Cover Crop Mixes: Getting the Cover Crop You Want
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Our presenter today is a
native of Milwaukee in Wisconsin, and has earned his
bachelor’s of science degree from the University of Wisconsin
at Stevens Point. He’s recently completed a
University of North Dakota postgraduate study program in geographic information science. Over the course of Jon’s career,
he’s worked as a dairy herdsman in southeastern
Wisconsin, and an integrated pest management field scout
for the University of Wisconsin Cooperative Extension
and mapping soil scientist in East Central
Illinois. In North Dakota, Jon has worked
as a mapping soil scientist in the East Central
part of that state, as a soil conservationist in Sheridan and
Burleigh counties, and as a district conservationist
in Griggs, Steele and Dunn counties. He’s been in the area of
agronomy for western North Dakota, and currently is the
area resource soil scientist in that area. He’s been actively involved as
an advisor, and webmaster for the Manitoba – North Dakota
Zero Tillage Farmers Association, the North Dakota
chapter of the Soil and Water Conservation Society, and
recently completed a project called the Southwest North
Dakota Soil Health Demonstration. He’s been actively learning and
teaching about soil health since 1992. And, of course, he grows his
garden without any tillage. And so I’d like to turn this
presentation over to you, Jon, and let’s all enjoy this
afternoon’s presentation. Jon. It’s my pleasure to be here
today to cover what I know about cover crops. Cover crops have been around
for a long time, but more recently, we’ve been using them
for some new purposes and for some new approaches to
improving soil health. So that’s what I’d like to share
with you today in my presentation. First, I’d like to cover a
little background information on soil health. Then get into the thought
process of developing your own cover-crop mixes. And then a little bit
of a case study information at the end. So with that, we’ll
get rolling here. I realized when I started
putting this information together that there was no way I
was going to be able to tell everybody exactly what they
should do for every situation in every part of the country. What I wanted to share with
you today was what I have learned, mostly from producers,
on cover crops and how cover crops are
used these days. This practice has been around
for quite awhile, but more recently, we’ve been looking at
how we use cover crops for improving soil health and
a lot of other purposes. So that’s pretty much what I
would like to discuss today. I’d like to start out with some
background information on soil health, then get into some
discussion on developing cover crops, and then a few
cover crop case studies. And when I started putting this
information together, I realized that I can’t give
everyone an answer of what cover crop they should grow for
what purpose in their part of the world. So I’m really not going to give
you a lot of answers, but help you realize what questions
you’re going to need to ask yourself as you go
through your thought process of deciding if and when, and how
and what you’re going to use for a cover crop. This image here is just an
example of a cover crop that was broadcast in the
standing corn. But the first thing I think
everyone needs to ask themselves is what
is your goal? Don’t make the use of a
cover crop your goal. Have a goal in mind of improving
soil health and having some other purposes with
the use of a cover crop. Don’t grow a cover crop just
because that’s the in thing to do right now. Really think this through and
decide what is your goal? What do you want that cover
crop to accomplish? And what we’re realizing, is
that cover crops, particularly these mixtures of species, can
be an excellent tool to help restore and improve soil health
and soil functions. And we’ll get into that
here a little bit. So restoring and building soil
health is a very worthy goal that you can use a cover crop
as a tool to help you get down that road. As I was digging in some
other information– I’m kind of a student of Thomas
Jefferson, and came across some information in his
garden book that he kept, and the fact that he used turnip,
buckwheat and vetch as cover crops at Monticello
back in 1794. And how he realized that it was
important for him to have some crops, some cover crops,
that would build the soil to alternate with his cash crops. So a little bit about
soil health. Soil health is the continued
capacity of the soil to function. And I have the words, function
and living highlighted there, because that’s really what we’re
talking about when we refer to soil health, is how
well is your soil functioning? And we have to understand that
it’s a living system. It’s a biological system. And once we change our thinking
to realize that the soil is a biological system,
it’s a living system, then our approach to soil management
changes. And we begin to realize that
what we’re doing here is creating habitat for these
things that live in the soil and drive all of the processes
that we expect the soil to perform as an agricultural
system. So when we look at cover crops
from a soil health perspective, they’re really
functioning as a primer of soil biology. They’re providing this food
source and this diversity that the soil food web really
thrives on. So we’re finding that if we put
these multi-species cover crops out in our systems, that
they’re really priming the soil and bringing it to a higher
level of function. So we need to think about
feeding the underground herd as it’s been referred to. And if we could round up all of
these microorganisms in the soil and run them across a
scale, like we could cattle, we would have at least
two cow’s worth. It’s probably closer to five
cow’s worth, but at least two cow’s worth of soil organisms
per acre. So if you can imagine two cows
standing out on every acre of your land needing to be fed,
that’s really what we need to understand as we manage our
cropping systems and grow these cover crops. So the soil food web in this
diagram I borrowed from the soil health primer, or soil
biology primer, and I like this diagram, because it really
emphasizes what we need to understand, and what we
need to think about, when we’re managing these systems. So this system of the soil,
as a biological system, is supposed to be powered
by the sun. And that sun through
photosynthesis of green growing plants, provides the
sugars that exuded out of these plant roots, the residues
from these plants, that feed all of the smallest
members of the soil food web, bacteria and fungi
in particular. Then as these organisms are
consumed by larger organisms as we move through the food
web, that’s where more nutrients are made available
to the plants. Whenever someone gets eaten in
the soil food web, that excess nitrogen as those carbon
nitrogen ratios change, that excess nitrogen is fed
back to the plants. So the plants are able to feed
the soil using the sun as a source of energy, and then the
organisms in the soil are able then to feed the plants. And we have these cycles that
are powered by the sun. This is how the soil is
designed to function. So if we do our best in our
management systems to mimic nature and manage the soil the
way it was designed to function we’re finding that
our systems are much more productive, and efficient,
and profitable. So this is our toolbox. Green growing plants are the
tools in our toolbox. We need to think about when we
want to manage the soil. We need to think about managing that soil with plants. So we should be reaching for
seeds rather than steel. To do tillage, we should be
reaching for seeds to grow the plant or plants in that soil
that will address whatever it is we need to manage
that soil. So when we get right down to
it, all of the things that happen in the soil that we rely
on from an agricultural perspective, we expect the soil
to infiltrate, and store water, and supply nutrients
to the plants. And really, what it’s all
about, is this habitat. And in the world of soil
organisms, soil aggregates are their habitat. And you can see in this little
image down in the lower right, an aggregate forming, the sand
grains, the silt, the clay, other things being glued
together by the glue that’s produced by bacteria, fungi,
plant roots, earthworms, et cetera, that glue these
aggregates together. And it’s important to understand
that we can’t create aggregates
with tillage. We can only break these
aggregates down with tillage. It’s these glue makers, these
organisms that live in the soil and plants, that can build
the soil aggregates, and create this habitat and this
structure in the soil, that allow it to perform the
functions we expect it to perform, and to provide the
habitat for the organisms so they can do the nutrient
cycling. An easy way that we use to
assess soil health, is just to look at aggregate stability. Look at how good are these
glues holding the soil aggregates together. So if you take a piece of soil
off of the surface of your land, or the top few inches of
your land, those natural aggregates, those clumps and
clods that it breaks into, let them dry out, so they’re air
dry, and then drop them into some water, you’ll get a very
good measure or indication of how well is my soil
functioning? How good is the glue holding the
aggregates together, and how well is this habitat
stabilized in the soil. When that water rushes into the
aggregate and pushes the air out, if the glues are of
high quality, that aggregate will hold together as in
the image on the left. If that air rushes out as the
water rushes in, and the aggregate explodes and
disintegrates in the water, then that’s an indication
that your soil habitat is not very stable. The quality of your organic
glues is not very good holding that soil together. When it rains, the soil gets
wet at the surface, those aggregates disintegrate
when they get wet. At the surface, they plug the
system, and the water has a very difficult time infiltrating
the soil, and you see a lot of water run
off the field. So we really don’t have a water
runoff problem, we have a soil, water infiltration
problem. And that can only be solved by
feeding soil biology so they can make these glues that will
stabilize our soil aggregates. Where a lot of this takes place
is in this area right around the roots of living
plants, which is called the rhizosphere. And this area of concentrated
activity is where all these glues are made, where all the
nutrients are cycled, et cetera, which is very convenient
to the plant because the nutrients are then
made available right next to the root where the plants
can absorb them. So in this image here, I just
took a barley plant, an actively growing barley plant
that I dug up, took the soil off, but a lot of soil was still
clinging to the roots of this plant, because there are
sugars being exuded by these plants, all these organisms are
living right in this area where all this easy food is
being made available. And so we have a lot of sugar,
a lot of glues, a lot of activity right there causing
the soil to cling to these roots when we dig
these plants up. But it’s a nice visual of how
all of this is happening in this rhizosphere right next
to the plant root. So for the keys to the kingdom,
so to speak, for managing for soil biology and
soil health, there’s really four key things that I look at
and explain to folks when they’re thinking about how can
I manage my soil to improve soil health. And those four things are to
minimize soil disturbance as much as possible. There are some situations where
there’s going to be a certain amount of soil
disturbance, but look for the ways that you can minimize the
disturbance of the soil. A lot of producers in my part of
the world here have gone to no-till, so that they have the
absolute minimum amount of disturbance to the
soil every year. Maximize diversity of plants in
your rotation, and this is huge, and this is where cover
crops are coming in and having a very significant impact. As we need to get as many
different types and species of plants growing in that soil as
possible, because we have a huge diversity of organisms
that live in the soil that need to be fed. And keeping living roots in the
soil as much as possible, provide those organisms with
their easiest food source. Those sugars that are exuded
from those plant roots is the easiest food source for them
to assimilate and grow. So cover crops come into play
there where we have living roots out in that soil for an
extended period of time beyond, or in addition to, what
we normally have with our cash crops. The fourth thing is to keep this
all covered with plants and plant residues all of the
time, so that we buffer the soil habitat so it’s not
exposed to extremes in temperature and moisture. And we provide the food source
for part of the soil food web that lives at the soil surface
that lives in that residue that starts to shred that
residue apart and get it fed into the soil system. So if we were going to boil
this down to one point, it would be to create the most
favorable habitat possible for the soil food web. I got a kick out of this little
diagram that I came across of the two rabbits and
their carrots, because when we’re talking about
cover crops, it’s the part below ground– for me, it’s the part below
ground that is the most significant, because that’s
what’s feeding the soil food web. Yes, we need to have the
top part of the plant to cover the soil. That’s important, but we tend
to look at the part of the plant and the production at
the surface, rather than looking at the impact that the
plant is having in the soil. OK, so that’s kind of the quick,
the short course on soil health. Before we actually get into
the cover crops part, were there any questions? We’re not seeing any questions
right now. For the group, please type the
questions into that notes transcript box. Thanks. OK, now to get into a little
bit more of the cover crops thought process, the first
question in my mind would be, why even bother growing
a cover crop. What am I going to grow
this cover crop for? And the first one in my mind, is
to feed the soil food web, so that I can build the
capacity of my soil to function, to perform the
functions I expect it to perform when I want to
grow my cash crops. Another purpose might be to
provide some supplemental forage for livestock, provide
soil cover at a point in the rotation or a time in our
cropping system, when we might not have a lot of soil cover. Provide wildlife food or cover,
capture and cycle crop nutrients, and this one can be
very important in places where you may have an excess of
rainfall at certain times of the year. And the best way to keep those
nutrients from escaping through runoff water or
groundwater, is to get them tied up into some plant tissue,
so that they’re held there until that plant tissue
decomposes and then becomes available to the next crop. We can use the cover crop to
fix some nitrogen, some atmospheric nitrogen by
including some legumes in our cover crop. In this part of the world, it’s
important for us to catch some snow in the winter time. That’s a significant part of
our annual precipitation. So if we can catch that snow
that adds to our water supply and dry land agriculture,
depending on what species you have in your cover crop, and
what degree they mature, we may be able to support
some pollinators with our cover crops. And we can create pores through
the soil, through compacted layers in the soil, we
can create pores with these cover crop root systems. So this is just a short list out
of all the things that I’m sure folks could think of, that
they might want to have as a reason to grow
a cover crop. So how do cover crops
improve soil health? And cover crops, we think back
to that diagram, we have the green plant photosynthesis
feeding the soil food web. So the longer we can have
something green and growing out there, the more we’re
supplying that easy food to the soil food web. And if we have a diversity of
plants in our cover crop mix, we feed that whole diverse food
web of organisms in the soil that much better. From my observation, if we have
living roots of a cover crop in the soil for at least
a six-week period, we’re seeing significant nutrient
cycling to the extent that, the nutrient cycling, the
nutrients that are supplied to the next crop, are usually equal
to the money that we’ve spent on the cover crop. So don’t necessarily look at a
cover crop from the biomass that it produces above, but
think about how many weeks has that plant been green and
growing, and feeding the soil, and not measure so
much how much production is above ground. We also want to produce that
residue, that biomass, that will cover the soil, because
that’s an important part of buffering that soil and feeding
the soil food web. So cover crops can really play
a big role in feeding the soil, improving soil health,
if we have the diversity of species in there, and we can get
at least six weeks or so of growth out of them. So some of the questions we need
to ask ourselves as we plan for our purpose, is when
and how are you going to plant this cover crop? Is it going to be planted with
a drill, or a planter, or broadcast, or flown on
with an aircraft? What species are you
going to include? How many different species
and which ones? How are we going to terminate
this cover crop. Here, winter terminates our
cover crops pretty handily for us, but you may look at other
methods and timing of when you would want to terminate a cover
crop by rolling it, or grazing it, or spraying it. And then, how much coverage is
this cover crop going to leave on the soil, and when is that
residue going to be present? Is it going to cover the soil
during the time that we need it to cover the soil? Planting, the timing, if we’re
going to look at planting our cover crop before we harvest,
or after we harvest our cash crop, and what time of
year would that be? What is our moisture
conditions? Are we going to be able to drill
that, or use a planter, or broadcast that seed. Think about the planting depth
and the seed size. Most seeds don’t really need to
be planted any more than, any deeper than twice
their diameter. But when you’re planting these
cover crop mixtures, we have large seeds like peas or beans,
and small seeds like canola and radish turnip. We found that if we plant things
about an inch deep, it’s kind of a “Goldilocks” zone
where everything can grow from there. We can mix a lot of these
seeds prior to planting. They can be purchased all mixed
together and dumped in the drill or planter
mixed together. Or we can put them into a
drill and mix them once they’re in the seed box if
we’re only doing a small amount at a time. If legumes are going to be
included in your cover crop mix, you need to be aware of
which inoculant you need for each particular legume, whether
it’s Rhizobium or Bradyrhizobium, or whatever the
case might be, so that you make sure that you get the right
bacteria growing with that legume and get those
benefits of fixing nitrogen from the atmosphere. You may want to do a pre-plant
herbicide burndown before you plant your cover crop, depending
on what your time of year is, or your
weed pressure. That’s not always necessary, but
in some cases, producers are going to want to do that to
make sure their cover crop is the crop that gets the
advantage, rather than some weeds that might be coming. And then to decide whether or
not you’re going to include any fertilizer when you
plant that cover crop. In most cases, fertilizer isn’t
necessary, but there may be reasons that you would want
to put some fertilizer out there for the cover crop to
take up and hold for you. Or if you’re at a very degraded
situation, you might need something like
that to help your cover crop get started. When we’re looking at species
composition, what we found so far, and what we’ve realized
from looking at some of the literature, is the more species
the better is the short answer. But we found that if we have
at least five species in a mix, we seem to have less weed
pressure, fewer weeds showing up in our cover crops, and
those cover crops seem to produce more, grow better
overall, the greater diversity of species that we
have in there. We also like to see at least
three functional groups. So we think about warm season
grasses, cool season grasses, cool season broadleafs, warm
season broadleafs, and legumes as basic functional groups. And we’ll get into that here
a little bit more. The season of growth, if you’re
planting a cover crop, and it’s going to do the
majority of its growing during the hottest part of the year,
then you may want to lean more towards warm season species. Or make sure you have warm
season species in your mix, so that they will grow during that
warm period of the year. What you’re moisture conditions
are going to be, grow some things that can
tolerate maybe a little bit drier conditions if it’s in
the summertime or wetter conditions if it’s
in the spring. Temperature, there are some
species that cannot tolerate much frost, that will die when
you get a light frost. And there’s other things like
turnips that it needs to get pretty cold, down to 10 or
12 degrees before it will actually kill them. So we can manage how our cover
crop is going to perform by thinking about what are all
these conditions going to be like during the time
this cover crop is going to be growing. And we can decide if we’re going
to use some annuals, or biennials, or perennials in our
mix depending on what our goal might be, and how long
we want all these things to grow out there. Cost and availability
is also an issue. The availability of a lot
of these things is becoming a lot easier. They’re a lot easier to find
than they used to be. But we do like to keep the
cost down, so that we can achieve our goal without
spending any more money than we really have to. We need to pay a little bit
of attention to the carbon-nitrogen ratios
of the mixtures that we’ll have out there. And at what stages they will be
terminated, so that we can figure out how much and how fast
these things are going to decompose, or how fast they
might decompose the existing residue that’s already
out there. And the last thing that we’ve
kind of found out the hard way, was herbicide carryover,
paying attention to what herbicides have been
used on that field. And if there’s going to be a
carryover that might take out broadleaf species that
we might have in our cover crop mix. So pay attention to that, so
that whatever we plant out there will grow. Just a couple of little graphs
here that, from some work by Dr. Tillman, on species
diversity. And what they found if you look
at the graph in the upper left there, we look at species
diversity when you have at least five to 10 species in a
plant community or in a cover crop mixture, that’s kind of
the peak of the curve of biomass production. So we kind of found that out
with our own observations, and then we found this research that
supports it, but that’s where these numbers come from. We’re trying to hit that sweet
spot in the curve there to get the most production out of these
things, and that’s why we suggest using at least
five or more species. And if you look at the graph in
the lower left, there you can see that the curve starts
to flatten out when we have three functional groups– the cool and warm season
plants, the grass, the broadleaf type plants, legumes,
are some of the basic functional groups. And we’ll get into that in a
little bit more detail at the end here when we get into the
cover crop calculator. So when it comes time to
terminate these cover crops, like I said, here, North Dakota,
we can usually rely on winter to do that job for
us except for a few winter hardy species. It may be dry enough that it
will terminate the cover crop. I know in some of the irrigated
country and in Idaho, they can just quit
watering it, and it’ll dry up enough that the cover
crop will be terminated by drying up. We can graze these cover
crops to terminate it. The caution there is to not
allow the livestock to consume all of the cover crop, so that
we don’t have a cover on the soil, we’re not feeding
the soil food web. So we need to be aware that,
and ideally, only let those grazing animals take less than
half of what’s produced, and leave the other half or 60% or
so on the soil to feed and cover the herd that lives
below the soil. There’s some nice rollers that
have been developed recently with the Chevron pattern. I’ve seen folks use old culti
packers and things like that as rollers to roll some of these
cover crops down just as they are flowering or just
before they flower. And a lot of times that will
kill most of them just rolling them and breaking the stems. We can also use herbicides to
terminate these cover crops when necessary, whether we’re
concerned about moisture use or just timing of our next crop
or crop insurance issues. We can go out and terminate
those cover crops that way. Or just let them grow to
maturity if they’re mostly annuals, and they’ll senesce
and die on their own. So the other portion that we
need to look at is, how much cover are we going to have on
the soil when this cover crop is growing? How much growth are we going to
get before it gets too dry or too cold, et cetera? How much cover are we going to
have after that cover crop is terminated? And how much of that residue is
going to survive over the winter or over some
fallow period? And how is that going to
feed the soil food web? And like I mentioned, we need to
be careful of having enough residue after grazing that
we don’t leave bare soil. Just a little bit more about
carbon-nitrogen ratios. The higher the carbon-nitrogen
ratio, the slower the rate of decomposition. The lower the carbon-nitrogen
ratio, the faster the rate of decomposition. And you can see that the
carbon-nitrogen ratio for a particular species like
rye, will depend on how mature it is. So rye straw, mature rye, has a
much higher carbon-nitrogen ratio than rye when it’s still
in the vegetative state. So you need to think about how
mature are these species of plants going to get when
they’re going to be terminated, and that
will determine your carbon-nitrogen ratio. If that carbon-nitrogen ratio is
at or below 30 or so, odds are most of it is going to
decompose fairly rapidly, and you may not have a lot
of soil cover. So the high carbon cover crops
can cover the soil, increase organic matter, capture and
recycle nutrients, and moderate soil temperatures. Our lower carbon cover crops,
such as legumes, or some of the brassicas or the grasses
in their early stages of development, can fix the
nitrogen, are very efficient at using nutrients and will help
us break down high carbon old crop residues if that’s
part of our goal. We can throw these into a
combination and get lots of different benefits building
that soil structure, increasing aggregate
stability, but most importantly, increasing
biodiversity out there, which reduces our weed, insect, and
disease pressures and really helps feed that soil food web. So we need to plan for that
diversity and look at including species in our cover
crop that are already in our crop rotation. So if we already have a crop
rotation with a lot of cool season grasses in it, it’s
probably a good idea to include warm season grasses,
cool season broadleaf and warm season broadleafs in our cover
crop, so we have a greater diversity of species that aren’t
already represented in our crop rotation. So the more species, the better
as far as the soil food web, as far as diversity
and production. If you look at the image in the
center at the bottom, it shows a cover crop in Montana
after a frost where you can see some of the species have
died from the frost, while some of the species
continue to grow. OK, what about water? This is a question that I get
from time to time that our cover crop is going to use up
our water, particularly in dry land systems, and we’re not
going to have enough water to grow our cash crop. Here in North Dakota, Western
North Dakota, some studies that have been done have shown
that we have about a 80% chance of success as far
as water is concerned. If we grow a cover crop that’s
going to use water late into the season, and expect to have
enough moisture the following growing season, you’re going to
have to evaluate that for yourself in each part
of the world. But generally speaking, these
cover crops aren’t using any more water than we were letting
evaporate from bare or unprotected soil in the past, so
it’s about a horse apiece. And when we look at how these
plants behave when we have them in mixtures, some
interesting research on a topic called the stress gradient
hypothesis, which I refer to on the other two
graphs showing the five different species in the three
functional groups. As you grow plants in
collections of different species, they collaborate
more than they compete. The images on the bottom there
show a turnip cover crop and a reddish cover crop that we’re
growing in some cover crop demonstrations here a few years
back in Bismarck when we had a very dry summer. And where we have the single
species of turnip by themselves, or radish
by themselves, they pretty much died. They ran out of moisture
and died. But where we threw all the
species together in a mix, even though we only have less
than two inches of growing season precipitation, they
flourished and grew. So when we looked at, clipped
and weighed what was produced there, we could see by the
pounds per acre, that where we had these species all mixed
together, we had a great deal more production. And those plants were alive,
and green, and growing, and feeding the soil food web a
lot longer period of time during the year than when we
had each individual species alone in a monoculture. So when you’re developing your
cover crop mixes, ask yourself what’s the purpose
or purposes. There may be more than one
purpose that you want your cover crop to serve. Include crop types and species
that are not already in your crop rotation, have a minimum of
five species of plants, and at least three functional
groups. And in our part of the world,
we found that if we have at least 20 pounds per acre of
seed, we usually get a pretty good stand without
a lot of weeds. More than 20 pounds per acre is
fine, but once we got up to 40 or 50 pounds per acre, we
realized that they’re probably spending money on seed and not
seeing as much return. And so, it’s just more of an
economic reason for not going beyond 40 pounds. But at least 20 pounds and five
species seems to work pretty well, at least here and
most of what I’ve dealt with in the Great Plains here. Look at your time and method of
planting, and your time and method of termination. If you can answer these basic
questions, you’ll be well on your way to a good cover
crop experiment. Now this table is in the
handouts, and I don’t expect you to be able to read this,
but I just took a little snapshot of a table that we use
here in North Dakota to help us look at these different
cover crop species and their characteristics as
far as their rooting depth where they could provide
supplemental grazing, things like that, while we’re
developing these mixtures. Another tool that I want to show
you here at the end is available at greencoverseed.com. You can see the web address at
the bottom of the slide here. And not promoting Green Cover
Seed as a supplier, but they have a really nice little
calculator that you can play with to look at how you
want to develop your cover crop mixtures. And I want to jump to that here
at the end, so you can take a look at it in
a live version. So just a few, I don’t know if
you want to take any questions right now, I have just
a couple things on some case studies. We have a question
on planting. There’s a technique slurry
seeding with manure. Have you had any observations on
that practice or experience with that, Jon? I don’t have any experience
with it. I haven’t seen it done, but I
have read where folks have been including cover crop seed
when they’re applying their manure slurry. And from what I’ve seen, it’s
been successful most the time. They haven’t had any real big
failures with it, so I think it would be a very viable
approach to get that done all in one shot. OK, now in terms of species
diversity, there could be some wide variation among cultivars
of certain species. Could we count different
cultivars as different species, or would we not lump
those, not be able to split those out and really need to
have distinct scientific species in that mix? I tend to look at things as
diversity as separate species, but if you did have different
cultivars within a species, I don’t see any problem with that,
as long as we had enough overall diversity in the mix. You might want different
cultivars of millet for their different graze-ability
or their different carbon-nitrogen ratios. But I tend to look at species
as species, and not necessarily cultivars for
purposes of diversity. OK, now on the topic of grazing,
is grazing a cover crop compatible with a 340
cover crop standard? That I would have to check, but
as long as we’re leaving enough residue out there to meet
the goals of what that cover crop was designed
for, I don’t see why it would be an issue. Good, now, quite a few
no-tillers noticed an increase in slug damage. And there’s concern that adding
these cover crops with all this residue and organic
activity, that it could make the slug problem worse. Do you have thoughts on this? We don’t have so much of an
issue here with slugs, but we sometimes have situations
where we grow crops that produce a lot of residue
like winter wheat that’s very high carbon. And we want to get that stuff to
break down and cycle before we would go to another crop,
where that excessive amount of residue might be an issue. And so we’ve planted some cover
crop mixes that are very low carbon-nitrogen ratio that
have a lot of the legumes, turnips, radishes, things
like that, to get that residue to decompose. So while that cover crop is
green and growing, that might be attractive to slugs, but
after that, it may get some of that residue to decompose where
you wouldn’t have quite the volume of residue
on the surface. Now, a lot of our audience are
in dairy producing areas, and a very popular dairy crop is
a pure stand of alfalfa. And so we have during a four
or five year cycle in a rotation, a single species in
those fields that’s really pretty weak on diversity for
long portions of the rotation. Have you seen people trying to
address the diversity, lack of diversity, in some of these
rotations, and anything that you might offer as
a suggestion for these kind of systems? Well, this case study that I
have up on this slide right now from Montana, this
individual had a pasture that was, basically, dominated by
crested wheat grass, a single species of cool-season
perennial grass. And it was declining quite a
bit, so he decided to plant this multi-species cover crop
that included a few additional species of perennial
grasses in there. To not only produce some
short-term forage to save him some money during this drought
when he would have had to buy hay, but also to add the
diversity to the soil to stimulate that soil and prime
that soil so that the grass species that he had out
there would respond. Instead of reseeding the field
or applying fertilizer, or things like that, he decided to
use this biological priming of this cover crop to get this
soil to move to a higher level of biological function to
increase his grass production. And we’ve done similar things
with pure stands of alfalfa where we’ll drill cover crop
mixtures into these declining stands of alfalfa to add this
diversity to the soil and get it rejuvenated, so to speak,
to increase the subsequent production on the alfalfa. When working with an organic
grower that can’t rely on herbicides for weed control,
would you recommend higher seeding rates to increase the
smothering performance of the cover crop? Certainly, and I mentioned
the 20 pounds per acre as a minimum. If you’re concerned about weed
pressure, to maybe include some species in your cover crop,
such as buckwheat, that tend to be very competitive and
up your seeding rates, so that your cover crop is what
dominates it and gets ahead of the weeds. We look at a cover crop seeding
that has at least 20 pounds and five different
species, when we walk out in those mixes, we see
very few weeds. But if we have a lower seeding
rate or fewer species, we’ll see more weeds out in
those plantings. When we’re trying to jump start
the soil biology with cover crops, and we’re
transitioning into this system, would we opt for lower
carbon to nitrogen ratios at below 24 to one? Would that help us in the short
turn to meet our longer term soil health objectives? As long as you’re careful
to not have such a low carbon-nitrogen ratio that you
end up with bare soil would be my caution. So yeah, legumes can be
an excellent thing. Including species in your cover
crop that are not in your crop rotation is, also,
one that has really made a difference in jump starting
the soil biology. You showed a producer mixing
multiple species in the drill hopper. So by mixing something– different seed size, Australian
pea, large seed versus with radish and it’s
a small seed, is there any trick, or is there difficulty
in keeping the species mixed up in the grain bins, it’s
planting a number of acres that we’re trying to cover
with a full hopper? We thought that would be an
issue when we did some of these, but we realized
that it really isn’t. Those seeds don’t sort
themselves out as much as you would think they would. If you were planting a mixture
that had very small seeded things like alfalfa or some of
the clovers, along with some very large seeded things, and
not a lot of other species in the mix, there it might be
advantageous to put those small seed in a separate
legume box. In a separate box metered
separately, so that you get a better distribution
of your seed. But with these diverse mixes,
we have such a range of seed sizes that they really don’t
sort out as much as you might think they would. You don’t see, Jon, you talk
about a general recommendation of 20 pounds per acre with the
different sizes of seed. How many seeds are we
really looking to drop on a square foot? How do we put that in context
of density, and numbers of plants being seeded? I guess I don’t usually
look at those plants per square foot. We calibrate the drill for that
many pounds per acre and go from there. I don’t usually look at it as
seeds per square foot, but a guy could sure figure
that out. And again, exposed with that
diversity of functional groups, we’re going to have some
large, some small, and well graded as far as
feed [INAUDIBLE]. Yeah. And one viewer mentions the
Midwest Cover Crop Council website that serves like six or
seven states in the Midwest as a great resource for looking
at current research being done in cover-cropping,
including the flurry seeding method. Yes. Yes, that’s an excellent
resource. OK, very good. Thank you, thank you very much,
and I’ll turn it back to you now, John, to go on with
your next portion of your presentation. OK. So I guess I already told the
story on this little cover crop that was used in Montana
on some perennial grass pasture and hay land to
rejuvenate the stand, so that’s something that we’ve done
in a situation other than just normal cropland. In New Mexico, just a quick
example of how they would manage pecan orchards. And now, they’re looking at– they’re still using drip
irrigation, but they’re putting some perennial cover
crops in between these rows of pecans, and feeding the soil,
and actually, keeping that soil a little bit cooler
and a little bit more biologically active. And it’s reducing, particularly,
their pest pressure, because there’s a lot
of parasitizing insects that live in these cover crops
that will help control the insects up in the trees. So instead of having a
biological desert out there, they have some diversity and
some life that actually helps them in their integrated
pest management. Just two examples from Idaho,
whether they’re using it to provide some cover after potato
harvest, or provide something for grazing, or just
to add some diversity to some of these crop rotations. And some of these are dry land,
and some of them are irrigated, but they’re doing a
lot of interesting things just getting some cover out there,
feeding the soil during an extended period of time when
that soil would’ve otherwise laid fallow. And the last little case study
from North Dakota here that I wanted to show on Richter Farms
where they had the goals of having soil cover, diversity,
increasing soil organic matter on very sandy
soils, increasing water infiltration, and nutrient
cycling, and integrating livestock into this
whole picture. So here’s the mix of species
and amounts that they had. And you can see, they were
upwards of 30 pounds per acre with different crop
types, different species in their mix. And here’s what it looked like
back in August of 2007. And when we have when the
Burleigh County Soil Conservation District has tours
out there, they usually get hundreds of producers. And we’ve joked about if we
ever wanted to terminate a cover crop by rolling
it, instead we just have a tour out there. And if we have hundreds of
producers, we could walk them across the field, and they could
roll that cover crop for us at the same time. OK, so they’re weighing these
calves that they’re going to graze this cover crop
with cow-calf pairs. So they’re weighing the calves,
and they turn these cow-calf pairs out there for
a period of 10 days in this cover crop. And they work their way through
eating what they like first, obviously, or what
they’re familiar with, and then working through the other
species that are out there. But we’re feeding the cows,
and we are feeding the underground herd. So then we weighed the calves at
the end and found that they gained about three pounds
a day which is a pretty respectable gain. Doing the numbers on that, the
numbers of calves and what they gained, we grossed over
$100 an acre by grazing this cover crop. And then we look at the cost of
the seed, the seeding, and the herbicide that was used
ahead of seeding at $45. And we do the rest of the math,
they found that they made $66 an acre from grazing
those cover crops. Now the advantages that they
had on giving more recovery time on native range land is
not factored into this– how much it improved soil
health, and how much it improved the body condition
of the cows– this is just looking at the
weight of the calves. So there are a lot of other
benefits, but they found they came up about $66 an acre ahead
by growing this cover crop and grazing it. In another situation– Jon, this is Mark. I do want to point out that
we’re at 3:06 Eastern, so we’re well into finishing
the first hour. And so we want to maybe moderate
the final portion of the presentation with
that in mind. So we took water samples, and
this just speaks to the difference of where we had a
cover crop or no cover crop, and how much water that
was left in the soil. And they found the difference
was very negligible. So to have a cover crop or not,
the water is still going to either evaporate or grow a
cover crop, so why not grow a cover crop. This is what it looked like,
made sure we covered the soil, and that should wrap that up. And I wanted to show– Yeah, give them an orientation
to the site here, and so everybody can find their
way back there. Yeah, I just wanted to give
them a quick look at this cover crop calculator. You can put in your future
species, and then it shows you your carbon-nitrogen
ratio depending on the maturity stage. How suitable it would be for
grazing, et cetera, gives you an idea of pounds per
acre, cost per acre, that sort of thing. So it’s a really handy tool to
use when you’re looking at developing a mix. Very nice. Greencoverseed.com. Now, one more question came in,
and I don’t think we can really do it justice. But for the 300 plus people
who’ve tuned into this, I think it’s a very interesting
situation that we’re all dealing with. While we can clearly see the
advantage of cover crops and soil health and many other goals
and purposes that the cover crops are serving, we know
that it’s still a very small percentage of farmers
using cover crops. So what can we do? What kind of effective
strategies can we develop to demonstrate, to show farmers, to
help them begin adoption in a big way, so that we can really
get through to the majority of farmers
in short order? This is something that we’re all
facing in various parts of the country. I think the key to that
is to start small. We work with our producers, and
we come up with some of these ideas for purposes for
cover crops or mixes, and we have them start small, in
however many acres they can feel comfortable with taking a
risk of spending the money and the time to plant
these mixtures. And then see how they work, and
things that don’t work, we learn from just as much of
the things that do work. But we tell them, don’t do
this on your whole farm. Pick a field, see how it works,
get things figured out before you would move on to
do it more extensively. So for farmers to experiment,
and then have tours or demonstrations where that
information can be shared, has been very effective. And eventually, producers will
do it on more and more acres. OK, very good, and we appreciate
this presentation this afternoon very much. Thank you very much, Jon,
and thank you all for tuning in today.

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