INSTRUCTOR: We're going to talk a little bit
about what is soil health at the beginning
and how we might help improve it or maintain it in our pasture
settings.
One of the things I would say right off
the bat is if I were to go back through each
of the presentations you've seen already and pulled out what
their best management tip was from each
of those different presentations,
it would make mine [LAUGHS] because that's
the way we maintain healthy systems,
is to be managing our fertilizer and our water
and our weeds and our other inputs
and pressures on the system effectively.
But I wanted to put it more in the context
of a holistic view of what soil health is here for you.
Sometimes it's easier for us to visualize, anyway,
from a visual point of view what soil health is not.
Typical signs of ill health in a soil system
would be runoff, where we're not, at least by design,
overirrigating our field typically,
or compacted areas or bare ground,
often which would allow for the invasion of weedy species,
as we've heard previously in some of the presentations,
and then just an observation of reduced production
or stand life over what we might expect
from a particular pasture planting.
Would all be things that we can more easily observe and see
that would indicate that the system is not really
as healthy as it ought to be.
My colleagues are going to give me a bad time
because my favorite topic is soil salinity,
and I neglected to include that here.
If we see signs of salt deposits or crusts
forming at the surface of the soil and things like that,
it would also be an indicator of reduced soil
health in those conditions.
Good soil health is often a lot more difficult
to, quote unquote, "see" because it requires some measurement.
It requires us to get in and take a look at the soil itself
to analyze for things like good aggregation and stability
of those aggregates or either maintained or increased
organic matter content, microbial diversity.
We had some folks asking about biological testing and things
like that.
Those would be indicators that the system
is actually in good health or improving in health that we
can actually measure.
And it requires us to go out and take samples and take
a look at what's actually happening in the matrix itself.
But other things that we would note in a healthy system
is that we have better nutrient cycling and availability
and longer stand life and productivity as we go along.
So what I thought I would do is rather than focus
on the measurements themselves and how
we go about sampling for them and so forth
and monitoring them, I thought about,
what are the real practical aspects
of doing what we can to maintain or improve soil
health in pasture settings?
So I'm going to cover each of these in series
as we go along here.
We're going to talk about protecting and feeding
the soil biota.
We're going to talk about managing grazing intensity.
And we're going to talk about interplanting
complementary species in our pastures
to provide continuous cover and improvements
in nutrient cycling.
We're going to talk about then also proper combined fertilizer
and water management, much of what
we've heard previously just put in the context of soil health.
So let's start off with protecting and feeding
our soil biota.
Soil microbes are primarily responsible in our soils
for creating really the binders that hold our soil aggregates
together, the polysaccharides, organic acids,
and other things that are intermediate breakdown
products of the organic matter that they're
decomposing in the system.
This forms the glue that then holds our mineral soil
particles together and improves aggregate formation,
aggregate stability, opening those soils up
to allow for good water penetration and aeration.
And they're also responsible, the soil microbes
are, for cycling of our nutrients
and the transformation of those nutrients
into plant-available forms.
So breaking down the organic matter,
weathering the minerals that are in the soil,
fixing nitrogen from the atmosphere
and providing it to the plants.
STUDENT: [INAUDIBLE]
INSTRUCTOR: Thanks for mending those, folks.
Appreciate that.
So those are the things that those microbes
are responsible for.
And in order to thrive and function the way they ought to,
they need a steady supply of carbon.
They get that from the cycling of just the plant
materials at the surface of the soil or below ground with roots
as they grow and wane.
They get it from manure and urine
from the grazing animals or external sources
that we might bring in and apply.
They get it from root exudate.
That's stuff that's photosynthesized,
sugars and things that are produced
by the plant that are pushed through the plant
out into the rhizosphere.
We're going to talk about that a little bit
in the grazing section.
But these are also supplies of readily digestible carbon
that help the microbial population thrive.
It's surprising to a lot of people
to realize how populous the soil is with living, breathing
bacteria and fungi and other little creatures that
do all this work for us.
It truly is a living, breathing tissue,
billions upon billions of individual bacteria
and fungi, thousands and thousands
of different species in our soils
that do all this processing.
There are things that we can do or do do commonly that suppress
the health of those microbes.
We get into droughty or poor irrigation management
conditions, where we're underirrigating or not
supplying enough water.
Overuse of fertilizer or pesticides,
which can contribute to salt buildup,
excess salts that reduce the ability of those microbes
to thrive, pesticides that may have non-target effects
on their survival as well in soils.
And then soil compaction and reduced aeration
that just restrict the overall function of that system.
So we need to protect those.
We need to provide for them.
We need to make sure that we're getting good adequate aeration
and moisture into the system and that we
get a steady supply of carbon that comes
into those systems over time.
Maintaining a good healthy root zone,
bringing in additional sources when
needed, and, as we'll see in the grazing section,
encouraging root exudates in the rhizosphere
will move us towards a proper condition.
The second area that I wanted to talk about
was managing our grazing intensity.
Grazing is actually really good for soil health
when done properly.
The active grazing itself sends a stimulation signal
to the roots of our forage plants
and encourages the growth of the roots.
It's a response to try to repair the damage to the above ground
chute of the plant.
And then this actually increases root exudates
into the rhizosphere.
It helps to kick the microbial population
into increased activity.
We're going to get more nutrient availability.
We're going to get better cycling.
It's going to feed that top regrowth much more quickly
than it would otherwise.
So grazing, to a proper extent, is
going to actually stimulate root growth
and improve the rapidity of regrowth on our plants
in those graze situations.
The grazing animals also deposit manures,
which are sources of these readily digestible carbons that
feed the system and keep the microbial population thriving.
Excess grazing, on the other hand,
is counter to maintaining good soil health and pastures
because we get compaction, too much
wear and tear on the plants themselves.
Grazing too low to the ground actually
can stop root growth entirely in our plants in pastures.
Beyond 50% removal of the top can severely
hamper root growth in general.
And it also causes shifts in the stand mix.
If we have a mix of legumes and grasses,
for instance, some of those plants
may not be able to take excessive wear
and will wane from the mix.
Excessive waste that's deposited in intensively
grazed area can also contribute to additional salt and ammonia
burn of new regrowth.
So we would encourage in any of these settings
to employ rotational grazing strategies.
I won't go into the details of those strategies.
You can look at the USU Extension Small Pasture
Management Guide.
There are some really good ideas there,
which will help you decrease the pressure on any given
area in the pasture to allow for the good aspects of grazing
that can help maintain a healthy system.
The next area I want to talk about really
quickly is interplanting with complementary species.
As has been mentioned in the past presentations,
cool-season grasses have a bimodal growth habit,
meaning they have growth early and late
in the season in the cooler parts of the year,
with a reduction in growth during the summer.
Some of our legumes that we might
mix into pastures, alfalfa, clovers, veggies,
and other things, have been mentioned peak a little bit
later.
And they maintain production throughout the hotter parts
of the summer when the grasses are waning.
Warm-season grasses actually peak in the summer,
conversely compared to cool-season grasses.
So planting multiple complementary species
in a pasture allows for us to fill
in the gaps when some plants are not growing
as well with those that are growing better.
And that increases not only the production in the pasture,
but also keeps the root system active.
Where it might be depressed in cool-season grasses
during the summer, others can fill it
and keep that microbial activity up as well in those systems.
The ground remains well covered.
Production meets demand there.
We don't have to graze it as intensely.
Then we can rotate more freely through rotational grazing.
And legumes in the mix then also can reduce nitrogen input
requirements in general on the whole for the entire pasture,
as Dr. Yost mentioned in the fertilizer recommendations.
So let me just give you an example of some
of what I'm talking about here.
So in this first graph-- and I think maybe that blows it up
on your screen--
we can see that the dotted line are
perennial cool-season grasses.
This is ryegrass, but it's typical a cooler-season grass,
where you have a peak in the spring
and a peak in the early fall, but it
wanes a little bit in the summer,
whereas the clover that's interplanted with it
is peaking on those periods of time
when the grasses may be waning just a bit in their production.
And so we can develop strategies with mixes of various plants.
Sorry.
Go back.
Here's cool-season grass mixed with alfalfa,
the same type of condition here where we're filling in the gaps
and keeping productivity high, keeping active root
zones busy during some of the times when some of the species
may not be as performing as well.
We're going to focus just on the middle graph
of this particular figure, where you
have cool-season species of grasses mixed
with warm-seasons species of grasses,
not just clovers or alfalfa or other things like that.
So planting complementary species in a pasture
can help keep the ground covered,
keep the root zone active, keep the microbes happy,
and meet the demand for production,
allowing us to more freely rotationally graze.
The last aspect I wanted to talk about
was maintaining good fertility and water management.
These are inseparable.
It's been mentioned over and over again
that adequate moisture provides so much benefit.
Proper fertilization, as Dr. Yost mentioned,
is going to give us the proper benefit.
But we can't separate the two.
So we have to have the moisture there
to provide for the use of those nutrients that we apply.
The plant transpiration stream is really the vehicle
for nutrient uptake.
And if we're in excesses of soil moisture,
we're going to reduce aeration.
We're going to increase the chance of nitrogen loss
from volatility.
We're going to shut down root activity, especially
in legumes in anaerobic conditions,
waterlogged conditions.
We're going to get runoff that can cause erosion and nutrient
losses.
And wet soils typically are more easily compacted.
The aggregates are easily disrupted.
And if we raise the water table levels that
may be locally present, we can increase salinity buildup
in the soil as well.
So fertilizing and irrigating to me is really the key to it.
And remembering that in pastures that are healthily grazed,
we can actually recycle most of our phosphorus and potassium
through the waste of the animals and a lot of the nitrogen,
though much of that might be either vandalized or utilized
within the body of the animal.
But a great deal of that can be recycled in those systems.
So with that, I'll quit.
And any questions you might have, you can--