwest becomes the Mayo Clinic of Soil Health.
[00:01:26.520]So, does anybody recognize,
[00:01:28.170]hopefully you recognize that crop on the right.
[00:01:30.570]Does anybody recognize the crop on the left?
[00:01:33.660]Sorry, I'm in a couple folks' way here.
[00:01:38.640]Alfalfa. Yeah.
[00:01:40.830]So I'm gonna talk about alfalfa being one crop
[00:01:44.227]that we no longer have in rotations. It's not as common.
[00:01:48.810]And I'll talk about some of the benefits
[00:01:50.970]we might be missing out on that.
[00:01:53.340]But before I do that, I want to thank a few people.
[00:01:55.696]Matt Liebman, he's now a retired professor emeritus.
[00:01:59.070]He's the one who originally established
[00:02:01.650]this long-term experiment I'm gonna talk about.
[00:02:04.110]He's pictured there in the bottom right,
[00:02:06.300]and he's had several grad students come through his lab
[00:02:09.660]and post-docs that have worked on this experiment.
[00:02:12.180]And I'll show you how many publications and findings
[00:02:14.820]we've gotten from this and I'm happy to talk more
[00:02:16.931]after I present our results.
[00:02:19.800]And also, Matt Woods,
[00:02:20.850]the guy looking very happy there with the guitar
[00:02:23.310]next to the John Deere.
[00:02:24.977]He's the one who actually does all the stuff
[00:02:27.300]and makes everything happen on the ground,
[00:02:28.920]the farm manager, makes the experiment happen.
[00:02:32.490]And then a couple of my students that collected the data
[00:02:34.586]and our funders, Iowa Soybean Association,
[00:02:38.610]just funded a new extension of this experiment
[00:02:42.270]that I'll explain in more detail at the end of my talk.
[00:02:45.600]Okay, so a little outline before we get started.
[00:02:48.420]Oh wait, if I don't get to your questions today,
[00:02:51.600]my email is there on the bottom right, marsh@iastate.edu.
[00:02:57.120]And speaking of Twitter again,
[00:02:59.460]you can follow all the cool stuff that folks in my lab do.
[00:03:02.760]I really just try to get out of the way,
[00:03:04.530]but @Soil_Plant_IXNS, which is short for Interactions.
[00:03:11.760]Okay so I'll talk about a little
[00:03:13.020]about info and background of Marsden
[00:03:15.510]and just where we're at with diversification.
[00:03:18.270]I'll go over some comprehensive soil health assessment
[00:03:20.970]that my students have done,
[00:03:23.640]hopefully convincing you the benefits of diversified
[00:03:26.460]rotations when it comes to soil health.
[00:03:28.920]Then we'll take a holistic look
[00:03:30.930]at sustainability of the system,
[00:03:32.430]including the agronomics production and other aspects.
[00:03:36.524]I'm gonna share with you some very new things.
[00:03:39.570]We haven't even started collecting data on it yet,
[00:03:41.809]kind of what I've been calling Marsden 2.0
[00:03:44.651]as I've taken over this long-term experiment.
[00:03:48.270]And then just conclude and then happy
[00:03:50.520]to take some questions and discuss.
[00:03:53.760]Okay, I have to poke you Huskers again.
[00:03:57.570]As Iowa farms, so farms the nation.
[00:03:59.640]I think there's, maybe you could plug Nebraska in there too.
[00:04:02.566]But this is a graph showing from the 1860s to today,
[00:04:08.632]corn and soy in the solid line that's orange,
[00:04:12.755]small grains, which is the dashed maroon line,
[00:04:16.890]and then hay, which is green.
[00:04:19.080]And what do you see around the 1950s or 1960s?
[00:04:26.310]Yeah, small grains are gone.
[00:04:28.440]Corn and soybeans now we're at like 95% of Iowa crop land.
[00:04:34.740]There's many reasons for this.
[00:04:36.858]Some of them are political market based. So economics.
[00:04:41.204]One of my colleagues at Iowa State thinks
[00:04:43.726]the real reason for this is the tractor, right?
[00:04:47.310]Because once we've got wider use of automated tractors,
[00:04:52.574]we don't need livestock on the farm.
[00:04:54.840]So you don't need the hay or the small
[00:04:56.970]grains as much to feed the animals.
[00:05:01.350]I already mentioned the other factors,
[00:05:03.948]but what I'm hopefully gonna answer
[00:05:06.180]and we can discuss a little bit about
[00:05:08.190]is what might we be missing out on
[00:05:10.956]with what's called grandpa's rotation.
[00:05:14.310]So I'm gonna pick on Will 'cause we
[00:05:15.840]talked about this last night.
[00:05:17.550]So he was talking about his grandfather that farms in Iowa
[00:05:20.412]and he misses the animals on the farm,
[00:05:24.534]but also at the same time, kind of glad not to do them.
[00:05:27.630]And Will's easy to pick out
[00:05:29.760]'cause he's probably one of the tallest
[00:05:30.930]guys in the audience and probably the longest hair too.
[00:05:34.920]But I think Will's very common story to many farmers
[00:05:38.700]is that this was grandpa's rotation, right?
[00:05:41.370]There's not a lot of folks that do this anymore.
[00:05:43.290]And most people or most farmers in Iowa
[00:05:46.590]are doing corn soybean rotation.
[00:05:48.881]And we do corn soybean rotation very well, right?
[00:05:52.006]Both Nebraska and Iowa.
[00:05:54.888]Iowa, we do it better, but we'll save that for another day.
[00:06:00.630]But it has come at a cost,
[00:06:02.931]and I don't mean to be all doom and gloom here,
[00:06:04.902]but this is a part of the, I think,
[00:06:06.810]regenerative ag movement, soil health movement.
[00:06:09.510]We started to recognize that we could do better.
[00:06:13.600]There's something called progress bias.
[00:06:17.309]There are a lot of biases that humans have,
[00:06:19.740]but I think we're all prone to progress bias,
[00:06:22.383]bias is the act of overstating or overvaluing the positive
[00:06:25.162]actions while downplaying our negative ones.
[00:06:27.690]The positive actions, obviously high corn,
[00:06:30.960]soybean productivity,
[00:06:32.730]and these might be some of the negative ones.
[00:06:35.520]So a wicked problem is a intractable problem
[00:06:38.400]or a problem that's very difficult to solve, right?
[00:06:40.350]Soil erosion.
[00:06:41.730]So I was picking on you all, Iowa being number one in corn,
[00:06:44.898]but Iowa is also number one in erosion.
[00:06:47.541]That's one of our major exports is soils
[00:06:51.559]and loss of wildlife habitat.
[00:06:54.990]Those of you like to hunt or fish,
[00:06:57.470]this might be something you care about.
[00:07:00.000]We've got local, regional and water quality issues,
[00:07:03.236]greater than 50% decline in soil organic matter.
[00:07:07.160]This has been documented by,
[00:07:09.004]I'll come back to that in a second.
[00:07:10.950]But there's a lot of science behind that.
[00:07:13.290]And then some of the socioeconomics.
[00:07:15.840]Farm consolidation, shrinking profit margins,
[00:07:18.654]farmer wellbeing being on the decline.
[00:07:21.270]And there are some solutions.
[00:07:23.493]These are not all the solutions,
[00:07:25.100]but there are some solutions to these
[00:07:26.250]that are what are sometimes called
[00:07:27.990]soil health promoting practices.
[00:07:31.040]No tillage, cover crops, diversified perennial rotations,
[00:07:34.890]restoring habitat of maybe unproductive landscapes.
[00:07:39.390]We have a pretty popular project in Iowa
[00:07:42.683]called the Prairie Strips Project.
[00:07:44.790]That kind of covers that one a little bit,
[00:07:46.827]the the loss of wildlife habitat
[00:07:48.848]while also being able to produce crops.
[00:07:51.731]And as I said I'm not going to talk
[00:07:55.014]about all these problems.
[00:07:57.180]I only have a about 40 minutes with you all.
[00:08:00.060]But I do wanna to really hone in on
[00:08:02.190]this 50% decline in soil organic matter.
[00:08:05.520]And this is, I think, part of the crux of why
[00:08:09.148]our soils don't function like they used
[00:08:11.730]to or they could in the future, right?
[00:08:13.980]And so this is an arbitrary timeline
[00:08:17.916]to the left and then kind of hypothetical
[00:08:21.119]based on real data to the right of that zero.
[00:08:24.630]And it's prior to EA means Euro-American cultivation, right?
[00:08:28.680]So about in Iowa where Ames is,
[00:08:32.450]about 15 to 17,000 years ago,
[00:08:35.790]the Wisconsin glacier retreated.
[00:08:38.260]This is where the Des Moines lobe is.
[00:08:40.680]And that's our parent material
[00:08:43.470]and this is a landform region in north central Iowa.
[00:08:47.280]That glacier started to recede,
[00:08:49.549]our rich productive soils started developing
[00:08:52.112]over those thousands and thousands of years.
[00:08:54.810]There were also native folks farming for three
[00:08:57.150]to 4,000 years before Euro-American cultivation.
[00:09:00.540]And they mostly farmed in riverbeds and along streams
[00:09:04.710]and these are archeological sites
[00:09:06.390]where they found maize and corn.
[00:09:08.910]I'm not here to talk about that,
[00:09:10.140]but we do know that we don't have a lot
[00:09:13.200]of information on their agronomic impacts on the land,
[00:09:16.950]but we can safely say that their impact
[00:09:19.879]was not as great as when Euro-American
[00:09:23.190]cultivation began, right?
[00:09:24.837]And so we see this decline. This is hypothetical.
[00:09:28.320]It might not be kind of an exponential decline.
[00:09:31.050]It might be linear,
[00:09:32.550]but we get a loss of soil organic matter,
[00:09:35.430]loss of soil ecosystem services.
[00:09:37.740]I'll come back to what that term is.
[00:09:39.960]And then we're here at present day, right?
[00:09:42.600]With 50% of a glass that could be totally full.
[00:09:47.220]But I'm an optimist.
[00:09:48.360]I don't mean to be all doom and gloom here.
[00:09:50.730]I think we can improve, right?
[00:09:53.370]And still have productive landscapes.
[00:09:56.460]And so I call this a management intervention, right?
[00:09:59.220]So pick one of the soil health promoting practices
[00:10:02.060]I mentioned, there are other ones out there as well,
[00:10:04.272]and then we can regenerate increased soil organic matter
[00:10:08.025]and also restore some of those soil ecosystem services.
[00:10:11.670]And that's really what the soil health movement
[00:10:15.480]and regenerative agriculture is all about, right?
[00:10:17.550]Some of these buzzwords we've heard and monitoring it.
[00:10:21.330]So as a scientist, stakeholders, carbon markets,
[00:10:24.722]even farmers are wanting to know
[00:10:27.364]the rate of improvement, right?
[00:10:29.850]Are we at this level or are we at this level?
[00:10:33.750]Or maybe even this level, right? This rate of increase.
[00:10:39.060]But soils change slowly and sometimes
[00:10:41.100]you might not see any change at all.
[00:10:42.570]We see that with some soils in Iowa.
[00:10:45.600]Even this experiment I'm gonna talk to you about now,
[00:10:47.910]it's taken a long time to see changes in soil carbon,
[00:10:51.330]but there are some other changes
[00:10:53.040]that we've observed that I'll show you in a moment.
[00:10:55.950]So this is, I always use this, I use this in my class,
[00:10:59.310]I use this when I come to extension events like these.
[00:11:01.980]This is a diagram from the Food
[00:11:03.930]and Agriculture Organization of the UN.
[00:11:06.810]These are the soil functions.
[00:11:08.670]You could also call it soil ecosystem services.
[00:11:11.730]And soil health is really how well these are performed.
[00:11:15.240]And in particular,
[00:11:16.770]these ones that I've outlined and read
[00:11:19.020]that are centered around the hubcap of soil organic matter,
[00:11:23.430]and I'll just walk you through a few of these.
[00:11:25.440]So the one on the far left is the prime directive
[00:11:28.464]of agriculture for all you Trekkies out there.
[00:11:32.010]Provisioning of food, fiber, and fuel, right?
[00:11:34.830]That's kind of the primary purpose of agriculture.
[00:11:37.740]But there are other ones that are gaining traction.
[00:11:39.720]So, carbon sequestration, right?
[00:11:42.870]We've all heard the buzz around carbon markets.
[00:11:44.910]That's just another soil ecosystem service
[00:11:47.010]or what soils do to benefit humans
[00:11:49.444]and other life on planet Earth.
[00:11:51.660]Water purification, climate regulation, nutrient cycling,
[00:11:55.920]habitat for organisms, flood regulation.
[00:11:58.950]That's a real key critical one.
[00:12:01.140]We've had some major floods in Iowa
[00:12:02.856]in the Cedar Rapids area in the past several years.
[00:12:08.070]And the way to do that and restore some
[00:12:12.030]of those soil ecosystem services are quite simple.
[00:12:15.630]You can boil it down to five soil health principles
[00:12:18.750]that I always borrow from the NRCS.
[00:12:20.580]I mean, I make it seem simple,
[00:12:21.930]but there are five soil health principles,
[00:12:25.620]soil armor, minimize disturbance,
[00:12:28.860]plant diversity, continual live plant root.
[00:12:31.590]I'd sometimes refer to it as perenniality.
[00:12:34.230]And then livestock integration.
[00:12:36.960]And then I'm just gonna list a few practices
[00:12:39.330]that fall under each one of these, right?
[00:12:40.980]Cover crops, perennial crops, residue, reduced tillage,
[00:12:44.430]CRP or prairie strips, minimize disturbance,
[00:12:48.780]reducing tillage,
[00:12:50.760]lower compaction through controlled traffic farming.
[00:12:55.290]Now with precision guided equipment,
[00:12:57.090]you can really minimize disturbance or at least restrict
[00:13:00.000]it to certain portions of the field.
[00:13:02.760]Plant diversity, cover crop mixtures, crop rotations,
[00:13:05.431]like we'll be talking about today,
[00:13:07.592]intercropping, CRP and prairie strip.
[00:13:11.490]You could see a lot of these cover
[00:13:12.780]more than one principle, right?
[00:13:15.480]Cover crops are one of the best ways to extend
[00:13:19.342]the duration of that living live plant route,
[00:13:22.709]perennial crops, I'll show an example of a perennial crop
[00:13:25.650]today that we do some work on.
[00:13:27.390]Relay cropping, CRP and prairie strips of course.
[00:13:31.140]And then livestock integration, grazing cover crops.
[00:13:34.770]I've seen some cattle on I-80
[00:13:36.873]when I was driving west out here.
[00:13:39.600]I saw some on the way up here this morning as well
[00:13:42.690]out in the corn stover.
[00:13:46.110]Seeding pastures to rotation,
[00:13:48.210]even adding manure as kind of an indirect form
[00:13:50.940]of livestock integration rather than
[00:13:53.310]using synthetic fertilizer or substituting some,
[00:13:56.700]and diversified perennial rotations
[00:13:58.710]covered many of these principles.
[00:14:00.879]Grandpa's rotation did. Right?
[00:14:02.520]And I just highlighted which ones,
[00:14:04.980]maybe the only one that minimized disturbance.
[00:14:08.010]But usually in extended rotations
[00:14:10.329]tillage intensity goes down as well.
[00:14:14.640]Okay so a big part of our problem
[00:14:17.280]is that we have soils that are bare for 50% of the year.
[00:14:21.810]And bear with me here,
[00:14:23.391]I'm trying this slide out on a few audiences.
[00:14:26.761]It's kind of a strange way to think of time,
[00:14:29.940]but think of the year as a clock with January at noon
[00:14:33.352]and then February, March, April, may, June, July, et cetera.
[00:14:37.534]And this is what our business as usual
[00:14:40.533]or two year rotation is, right?
[00:14:42.960]That little thin, skinny brown line
[00:14:45.870]is when our soils are bare most of the time,
[00:14:48.750]or at least don't have a living root in it.
[00:14:51.030]Might have some residue if you're doing reduced tillage.
[00:14:55.116]And this is what happens.
[00:14:57.660]So this is a picture my postdoc
[00:14:59.670]pictured in the bottom right there,
[00:15:02.430]took a picture just a few weeks ago in January.
[00:15:06.390]He was out working on mid-January day
[00:15:09.712]and what you see in the background
[00:15:13.082]is a crop we call Miscanthus short.
[00:15:15.990]That's its genus species name.
[00:15:18.720]But there's a couple things I want to point out here.
[00:15:21.000]One, that perennial crop, it's a biomass crop, Miscanthus.
[00:15:25.440]It's harvested in late winter, early spring.
[00:15:29.730]It's still standing there.
[00:15:31.281]It's protecting the soil under it.
[00:15:33.600]It happens to be highly productive.
[00:15:37.920]It's holding the soil and stabilizing the soil underneath.
[00:15:40.950]It's efficient with cycling nitrogen,
[00:15:44.730]but it's also catching our neighbor's soil.
[00:15:47.820]That's our neighbor's soil that's doing corn bean rotation
[00:15:51.084]and it's just blown up against a snowbank there.
[00:15:55.110]And then the picture on the right is showing,
[00:15:57.330]he tried to dig down to see how deep that layer
[00:16:00.090]of our neighbor's soil is on the snowbank.
[00:16:03.169]So there's quite, I mean,
[00:16:04.950]this isn't like the pictures from the Dust Bowl
[00:16:07.950]where there are cars. There's a famous picture.
[00:16:10.530]You all can probably visualize it when I mention it
[00:16:12.869]from somewhere in South Dakota, but there's an old car,
[00:16:16.740]a Model T or something that's almost
[00:16:18.990]completely buried by soil.
[00:16:21.030]So this problem is still out there,
[00:16:22.590]even though we don't see it like we did in the Dust Bowl,
[00:16:25.525]but rejuvenating soil health will help prevent it, right?
[00:16:33.540]One way to do that is using cereal rye.
[00:16:36.930]So now coming back to this kind of clock here,
[00:16:41.047]now we've got rye kind of growing maybe in the shoulder
[00:16:44.213]seasons and then dormant rye here. Can I move this?
[00:16:50.643]This thing's kind of getting in the way. Yeah, there we go.
[00:16:55.740]And there's other ways to kind of fill
[00:16:58.587]that skinny brown bar that we have bare soil on, right?
[00:17:03.510]So now we've got a corn soybean rotation,
[00:17:06.450]but we could do longer rotations.
[00:17:07.950]We can have a small grain that over winters
[00:17:10.908]and goes dormant and then we can use
[00:17:14.670]red clover or oat in this case,
[00:17:19.865]or we could do oat as a companion crop
[00:17:23.370]and alfalfa and cover that next year.
[00:17:25.530]So those two years below are coming in
[00:17:28.260]out of the clock in the next way.
[00:17:30.780]I know it's kind of a weird way to look at time
[00:17:32.850]or at least time over a year,
[00:17:35.902]but that's the big problem we have.
[00:17:39.270]And so this was in part the reason why my colleague
[00:17:42.750]Matt Liebman developed this experiment.
[00:17:44.610]He's a weed ecologist,
[00:17:45.750]so he was more interested in the weed dynamics.
[00:17:48.544]But I've been working with him on
[00:17:50.550]some of the soil health aspects.
[00:17:53.070]And this is a Marsden Agroecosystem
[00:17:56.130]Diversification Experiment.
[00:17:57.480]There are three cropping systems.
[00:17:58.800]I'll explain in a moment. This is an aerial view.
[00:18:01.470]One of the benefits of this experiment,
[00:18:04.320]besides being long-term, it's now over 21 years,
[00:18:07.359]is that it has every phase of the crop rotation in it.
[00:18:11.106]So that's why you see more than three plots
[00:18:13.700]in each of the replicated blocks,
[00:18:15.690]which are those rectangles that are attached to each other.
[00:18:19.620]Is initiated in 2001 by Matt there
[00:18:22.010]in the bottom corner, now retired.
[00:18:24.754]And one of the reasons why I really like working on this
[00:18:27.480]experiment is that we work with farmers
[00:18:30.925]on tweaking it and presenting the results.
[00:18:35.550]Here's a picture of Matt talking to some farmers
[00:18:39.120]at a Practical Farmers of Iowa event
[00:18:40.773]actually at the site in 2003 just
[00:18:43.860]shortly after it's established.
[00:18:46.080]And the ethos is a long-term investigation or the goal.
[00:18:51.030]This is more of a goal, I guess,
[00:18:52.650]how cropping system diversification and livestock
[00:18:55.170]integration affects sustainability.
[00:18:57.540]I would add soil health to that as well.
[00:18:59.940]And then to conduct research
[00:19:01.500]that's relevant to Iowa farmers.
[00:19:03.120]This means talking, engaging,
[00:19:04.950]listening to farmers about the practices we're doing,
[00:19:07.890]the practices they're doing,
[00:19:10.200]how we can learn from each other,
[00:19:11.593]use farmer's input to inform the research.
[00:19:13.410]And this makes the research, at least to me and Matt,
[00:19:15.750]more meaningful and impactful.
[00:19:19.890]And I like to say that Marsden is probably one
[00:19:22.050]of the most sampled 16 acres of land in Iowa.
[00:19:29.880]As I mentioned, we've had a 21 year and going crop record
[00:19:33.051]with crop data with each phase of the rotation represented,
[00:19:39.027]38 peer-reviewed publications from data from Marsden
[00:19:44.220]and this includes entomologists, weed ecologists,
[00:19:47.902]economists, microbiologists, plant pathologists,
[00:19:52.669]food nutritionists and crop modelers,
[00:19:55.780]and millions in funding over the years,
[00:19:58.314]as I already acknowledge the funding sources,
[00:20:01.590]Iowa Soybean, USDA, NSF,
[00:20:03.783]Iowa Nutrient Research Center and Walton Foundation.
[00:20:07.512]Here's a little bit about those
[00:20:10.064]rotations I mentioned I'd come back to.
[00:20:11.904]So here's the two year rotation business as usual.
[00:20:14.550]Corn, soybean, all the nutrients are synthetic.
[00:20:19.140]Here's the three year rotation, corn, soybean,
[00:20:21.840]but oat, then red clover,
[00:20:24.775]and the majority of the nutrients
[00:20:27.120]come from composted cattle manure.
[00:20:29.215]But we supplement based on,
[00:20:31.244]I think you all maybe call it PSNT out here,
[00:20:34.740]but late spring nitrate tests
[00:20:36.720]if we're deficient in the corn year,
[00:20:38.678]we'll add according to our local fertility guidelines.
[00:20:43.140]I'm not gonna talk about that three year rotation very much.
[00:20:45.450]We're just gonna compare the four year
[00:20:46.980]and two year with the rest of the talk.
[00:20:49.800]And that four year is corn, soybean, oats,
[00:20:52.735]and then alfalfa for about a year and a half.
[00:20:57.510]And that includes for up to, depending on the weather,
[00:21:00.090]two or maybe four or five even cuttings of hay.
[00:21:06.120]And most of the nutrients come from composted cattle manure.
[00:21:11.910]Okay, I'm gonna take a little break.
[00:21:14.070]And while you all admire this closeup photo of soil,
[00:21:18.330]that's soil from under a prairie,
[00:21:19.830]lots of roots there, stable aggregates.
[00:21:23.310]So in 2017,
[00:21:24.840]this was 15 years after the establishment of the experiment,
[00:21:27.912]my former graduate student now farm planner
[00:21:31.380]at Mad Agriculture in Colorado, and former postdoc,
[00:21:34.946]now assistant professor in biology at Minnesota State,
[00:21:39.690]they went out and sampled.
[00:21:40.800]So all the data you're gonna see are thanks to them.
[00:21:44.850]This is a very complex graph.
[00:21:46.590]Let me walk you through it and then I'm just
[00:21:48.330]gonna hit a few of the highlights.
[00:21:50.280]So each of the colored kind of outer bars are physical,
[00:21:53.959]biological, and physical aspects
[00:21:59.105]of soil health that we measured.
[00:22:01.440]Some of them are abbreviated,
[00:22:02.940]so you can't tell what they are.
[00:22:04.620]But the closer the line is to the outside
[00:22:07.470]of it is the more healthy the soil is.
[00:22:09.900]And then the area around that line
[00:22:11.520]is kind of the error or variance.
[00:22:14.809]And the thing that's striking is that the blue line,
[00:22:19.019]which is the two year rotation,
[00:22:21.367]almost exceeds the two year in every category.
[00:22:27.647]I only have time to hit a few of the highlights.
[00:22:30.810]So I'm gonna talk about soil water under it, soil hardness,
[00:22:34.830]we measured with penetrometer, soil microbial biomass.
[00:22:40.080]Those are very critical for many soil ecosystem services.
[00:22:45.120]I'll go over some earth worms,
[00:22:46.860]everybody's favorite charismatic megafauna in the soil.
[00:22:52.650]And I'll talk a little bit about nitrogen as well.
[00:22:56.217]We've got some cool results with the nitrogen.
[00:22:59.550]Okay, so first let's look at the water.
[00:23:01.440]So this is just in the top six inches of the soil
[00:23:03.832]and these are three years of the rotation.
[00:23:07.891]2017, 2018, 2019.
[00:23:10.620]The first two years the plots were in the same crop,
[00:23:14.460]but then the third year the four year
[00:23:17.730]rotation went to oat alfalfa.
[00:23:20.310]And what we saw is that the longer rotation was wetter.
[00:23:24.632]And you know, in Iowa, to admit, you know,
[00:23:28.350]we usually have a problem of too much water,
[00:23:30.420]especially in the spring.
[00:23:31.890]But for folks out here in Nebraska, especially west,
[00:23:35.108]I know you irrigate more and having that water,
[00:23:38.731]that extra water in the soil, can be very beneficial.
[00:23:42.750]And it's beneficial in Iowa too
[00:23:44.430]later in the growing season when things are drier,
[00:23:47.670]you know, say July, late July, August,
[00:23:50.883]but almost across the entire rotation,
[00:23:55.916]at least from these three years,
[00:23:59.820]the gravimetric water content is greater
[00:24:02.408]in the four year rotation.
[00:24:04.230]I'm gonna come back to that because there's some
[00:24:06.510]new work we're doing that I'm gonna highlight about that.
[00:24:12.330]I mentioned we measured pen root penetration.
[00:24:15.480]So this is directly related to provisioning
[00:24:17.730]plant growth, right?
[00:24:18.870]The harder your soil is the more difficult root
[00:24:21.183]will be to get through it and you
[00:24:23.910]usually don't get a good crop if you
[00:24:25.740]don't get a root through it easily.
[00:24:29.430]And so on the X axis or the bottom
[00:24:32.685]is pressure in kilopascals,
[00:24:35.640]and then on the Y axis you're looking at depth,
[00:24:39.210]and through the depth, so 40 centimeters,
[00:24:43.470]30 centimeters is a foot.
[00:24:46.350]So you can see we just went slightly below a foot,
[00:24:49.858]but down from zero to 30 centimeters,
[00:24:52.440]sorry for the metric units, down to a foot,
[00:24:55.230]the four year rotation had much lower pressure
[00:24:59.257]compared to the two year or resistance
[00:25:02.010]to root growth, right? So that's a good thing.
[00:25:05.309]It might explain some of the yields data that
[00:25:08.370]I'll show you at the end here
[00:25:09.750]when we pull everything together.
[00:25:12.240]Okay, let's look at one of my favorite soil health metrics.
[00:25:15.780]These are microbes, microbial biomass.
[00:25:18.030]This is a measurement we do in our lab a lot.
[00:25:20.850]What we do is we take the knockout gas
[00:25:23.220]you see in movies, you know, chloroform rag,
[00:25:25.915]throw people in the back of the trunk.
[00:25:27.690]We actually use that to explode microbes,
[00:25:30.482]extract all their guts from the soil
[00:25:32.970]and then we could get how much biomass is in there.
[00:25:36.240]And this is showing microbial biomass
[00:25:38.813]over those same three years I showed the water, right?
[00:25:42.372]And measured multiple months.
[00:25:46.487]So in the corn year, higher consistently as well,
[00:25:52.680]microbial biomass, in the soybean year,
[00:25:55.740]even greater differences, right? Much larger differences.
[00:26:00.480]Then when we go in the four year to oat alfalfa,
[00:26:03.240]still higher microbial biomass. Very consistent increase.
[00:26:07.200]We see this actually at the six to 12 inches as well.
[00:26:11.190]And on average it's about 62% greater microbial biomass.
[00:26:15.780]And so those microbes are turning over,
[00:26:18.540]their cycling nutrients to plants,
[00:26:21.810]they're actually involved in long-term
[00:26:24.480]carbon stabilization as well.
[00:26:26.610]I won't go into the nitty gritty details on that,
[00:26:29.340]but they're very critical for soils.
[00:26:33.360]Another organism,
[00:26:34.650]these ones we could see with our naked eye.
[00:26:37.970]These are earth worms in the four year rotation
[00:26:39.900]compared to the two year, about 70 more earth worms.
[00:26:44.310]So my student went out there,
[00:26:45.810]dug little pits and measured the earth worms abundance.
[00:26:50.010]So this is just how many there are per meter cubed of soil.
[00:26:55.680]And we saw a lot more earth worms in the four year rotation,
[00:26:59.100]as is probably no surprise.
[00:27:02.395]I'm gonna skip this nitrogen stuff
[00:27:05.490]a little bit just to stay on time.
[00:27:08.190]I want to talk about some of the future Marsden,
[00:27:12.660]but I do wanna say 'cause I did mention microbes,
[00:27:15.900]more of the nitrogen, extractable nitrogen,
[00:27:18.870]so you all are probably most familiar
[00:27:21.338]with ammonium and nitrate,
[00:27:22.980]which are the plant available forms,
[00:27:24.930]but there are two other forms that are associated
[00:27:28.140]with carbon compounds or their organic molecules,
[00:27:31.320]salt extractable organic nitrogen.
[00:27:33.508]Raise your hand if you're familiar with the Haney test.
[00:27:37.590]So in the Haney test they have
[00:27:39.600]a water extractable organic carbon
[00:27:42.150]and water extractable organic nitrogen.
[00:27:44.100]That's kind of what this is
[00:27:45.900]and even though the total nitrogen is not significantly
[00:27:50.160]greater, it's on average greater.
[00:27:53.460]But even more importantly, in my opinion,
[00:27:55.980]is there's more nitrogen in those micro bodies
[00:27:58.896]and in the salt extractable organic nitrogen.
[00:28:01.740]If you just add up those two pools,
[00:28:04.230]it's greater than all of the extractable
[00:28:06.420]nitrogen in the two year.
[00:28:08.190]I think this is really feeding crops,
[00:28:11.310]corn and soybeans even, maybe later in the growing season.
[00:28:16.530]Okay, so returning to this complex graph here,
[00:28:20.250]I just want to go over a couple other highlights
[00:28:23.160]I don't have the time for.
[00:28:24.240]26% reduction in bulk density,
[00:28:26.670]16% increase in cation exchange capacity,
[00:28:29.934]kind of the size of the piggy bank for cation nutrients.
[00:28:33.780]10% increase in pH, which was a good thing.
[00:28:36.660]Closer to neutral.
[00:28:38.667]157% increase in that salt extractable carbon,
[00:28:42.960]that water extractable carbon from the Haney test.
[00:28:47.019]Now let's talk about kind of summing it up
[00:28:50.010]and talking about what it means.
[00:28:52.282]So there's a lot more nitrogen in the four year rotation,
[00:28:54.810]but what does that mean for water quality?
[00:28:57.060]Well, it turns out that that system
[00:28:58.860]is a lot more efficient with cycling nitrogen
[00:29:01.173]because we've got lysimeter.
[00:29:03.330]So lysimeters are a way we can suck water out
[00:29:06.150]at about four feet deep and we can look at the nitrogen
[00:29:10.986]that's in that water and the four year reduced nitrate
[00:29:15.550]at that four feet depth, seven out of nine years,
[00:29:20.516]that's kind of what these, each of these points show.
[00:29:23.670]If it's a purple line, that means it decreased it,
[00:29:26.561]the dashed gray is the only one where it increased it
[00:29:29.730]and on average it's a 9.8% decrease
[00:29:33.587]in the corn years of the rotation
[00:29:36.722]out of the kind of nine or 10 years
[00:29:38.490]we sampled the lysimeters.
[00:29:41.496]This is just as a reference.
[00:29:43.380]EPA standard for drinking water is at 10 parts per million.
[00:29:49.170]Just because it's at these levels in our soils, however,
[00:29:55.170]does not mean that's what ends up in the drinking water.
[00:29:57.330]There's a lot of things that could happen
[00:29:59.549]with that nitrogen before it gets to the stream.
[00:30:04.830]Soybeans,
[00:30:06.780]we saw greater reduction in nitrate
[00:30:09.601]with the four year rotation on the right,
[00:30:12.780]the blue there, reduced in six out of nine years.
[00:30:16.620]So pretty consistent decrease in nitrate leaching.
[00:30:20.790]So there's more efficient cycling.
[00:30:22.410]What that tells me is there's more efficient cycling
[00:30:25.620]in the corn and soybean years of that four year rotation.
[00:30:30.584]Okay, let's bring it all together. Corn yields.
[00:30:34.530]So many of you're probably wondering what those look like.
[00:30:37.200]They're significantly higher,
[00:30:39.900]but only about 5% if you look at the 20 year record.
[00:30:43.590]So 203 bushels versus 192.
[00:30:47.040]Soybean is really where you see your benefit.
[00:30:50.190]20% increase and some of this
[00:30:52.560]is actually due to disease suppression.
[00:30:54.630]So soybean cyst nematode is suppressed with this rotation.
[00:31:00.060]We've had some scientists demonstrate that.
[00:31:03.030]If you look at the whole rotation net profitability,
[00:31:07.080]it's a little bit higher, 6%,
[00:31:08.880]but not statistically significant when
[00:31:10.907]you compare it on a plot by plot basis.
[00:31:15.690]However, synthetic fertilizer that you're reducing,
[00:31:18.720]and this is kind of included in the profitability,
[00:31:21.510]you can reduce and especially this
[00:31:23.730]is based on older fertilizer prices,
[00:31:26.070]so that that actually net increase might go
[00:31:28.965]up with the higher fertilizer prices,
[00:31:30.360]although they're coming down a little bit.
[00:31:31.980]But 86% decrease in synthetic fertilizer use
[00:31:36.480]over the four year rotation, herbicide use goes down.
[00:31:40.200]Fossil fuel energy use goes down by 65%.
[00:31:44.488]The environmental impact,
[00:31:46.020]I already mentioned that if we look at that nitrate
[00:31:48.930]in the soil water it's a 22% decrease.
[00:31:53.820]And some collaborators have measured soil erosion
[00:31:57.356]and showed that, or not measured it,
[00:32:00.570]but did a modeling study where they can use
[00:32:04.020]computer models and showed that it was decreased by 62%.
[00:32:10.680]So pretty overwhelming benefits
[00:32:14.280]of grandpa's rotation, right?
[00:32:16.560]I think I just like hit you all with like a litany
[00:32:20.306]of all these benefits, right?
[00:32:22.080]And so it seems like we're missing out
[00:32:24.720]on a lot from grandpa's rotation.
[00:32:27.851]Okay, so I'm gonna pause there again.
[00:32:31.110]How much time do I have?
[00:32:34.890]Okay, nine more minutes. Great.
[00:32:40.680]Now I'm gonna talk a little bit about some benefits
[00:32:43.208]that you can't add up in those tables
[00:32:46.890]and put in these kind of economic analyses,
[00:32:49.440]and that's resilience to climate change.
[00:32:54.330]So in Iowa, I don't know about Nebraska,
[00:32:56.430]I haven't looked at the stats for Nebraska, but Iowa,
[00:32:58.882]our springs are getting wetter and our summer
[00:33:02.850]precipitation is getting more variables.
[00:33:04.530]So we might have more droughty years
[00:33:06.180]and more wet years as well.
[00:33:09.150]And then the second thing that I hear a lot
[00:33:11.940]of interest from farmers about,
[00:33:13.530]and particularly with the carbon markets,
[00:33:16.230]is this idea of additionality.
[00:33:17.760]Has anyone heard this term additionality before?
[00:33:20.160]Raise your hand if you have. Okay, a few folks have.
[00:33:24.570]So the idea, I like to call it stacking,
[00:33:27.420]but the carbon markets,
[00:33:28.899]some of the programs will pay for past
[00:33:32.564]practices up to maybe five years.
[00:33:35.713]But then, you know,
[00:33:37.274]some of them do not pay farmers for doing something
[00:33:41.577]they've already been doing or even adding
[00:33:44.970]another practice if they're already doing the right thing.
[00:33:47.400]So we're gonna test this at Marsden
[00:33:49.170]and I'll explain it more.
[00:33:51.750]We got some funding from Iowa Soybean,
[00:33:53.850]this is gonna sound crazy to you all out
[00:33:55.470]in Nebraska where you're trying to water your crops,
[00:33:58.110]but we're actually gonna drought our crops.
[00:33:59.970]We're gonna put these rain out shelters
[00:34:03.057]and this is showing corn here.
[00:34:06.240]And this was at Michigan State where Caro
[00:34:08.220]worked before she came here.
[00:34:09.900]So we got this idea and this
[00:34:11.867]is a picture from Michigan State,
[00:34:13.508]but we're gonna roll these same shelters out over
[00:34:15.270]the four year and the two year rotations
[00:34:18.512]and the soybean year and see if that extra
[00:34:22.020]water helps during a really droughty year.
[00:34:25.440]So we're intentionally imposing droughty year.
[00:34:28.001]The next research question is,
[00:34:30.123]what happens if we stack more soil health
[00:34:32.400]promoting practices and what I'm calling Marsden 2.0?
[00:34:36.990]And what I mean by that, I haven't told you all this,
[00:34:39.611]but we used a moldboard plow up
[00:34:42.495]until last year in the four year rotation.
[00:34:49.230]If you look at tillage intensity,
[00:34:51.581]it only gets a moldboard plow once,
[00:34:53.760]the two year rotation gets more
[00:34:55.950]frequent tillage with a disc.
[00:34:58.170]But we're doing two things in the future.
[00:35:00.810]One, we've already gone no-till,
[00:35:03.783]all the systems, two year and four year,
[00:35:06.065]and then we're also going to add cover crops
[00:35:07.500]in between the corn and the soybean year.
[00:35:09.720]We're starting with corn and soybean because we know
[00:35:12.000]there's not as much yield drag
[00:35:13.363]in between the corn and soybean.
[00:35:15.240]I'll explain that in a second.
[00:35:17.130]Okay. Springs are getting wetter in Iowa.
[00:35:19.680]I already mentioned that.
[00:35:21.810]Maybe a little bit wetter in Nebraska according to this map.
[00:35:24.600]This is from the National Climate Assessment.
[00:35:27.298]Here's data to support it. This is precipitation.
[00:35:30.220]The dots are the individual years. I'd look at the bars.
[00:35:33.810]Those are the five year average, and then the black,
[00:35:36.660]the dark black line is the average
[00:35:38.730]over the 100 year average
[00:35:41.117]and you can see our springs are getting wetter.
[00:35:45.753]So besides springs becoming wetter, as I mentioned,
[00:35:50.550]precipitation in the summer,
[00:35:52.110]which is the graph on the right, is getting more variables.
[00:35:54.930]So we might get a year like '93,
[00:35:57.270]I think that's 1993 is really wet,
[00:35:59.550]flood year in the Midwest, and then more years, like 2012,
[00:36:04.110]many of you I'm sure remember, very dry year in the Midwest.
[00:36:09.240]And so that's part of the climate aspect
[00:36:12.750]and if the four year rotation
[00:36:15.060]can add climate resilience. Right?
[00:36:17.760]And then the second part, the stacking,
[00:36:20.010]as I mentioned this is just hypothetical yield data.
[00:36:22.770]There's not even units on it,
[00:36:24.720]but let's say these are the four year
[00:36:26.280]and two year yields for corn,
[00:36:28.680]but what we're doing is now we've converted everything
[00:36:31.170]to no-till and we're gonna monitor
[00:36:33.570]the change in yield over time.
[00:36:36.150]You know, there's something called yield drag
[00:36:37.800]with no-till, in particular,
[00:36:40.620]in places like Iowa that soils can be sometimes too wet.
[00:36:44.010]So maybe we might see the two year decline
[00:36:47.640]and the four year stay the same. We don't know.
[00:36:50.940]That's something we're gonna be testing
[00:36:53.850]in the next few years that hopefully
[00:36:55.620]Caro can invite me back and I can
[00:36:57.930]tell you some of the results from that.
[00:36:59.670]And as I mentioned, we're gonna insert,
[00:37:03.570]so these are the two year, three year,
[00:37:05.880]four year rotation with kind of the crop phase,
[00:37:09.556]and we've got a split plot treatment.
[00:37:12.673]So we're splitting each of those plots
[00:37:14.040]and we're gonna insert cereal rye cover crop
[00:37:17.040]between the corn and soybean year to see
[00:37:20.760]what extra benefits we might see from stacking
[00:37:24.448]another practice, perenniality,
[00:37:26.550]on top of what we are already doing
[00:37:28.620]with the four year and three year rotations.
[00:37:33.030]Okay, to wrap things up.
[00:37:35.910]Humans are prone to progress bias, right?
[00:37:38.280]Corn and soybeans, we do it really well,
[00:37:40.530]but it's come at a cost.
[00:37:42.270]Hopefully I've convinced you it's cost
[00:37:44.438]and the benefit of doing things like grandpa's rotation
[00:37:48.429]that we might be missing out on.
[00:37:51.360]And so the idea is how do we capture both the benefits
[00:37:54.480]and high productivity with soil health?
[00:37:57.450]And I think we could do it.
[00:37:58.590]I'm optimistic. I think we can do it.
[00:38:02.760]Okay. Last thing I wanna plug.
[00:38:05.010]For anybody that knows soon to be finishing PhD students
[00:38:08.520]or postdocs looking for a job,
[00:38:11.160]we have a nitrogen fertility management or position
[00:38:14.607]at Iowa State that's open for the next couple weeks.
[00:38:18.346]If you wanna work with great folks,
[00:38:20.182]I'm not saying I'm one of them,
[00:38:21.960]but other folks at Iowa State and work on soil health
[00:38:27.060]and nitrogen fertilizer recommendations
[00:38:28.800]beyond email my department chair
[00:38:32.689]up there or talk to me about it.
[00:38:35.298]I could tell you more about the position
[00:38:37.469]and I want to end with this slide.
[00:38:39.119]This is a prairie strip inserted
[00:38:40.890]in between some glowing corn.
[00:38:43.170]This is one of my favorite photos of prairie strips,
[00:38:45.960]which is a soil health promoting practice as well.
[00:38:49.590]Thank you for your time everybody.
[00:38:50.880]I'm happy to take some questions.
[00:38:53.730]Hello?
[00:38:55.739]Yeah. Works, awesome.
[00:38:57.705]So there were two or three particular
[00:39:00.570]measurements that were better
[00:39:02.250]in the two year than the four year.
[00:39:04.528]I'm just curious what those could possibly be?
[00:39:06.693][Marshall McDaniel] Good eye.
[00:39:08.370]Oh yeah, so I don't need to repeat it, right?
[00:39:11.040]I think you had the microphone.
[00:39:12.450]Did everybody hear that?
[00:39:14.776][Marshall McDaniel] Okay, I will repeat it then.
[00:39:16.170]So this gentleman up here had a keen eye
[00:39:19.039]and he said there were two of those measurements
[00:39:21.600]or three even that the two year was actually higher.
[00:39:25.350]They were not significantly higher,
[00:39:27.570]but one of them was the CO2 burst test in the Haney.
[00:39:32.310]It was higher in the two year rather
[00:39:34.830]than the four year.
[00:39:37.800]Keen eye.
[00:39:40.200]There's another question in the back.
[00:39:42.187]Okay.
[00:39:44.799][Audience Member 2] In December,
[00:39:46.160]I was at the big soil health event in City Falls.
[00:39:49.650]There was a vendor there with biochar
[00:39:53.446]and he was saying when there's a new NCRS program
[00:39:57.060]coming out to help (indistinct) and biochar.
[00:40:00.498]However, when they contacted me,
[00:40:03.450]they say that it's not available in Iowa
[00:40:06.150]'cause ISU in their infinite wisdom
[00:40:09.100]says our soils are so rich that we don't need it.
[00:40:14.620][Marshall McDaniel] Oh boy.
[00:40:17.041]So yeah, I think biochar is a very good practice
[00:40:22.232]if you can afford it.
[00:40:23.873]Right now I think it's economically
[00:40:26.970]out of reach to a lot of farmers.
[00:40:29.280]And we actually, there's a soil chemist that I work with,
[00:40:32.661]that he's found some of the soil organic matter
[00:40:36.510]we have in our soils is biochar
[00:40:39.028]from past fires prior to cultivation.
[00:40:41.970]It's so persistent it sticks around in the soils.
[00:40:45.240]But biochar, those of you that aren't familiar with it,
[00:40:47.522]it's good at holding onto nutrients,
[00:40:50.130]has high cation and anion exchange,
[00:40:53.618]improves water holding capacity.
[00:40:56.280]There are many benefits to it.
[00:40:58.620]Problem is, we don't have a lot of trees in Iowa,
[00:41:01.320]and it's pretty tough to make
[00:41:03.543]that economically feasible right now.
[00:41:06.120]I hope that changes because there is a lot of promise
[00:41:08.669]with biochar, though. Thank you for that question.
[00:41:13.200]You have one up here.
[00:41:16.001][Audience Member 3] First off,
[00:41:17.682]Iowa State graduate agronomy 1981,
[00:41:18.990]just thought you'd like to talk to somebody friendly.
[00:41:21.067][Marshall McDaniel] Nice, nice.
[00:41:23.293][Audience Member 3] Something that has concerned me,
[00:41:26.375]and I'm actually a seed supplier and something
[00:41:29.820]that has concerned me in the past few years
[00:41:31.500]is I see a lot of farmers baling
[00:41:34.140]and selling their corn stalks.
[00:41:36.556]Have you done any research on the cost of that
[00:41:39.780]to the soil in terms of fertility and organic matter
[00:41:44.500]and how that evens out for what they're getting?
[00:41:47.490]I think a lot of them are thinking it's free money
[00:41:49.530]'cause they go out and sell them
[00:41:51.300]and I was just wondering what the cost would have
[00:41:54.180]to be in your soil and what the cost
[00:41:56.835]they're getting for the bales.
[00:42:00.788][Marshall McDaniel] That's a great question.
[00:42:01.621]Did everyone hear that? I'll repeat that one as well.
[00:42:04.980]So an Iowa State grad, thank you,
[00:42:08.791]asked about baling cornstalk or removing,
[00:42:13.871]and this is the same issue with removal of stover
[00:42:17.040]for biomass or any other purposes,
[00:42:21.360]and the idea is that you don't have that
[00:42:22.860]above ground residue reentering the soil.
[00:42:25.377]So we did one study where I believe it
[00:42:29.160]was 12 years we worked with the USDA ARS
[00:42:31.776]and (indistinct) and we didn't see any
[00:42:35.768]losses in soil organic carbon over that time period.
[00:42:40.170]But that changes very slowly.
[00:42:42.497]And I think most of carbon that
[00:42:45.227]cropping systems contribute is actually below ground.
[00:42:49.260]It's through roots and the stuff that leaks out
[00:42:51.660]of roots too over the growing season.
[00:42:53.790]Not to say residue's not important,
[00:42:55.500]there are other reasons that residue's important,
[00:42:57.930]but the major impact we saw in soils is potassium.
[00:43:02.280]But because there's so much potassium in the stalk,
[00:43:05.239]any grower that asks me about, you know, removing stover,
[00:43:08.790]I say watch your potassium levels,
[00:43:10.380]make sure you're testing your soils for potassium
[00:43:14.370]'cause we saw potassium depletion from that stover removal.
[00:43:18.600]Thanks for that question. That's a good one.
[00:43:21.398][Audience Member 4] Here's the next. Same place.
[00:43:23.677][Marshall McDaniel] Oh, right there.
[00:43:26.825][Audience Member 4] (indistinct), alright,
[00:43:30.170]so 16 years in these rotations that you have your data there
[00:43:34.200]and the four year rotation looks best with alfalfa
[00:43:37.020]and oats in it. So what do the farmers think?
[00:43:39.510]Are they adopting this, and if not, why not?
[00:43:43.619][Marshall McDaniel] What do the growers think?
[00:43:45.146][Audience Member 4] Yeah. What are they doing?
[00:43:46.804]What are Iowa farmers?
[00:43:47.893]Are they putting alfalfa in these rotations?
[00:43:50.311][Marshall McDaniel] They aren't as much as I'd like,
[00:43:52.380]let's put it that way.
[00:43:53.310]And some of those reasons are,
[00:43:55.680]it's outside my hands. Right?
[00:43:57.450]A lot of it is economic and market forces.
[00:44:03.120]Some of it is policy, you know, crop insurance too,
[00:44:07.354]it's not the same place for small grains, at least in Iowa.
[00:44:12.457]There are kind of many barriers.
[00:44:14.700]I think some of it's cultural too, right?
[00:44:17.970]You get used to corn, soybean,
[00:44:19.740]and that's kind of how it becomes, right?
[00:44:23.400]And so I, you know, I'm not a sociologist or psychologist,
[00:44:27.921]but I do like to think about that stuff because, yeah,
[00:44:31.134]I mean I want my work to be impactful
[00:44:33.630]and people to see the benefits and then go out and do it.
[00:44:35.790]But you're right it's not being adopted
[00:44:38.130]as quickly as I'd like.
[00:44:40.860]Okay, so in that oats and alfalfa one year,
[00:44:45.510]was any of that taken?
[00:44:47.550]Okay, so the oats and alfalfa was planted in the spring,
[00:44:50.351]and then was there a crop taken off?
[00:44:52.380]Is there an oats crop off?
[00:44:54.915][Marshall McDaniel] There is,
[00:44:56.676]the oats are harvested in July
[00:44:58.740]and then the alfalfa goes and we just
[00:45:01.650]cut the hay a few times usually.
[00:45:04.042][Audience Member 4] So there is an
[00:45:04.920]income from the oats in that year?
[00:45:07.406][Marshall McDaniel] There is and that's in
[00:45:09.758]that profits number that I gave you.
[00:45:12.330][Audience Member 4] Okay and so then the alfalfa
[00:45:13.932]the following year is a cash crop or you know, you haven't?
[00:45:18.668][Marshall McDaniel] Yeah,
[00:45:19.626]we used the hay values at that time.
[00:45:21.938][Audience Member 4] Okay. That's all I had.
[00:45:23.819][Marshall McDaniel] Thank you. That was a good question.
[00:45:26.700]I should have clarified that in the profits numbers.
[00:45:31.067][Audience Member 5] My question is about something
[00:45:32.370]you just mentioned briefly at the end.
[00:45:34.320]Between the four year and the two year treatment,
[00:45:36.600]they received different tillage
[00:45:38.730]with the moldboard plow in the four year.
[00:45:40.980]Can you just clarify and maybe speculate
[00:45:43.078]those increased metrics that our
[00:45:45.180]first question talked about,
[00:45:46.800]if that could have something to do with it?
[00:45:49.605][Marshall McDaniel] The increase,
[00:45:51.120]can you clarify that last part? Like the increase?
[00:45:53.958][Audience Member 5] So the few metrics
[00:45:56.688]that were increased in the two year?
[00:45:58.094]Just speculate what you think.
[00:46:00.096][Marshall McDaniel] Oh, I see, okay, yeah.
[00:46:01.821]So the question was about tillage,
[00:46:05.185]the fact that we had been doing tillage up until year 20
[00:46:09.029]and then maybe why the two year
[00:46:12.311]was greater with the Haney test.
[00:46:15.300]And I think there was one other thing.
[00:46:16.980]So that could be it, right?
[00:46:18.390]And often I have discussed this with folks.
[00:46:23.250]So the moldboard plow we sampled in the corn year,
[00:46:26.488]which is right after the plow happens.
[00:46:29.220]But we sampled three different time points
[00:46:34.457]from those data up there, and microbial biomass is greater.
[00:46:38.520]This is the thing that really puzzles us, right?
[00:46:40.440]So usually microbial biomass and the CO2 burst,
[00:46:44.040]which is a measure of activity from the Haney test,
[00:46:46.787]usually those things go hand in hand
[00:46:48.630]and we'd expect the same direction, but they're not.
[00:46:52.080]We have some other theories of why that might be.
[00:46:54.030]Like maybe the microbes are actually more efficient
[00:46:57.420]so they're not giving out as much CO2
[00:46:58.974]even though there's more micro bodies there.
[00:47:01.680]That's actually a good thing for building soil carbon.
[00:47:03.870]There's some papers that show that.
[00:47:06.743]But yeah, that's our best guess right now.
[00:47:09.750]Great question though and it'll be neat
[00:47:11.430]to go back and resample after now
[00:47:13.320]that we've got everything in no-till,
[00:47:15.150]maybe five years from now or something.
[00:47:17.640]I need to find a good student, if you know any.
[00:47:21.180]I'll be around most of the day, yeah,
[00:47:22.950]if anybody has any further questions
[00:47:24.480]or my contact info's up there.
[00:47:26.680][Audience Member 6] On the alfalfa used
[00:47:28.080]in your four year study,
[00:47:30.644]the following year, it goes back to corn I'm assuming?
[00:47:33.966][Marshall McDaniel] Yes.
[00:47:35.648][Audience Member 6] Have you done
[00:47:37.089]any research or anything 'cause alfalfa's a multi-year deal
[00:47:39.092]that you can go up to five years on alfalfa?
[00:47:41.430]Have you done anything beyond the four
[00:47:44.610]year study with alfalfa?
[00:47:47.218][Marshall McDaniel] No, I have not.
[00:47:48.540]So the question was and I know a lot of growers do
[00:47:51.824]three to five years because of, you know,
[00:47:56.940]the short term research and small plots,
[00:48:00.231]we decided just about a year and a half of alfalfa,
[00:48:04.170]but many growers might do three even up to five years.
[00:48:07.522]I think the benefits would even be greater.
[00:48:11.940]One thing about alfalfa that most of you
[00:48:14.488]probably already know is it's one
[00:48:16.289]of the best nitrogen fixing crops and is deep rooted.
[00:48:18.420]I think that's one of the major contributors
[00:48:20.610]to the benefits we're seeing up here.
[00:48:23.215]And the more years of that the better
[00:48:26.280]if you can make that work on your farm.
[00:48:29.381]But no, there are some, I think,
[00:48:31.983]maybe there are some other experiments
[00:48:35.610]that have looked at a little bit longer years
[00:48:37.470]of rotation maybe in Wisconsin.
[00:48:40.260]I think they've got a two year, a three year.
[00:48:45.990]Well, thank you.
[00:48:47.516]Thanks Marshall for this very informative talk.
[00:48:48.780]Let's give them a round of applause.
[00:48:51.080][Marshall McDaniel] Thank you.

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2023 Eastern Nebraska Soil Health Conference - Marshall McDaniel

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