Range Nutrient Cycling

Dr. Walter Schacht Author

01/07/2016 Added

65 Plays

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Range Nutrient Cycling presented by Dr. Walter Schacht

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[00:00:01.294]Yeah, good afternoon.
[00:00:02.536]Somebody said, "Hello" earlier, and there were
[00:00:04.300]a few people that responded, so that was good.
[00:00:06.679](laughing)
[00:00:08.571]So, yeah, my good colleagues in the back,
[00:00:11.196]they said, "How did you get 30 minutes?"
[00:00:13.054]And I can't tell you exactly how.
[00:00:16.362]Now, Richard, I guess has told us,
[00:00:18.161]but they weren't sure if it was a
[00:00:21.040]curse or an award.
[00:00:24.929]And they didn't say whether they're cursed
[00:00:26.787]or rewarded with me talking for 30 minutes.
[00:00:29.376]We'll get into it.
[00:00:37.721]Some of you have seen this slide before, I'm certain.
[00:00:43.514]And of course with our theme
[00:00:45.268]of the opportunities and challenges
[00:00:47.870]associated with growth,
[00:00:51.491]Dr. Green has mentioned, and others many times
[00:00:54.092]that a budding challenge and an opportunity
[00:00:56.472]is to see the beef industry grow.
[00:00:58.827]Especially the cow,
[00:01:00.151]especially the cow herd.
[00:01:01.527]So not only the feeding industry with feed yards,
[00:01:04.110]feed lots, but also actually see the cow herd grow
[00:01:07.384]in Nebraska.
[00:01:09.381]And this type of slide is often referred to then,
[00:01:12.688]is Nebraska is uniquely set
[00:01:16.219]to see a growth in the cow herd
[00:01:18.784]and the feeding industry,
[00:01:20.363]because of these integration that's occuring
[00:01:24.322]in terms of corn production or grains in general.
[00:01:30.005]With that grain used in all sorts of rations,
[00:01:32.831]both in feed yards as well as supplemental feed.
[00:01:35.733]And then we have the bio refineries,
[00:01:39.529]which of course produce a bi-product
[00:01:41.363]that's used in feeding livestock,
[00:01:43.963]especially cattle in feed yards and on pasture.
[00:01:47.094]And then of course 50% or more of the state
[00:01:50.273]is in grasslands and ranchlands,
[00:01:52.131]high quality fords production.
[00:01:55.348]So the integration of these things can be seen
[00:01:58.134]as growing the base
[00:02:02.001]for growing a cow herd.
[00:02:04.485]And then, intertwined in all this
[00:02:06.784]is that obviously with growing a lot of corn
[00:02:09.640]there's a lot of stock residue
[00:02:11.264]and someone recently did a survey
[00:02:14.840]of corn fields in Nebraska
[00:02:17.697]and reported that as little as 20-25%
[00:02:21.504]of the stock fields in Nebraska that are
[00:02:23.780]available for dormant season growing
[00:02:25.904]are actually being grazed.
[00:02:28.642]So, that leaves a lot of potential for growth
[00:02:31.382]in terms of dormant season roughage.
[00:02:34.356]And of course not all of this roughage
[00:02:37.664]and stock fields would be grazed.
[00:02:41.077]Lot of it is baled and then fed in pens
[00:02:43.724]or dry lots during the dormant season
[00:02:46.579]to cows or growing animals.
[00:02:49.644]And then Roger reported earlier
[00:02:51.943]on cover crops, and then using those cover crops
[00:02:55.298]as a feed resource or forage
[00:02:58.839]for growing animals or for cows
[00:03:01.462]during the dormant season,
[00:03:03.017]especially in that early fall to early dormant season
[00:03:07.337]period or early winter period.
[00:03:09.917]So, what we're seeing is that with this integration
[00:03:13.675]we're getting more and more roughages, forages
[00:03:17.957]available for grazing or feeding livestock
[00:03:21.094]during the dormant season,
[00:03:22.777]but we're not seeing much relative to the growing season.
[00:03:26.698]And so with this increase in availability and use
[00:03:30.903]of roughages and forages during
[00:03:32.899]the dormant season with increased
[00:03:37.983]stocking rates or increased cattle numbers
[00:03:41.279]that may result
[00:03:43.026]then what happens to our forage resources,
[00:03:45.662]to our grazing lands during the growing season.
[00:03:50.093]Or what typically look at as the grazing season,
[00:03:52.624]from sometime in May to sometime in October.
[00:03:57.953]And of course many of you have seen these figures, too,
[00:04:00.530]maps from an article published in
[00:04:04.516]2011, I believe,
[00:04:08.335]or 2013 that shows the increase conversion of grasslands
[00:04:11.829]to croplands that occurred in the late,
[00:04:17.289]around 2006-2011.
[00:04:20.002]So, not only are we seeing increased cattle numbers
[00:04:23.253]potentially, but also fewer acres of grasslands
[00:04:27.160]to support that during the growing season.
[00:04:31.458]So, what can we do if we do increase the cow herd?
[00:04:34.362]Because of that increased forage availability,
[00:04:36.800]roughage availability during the winter?
[00:04:40.501]So, we are going to look at increased stocking rate,
[00:04:45.490]and simply overgraze during the growing season,
[00:04:48.282]or do we look at increased forage production?
[00:04:52.856]With the grasslands that we have, do we provide inputs
[00:04:55.340]that then increase forage production?
[00:04:58.289]Or do we look at increased harvest efficiency?
[00:05:01.249]Harvesting a higher percent of what's available.
[00:05:06.925]And of course, especially in eastern Nebraska,
[00:05:09.538]on some sub-humid grasslands,
[00:05:12.910]there is opportunity to increase production
[00:05:16.554]because grass breeders continue to produce more,
[00:05:20.559]develop grass varieties
[00:05:23.415]that have increased production potential.
[00:05:27.222]So we can use them.
[00:05:29.115]And such inputs as fertilization has long been documented
[00:05:32.585]will increase forage production.
[00:05:37.124]And then on these eastern Nebraska pastures,
[00:05:40.132]we can look at increased efficiency of use
[00:05:43.812]of what's available,
[00:05:45.704]so we can look at higher stocking rates
[00:05:48.769]because we have simple plant communities
[00:05:51.311]very often dominated by grass like
[00:05:54.283]smooth brome grass.
[00:05:56.489]Those grasses grow rapidly following
[00:06:00.491]defoliation, because there is good soil moisture,
[00:06:02.909]good nutrient availability,
[00:06:05.474]and these are plant types that can tolerate stresses,
[00:06:09.688]especially tolerate high defoliation levels.
[00:06:13.032]So with more efficient use of these grasslands
[00:06:16.689]we can increase the percent that can be defoliated
[00:06:21.286]or grazed during that growing season.
[00:06:25.356]'Course we've moved further west into semi-arid rangelands
[00:06:28.506]like in central and western Nebraska.
[00:06:30.538]These higher stocking rates more efficient use
[00:06:34.043]become much more challenging
[00:06:35.924]because we're dealing with more complex
[00:06:39.327]plant communities and ecological sites.
[00:06:42.008]These are plants that are less responsive to inputs
[00:06:45.607]and then you've got complex plants communities,
[00:06:49.345]so each plant species responds differently
[00:06:52.026]to those inputs.
[00:06:53.489]And overall this system is less tolerant to grazing.
[00:06:56.624]So increasing efficiency, harvest efficiency
[00:06:59.072]and ranglands, semi-arid rangelands
[00:07:01.348]may be more of issue.
[00:07:05.039]But let's just focus on eastern Nebraska pasture
[00:07:09.990]and irrigated pasture, and sub-irrigated pastures
[00:07:14.792]like we have along the Platte River, or in the
[00:07:18.031]sub-irrigated meadows of the Sandhills.
[00:07:22.347]Oops.
[00:07:24.885]So we have a couple
[00:07:27.046]yearlings grazing pastures, sub-irrigated meadow pasture
[00:07:29.742]in the Sandhills,
[00:07:31.263]and what do you notice about.
[00:07:34.758]This would be late June, early July,
[00:07:36.846]these are mostly perennial cool season grasses.
[00:07:39.435]And what do you notice?
[00:07:41.292]What things pop out at you?
[00:07:45.327]It's the patchiness, right?
[00:07:46.818]So, cattle, when they are allowed to select,
[00:07:49.418]when they have more grass than what they need,
[00:07:56.238]they're gonna graze certain areas,
[00:07:57.616]return to those areas as fast as that grass grows
[00:08:00.755]because it's high in nutrient content.
[00:08:03.221]Whereas these areas that have not been grazed previously
[00:08:06.343]and those plants go reproductive,
[00:08:08.305]they get stemmy, they become less palette-able,
[00:08:11.973]lower nutrient density.
[00:08:14.493]And so we get this patchiness which results in what?
[00:08:18.972]Low harvest efficiency.
[00:08:20.317]So from a production perspective,
[00:08:21.989]from Ag production perspective,
[00:08:23.753]all of this is waste.
[00:08:25.693]Wasted, right?
[00:08:27.074]So, we're looking to get a higher percent
[00:08:29.709]of what's available consumed by the animals.
[00:08:32.224]So, how do we do that?
[00:08:34.175]Well, this is probly more of the situation
[00:08:36.334]that a lot of producers like to see
[00:08:38.807]is an evenly grazed area
[00:08:42.705]that there is not that standing material
[00:08:45.761]that's not being utilized, and therefore you should
[00:08:48.419]have a higher harvest efficiency which means
[00:08:50.834]potentially a higher gain per acre, right?
[00:08:55.173]So if we look at this figure, then we've got
[00:08:58.170]improved grazing distribution, so a higher percent
[00:09:00.828]of what's available's being grazed means
[00:09:03.290]then you have increased
[00:09:05.484]harvest efficiency, right?
[00:09:07.864]A higher percent of what's available's being consumed,
[00:09:10.348]which then results in increased carrying capacity,
[00:09:13.761]which leads to, if that's what you want,
[00:09:15.979]higher stocking rates,
[00:09:17.406]higher production per acre.
[00:09:19.519](mumbles)
[00:09:22.532]So how do we do this?
[00:09:24.047]This has been looked at for decades.
[00:09:26.647]There's many options,
[00:09:28.702]of course location of water is a key.
[00:09:32.080]Most grazing animals are central placed foragers,
[00:09:35.644]and so the center of their universe is water,
[00:09:37.954]so making water readily available
[00:09:39.974]certainly affects how animals
[00:09:41.693]distribute across the landscape.
[00:09:44.293]And there are other tools that can be used
[00:09:47.590]to affect distribution,
[00:09:50.910]but I'm here to talk about grazing management.
[00:09:55.495]So, just real quickly, how do we look at
[00:09:59.872]in that distribution of grazing,
[00:10:01.857]and how can grazing management influence
[00:10:04.016]that distribution of grazing
[00:10:05.352]in how evenly a forage resource is used.
[00:10:08.905]So, most people probly think of grazing
[00:10:12.209]in one context and one context only,
[00:10:15.076]especially those that don't understand grazing,
[00:10:17.155]or against grazing is that
[00:10:19.848]we have cattle spread across a pasture,
[00:10:22.796]they graze the entire area for the five month
[00:10:24.968]grazing season, they select areas
[00:10:27.916]that are favorable to them,
[00:10:29.739]and they overgraze it.
[00:10:32.863]But actually, in these situations,
[00:10:34.869]boy I can't stop hittin' that.
[00:10:36.681]In these situations, then on the top figure,
[00:10:39.339]the cattle are selectively grazing,
[00:10:42.764]they have ready access to that entire pasture
[00:10:46.967]for the five month growing season, let's say, okay?
[00:10:50.519]So it becomes spotty, low harvest efficiency.
[00:10:55.177]So when it's done, in the lower cartoon there then,
[00:10:59.767]concentrate the animals in 1/4 of the area,
[00:11:02.657]and they stay in each pasture for 37-38 days,
[00:11:05.559]something like that.
[00:11:06.723]Divide 150 by 4 pastures,
[00:11:10.659]and so they become more concentrated
[00:11:13.826]in 1/4 of the area
[00:11:15.614]at each pasture
[00:11:18.946]over the entire grazing season.
[00:11:22.150]And if we go ahead and get
[00:11:24.216]a little bit more intense in our management,
[00:11:27.327]we put 16 pastures now in that same management unit,
[00:11:30.868]we concentrate the animals in each one of the pastures,
[00:11:34.688]and now they're going to move
[00:11:37.427]every 10 days or so.
[00:11:39.493]They're more concentrated,
[00:11:42.419]the area within each one of the pastures
[00:11:44.939]is likely going to be less diverse
[00:11:48.270]in terms of species growing, in terms of topography
[00:11:52.882]and so forth.
[00:11:53.586]So those animals within pasture are gonna be
[00:11:55.619]more evenly distributed,
[00:11:57.163]and as they move from pasture to pasture,
[00:11:59.683]stocking density or grazing pressure is
[00:12:01.980]going to be higher, and likely the whole unit
[00:12:05.892]is going to be used more evenly.
[00:12:09.085]And if you get all the way
[00:12:10.130]to a 50 pasture system,
[00:12:11.662]they're moving every three days.
[00:12:13.391]Higher density, higher grazing pressure.
[00:12:15.829]Area within each pasture's more similar,
[00:12:18.465]and therefore, there's more uniformity
[00:12:21.565]in distribution.
[00:12:25.870]So, how does this distribution affect
[00:12:29.853]the different components of grazingland systems?
[00:12:34.939]So, we've been this group then, since
[00:12:38.038]2010 and before,
[00:12:39.791]we've been looking at some critical component areas,
[00:12:43.517]what's the aboveground production,
[00:12:45.479]botanical composition and the response to these
[00:12:47.813]different grazing strategies
[00:12:50.192]in trying to increase efficiency of use.
[00:12:54.569]What's the utilization of that aboveground biomass?
[00:12:56.948]What's the animal performance and production
[00:12:58.829]in response to this increased management intensity?
[00:13:01.906]And then, what's the rates in decomposition,
[00:13:04.668]and incorporation at these different nutrient pulses.
[00:13:09.988]Because if cattle are only in a pasture for three days,
[00:13:12.911]their affect on that system is during that three day period,
[00:13:16.208]mkay.
[00:13:17.289]So all of that pulse of nutrients and interactions
[00:13:23.621]in that continuum of livestock.
[00:13:25.820]Dung, urine, and soil,
[00:13:29.397]is all being affected by those pulses, 'kay?
[00:13:33.703]Rather than just a continued long stocking
[00:13:37.383]during the entire 150 days on the entire area
[00:13:41.028]at one time.
[00:13:42.305]And then, as a result, what's the nutrient use efficiency?
[00:13:49.463]So these are the group of scientists that are working
[00:13:53.647]on these questions and as Richard said across many
[00:13:59.041]departments and a number of disciplines within
[00:14:02.226]the department Agronomy and Horticulture.
[00:14:05.105]And this research we're doing
[00:14:06.986]at the Barta Brothers Ranch.
[00:14:08.901]And as you would all expect, a lot of graduate students,
[00:14:12.465]undergraduate students, technicians involved
[00:14:14.949]as well.
[00:14:18.009]This research being conducted at the Barta Brothers Ranch
[00:14:20.533]which is
[00:14:21.811]a University of Nebraska Foundation Property,
[00:14:24.748]south of Bassett
[00:14:26.594]in the eastern Sandhills
[00:14:28.614]and this research is being done
[00:14:30.517]on sub-irrigated meadow.
[00:14:31.992]So not on the typical upland range lands
[00:14:35.057]that you commonly think of in the Sandhills,
[00:14:36.902]but sub-irrigated meadow that's more
[00:14:39.956]similar to what we would have
[00:14:42.439]here in eastern Nebraska
[00:14:44.135]under well watered conditions.
[00:14:48.348]So, quickly, this grazing strategies that
[00:14:51.843]we're comparing, then,
[00:14:53.654]is something that's called mob grazing,
[00:14:56.080]which is ultra-high stocking densities.
[00:14:58.495]So, instead of 4-5 animals per acre,
[00:15:01.920]we're at any point in time we're talking 200 plus.
[00:15:05.437]And in order to get that level of stocking density
[00:15:08.757]and grazing pressure, those animals are being moved
[00:15:11.683]on a half day basis.
[00:15:13.819]So, our graduate students, technicians then,
[00:15:16.779]are moving them across
[00:15:20.876]a sub-irrigated meadow
[00:15:22.445]every half day with electric fence,
[00:15:24.964]to get very high stocking densities
[00:15:27.029]or grazing pressure at any
[00:15:28.991]point in time.
[00:15:33.393]And then the two conventional grazing strategies
[00:15:37.815]are two four pasture systems.
[00:15:40.032]One involves a four pasture
[00:15:43.456]over a 60 day period, so each
[00:15:46.752]of the quarter areas are being grazed
[00:15:48.402]for 15 days, and then the cattle moved on.
[00:15:51.374]The first one is a once over system
[00:15:54.938]that the second one is a twice over system,
[00:15:57.700]so the rate of movement is quicker,
[00:15:59.733]and they move through the four pastures twice
[00:16:02.042]during the 60-80 day grazing period.
[00:16:05.340]And then we have a continuous stocked treatment
[00:16:07.940]where the cattle go on to the one pasture
[00:16:10.332]and they stay in it during the entire grazing season.
[00:16:13.454]Meadows in the Sandhills are commonly used
[00:16:16.294]as hayland, and so we do have the
[00:16:18.739]traditional hay treatment along with a no harvest control.
[00:16:25.492]And then also our funding sources have been
[00:16:29.083]three or four USDA grants
[00:16:31.637]and then University of Nebraska foundation support,
[00:16:35.503]and so we also are doing much of this research
[00:16:38.277]on ranches,
[00:16:39.624]and this is a ranch south of Johnstown
[00:16:42.096]on sub-irrigated meadow
[00:16:43.942]and you can see the density of livestock,
[00:16:45.742]I mean this is it.
[00:16:47.355]They're at about 800 animals per acre,
[00:16:51.001]and so they're moving seven or eight times per day
[00:16:54.924]in order to keep enough forage available
[00:16:56.851]to the cattle as they move across this meadow.
[00:17:02.679]So, the purpose then with these ultra-high stocking
[00:17:04.804]densities from a advocate
[00:17:07.625]consultant perspective
[00:17:10.004]is to attempt to speed up the rate of nutrient
[00:17:13.882]cycling, we'll talk about that in a minute,
[00:17:15.983]and then therefore get more organic matters,
[00:17:19.361]more total carbon into the soil,
[00:17:21.625]and build in the depth,
[00:17:24.701]the structure, the water holding capacity,
[00:17:26.721]the fertility of the soils,
[00:17:28.846]therefore grow more grass in the long term, right?
[00:17:31.608]And then there's other things in terms of
[00:17:33.965]the evenness of fecal and urine deposition
[00:17:36.438]and increase pasture productivity and increased
[00:17:40.745]animal production and performance.
[00:17:45.955]'Course with that many animals per unit area,
[00:17:48.233]there's a lot of trampling.
[00:17:49.777]Okay, so when we talk about utilization,
[00:17:52.261]there's two components of utilization
[00:17:53.852]from the plant perspective, right?
[00:17:55.721]Plants are either with cattle, grazing them.
[00:17:58.762]They're generally either consumed,
[00:18:00.435]or they're trampled.
[00:18:01.955]And so, very often you have high stocking densities,
[00:18:05.776]a high percent of what's available
[00:18:08.467]is trampled.
[00:18:11.219]So there's kind of an antagonistic thing
[00:18:13.599]going on here.
[00:18:14.760]As you increase grazing pressure,
[00:18:16.525]as you increase
[00:18:18.972]the management intensity of grazing,
[00:18:21.317]then is the animal gonna trample it,
[00:18:23.801]or is it going to consume it?
[00:18:25.990]And so it's a fine line.
[00:18:28.351]Obviously most people are after high
[00:18:30.408]harvest efficiency, so they want the animals
[00:18:32.485]to consume it.
[00:18:33.970]But at the same time they want it trampled
[00:18:35.805]so that that plant material is getting into the soil
[00:18:39.624]and being more rapidly decomposed.
[00:18:44.221]But, we've found a lot of trampling.
[00:18:46.148]So this research, like I said, those of you that have
[00:18:48.528]been to Barta Brothers Ranch,
[00:18:49.933]it's just on the meadow, 80 acre meadow
[00:18:53.139]west of the house and lab
[00:18:55.098]there at the Barta Brothers Ranch.
[00:18:58.957]Dr. Belsky and I started this research
[00:19:01.204]at this sight in 2010,
[00:19:03.189]and then with additional support we've been able
[00:19:05.429]to expand it into things like nutrient cycling.
[00:19:12.148]So, to this point, just to give you a summary
[00:19:14.671]of what we're finding,
[00:19:16.052]we want to conduct this study
[00:19:18.397]through 2018,
[00:19:21.577]so have a eight year study.
[00:19:25.003]But in the first four years of study
[00:19:27.324]what we've found is, this more management
[00:19:29.658]intensive grazing has not influenced
[00:19:32.396]plant production or species composition.
[00:19:35.787]So even with this higher intensity of management,
[00:19:39.282]we're still getting the same level of production
[00:19:41.731]in terms of plant production,
[00:19:43.565]and botanical composition has not changed.
[00:19:48.416]And, pretty much the same
[00:19:49.590]on private ranches.
[00:19:52.411]So here we have a ranch that's been
[00:19:54.768]practicing mob grazing, started in 2004,
[00:19:57.984]so this was about 10 years after
[00:19:59.830]he initiated mob grazing,
[00:20:01.931]and what this compares
[00:20:04.311]is the production of the grass annually,
[00:20:07.851]or of the vegetation cover
[00:20:10.312]in a meadow that's mob grazed,
[00:20:13.586]versus an adjacent meadow
[00:20:16.547]that is simply being hayed each year.
[00:20:19.042]So the mob grazing has not resulted
[00:20:21.643]in any increase or decrease in terms of the production.
[00:20:24.824]I see that the whole legend isn't here,
[00:20:28.109]but the gray is the cool season grasses.
[00:20:32.126]The brown are sedges.
[00:20:35.434]Grazing tends to favor
[00:20:37.849]increase in cool season grasses on these meadows.
[00:20:42.929]And in terms of utilization, what percent
[00:20:45.488]of what's available is actually consumed
[00:20:47.855]by the grazing animal?
[00:20:49.493]Again these are on three of the Sandhills ranches
[00:20:52.337]that we work with, and the green bar
[00:20:55.355]is the amount of standing crop
[00:21:01.724]prior to grazing.
[00:21:03.657]And so we have a lot of graduate students,
[00:21:05.868]undergraduate students
[00:21:06.925]and technicians that go out,
[00:21:08.422]they clip, immediately before cattle are moved
[00:21:11.371]into a strip.
[00:21:12.799]They graze for a half a day, quarter day,
[00:21:15.539]whatever the case may be.
[00:21:17.221]Students go back in then and clip
[00:21:19.160]immediately after it's been grazed.
[00:21:21.378]And what they find is about 6-11%
[00:21:25.255]of the standing forage is still intact
[00:21:28.018]and remains after the grazing.
[00:21:29.817]So this is severe grazing.
[00:21:34.360]And then, anywhere from
[00:21:36.772]46 up to 61% is trampled,
[00:21:39.720]which means about 40-50% is actually consumed.
[00:21:43.574]So a harvest efficiency of 50-60%
[00:21:46.732]on many of our grazing systems,
[00:21:49.170]we're talking about harvest efficiencies
[00:21:51.096]of 25-30%.
[00:21:52.932]So a greater percent of intake is possible
[00:21:57.598]with more intensity of management,
[00:22:00.454]of course that's why it's done, right,
[00:22:02.230]from a economic perspective.
[00:22:06.616]So then the next question was then,
[00:22:08.684]by drawing the larger team together was,
[00:22:12.306]what's happening in terms of nutrient cycling?
[00:22:18.463]I started off talking about efficiency of use,
[00:22:20.770]of forage resources on range and pasture,
[00:22:23.614]and whether it can support
[00:22:25.808]increase in the cow herd, right.
[00:22:28.454]But, what we also want to see
[00:22:31.833]is what happens to the system.
[00:22:33.911]If we do move to these higher
[00:22:37.116]harvest efficiency systems,
[00:22:38.763]how does that influence the nutrient cycling
[00:22:43.393]and nitrogen and carbon pools and so forth
[00:22:45.345]in the system.
[00:22:46.936]So, probly when people generally think
[00:22:50.083]about grazing on grazing lands,
[00:22:54.215]we look at this nutrient cycling that's spatially coupled.
[00:23:00.098]So, nutrients in the soil are taken up by plants.
[00:23:04.268]The cattle graze the plants, they pass on the nutrients.
[00:23:08.703]The cattle are
[00:23:13.035]defecating and urinating
[00:23:15.295]and so that nutrient pool is returning to the soil
[00:23:19.376]and so goes the cycle, right?
[00:23:21.617]There's some deviations in terms of
[00:23:23.475]atmosphere and so forth,
[00:23:24.855]but basically we think of it that way, right?
[00:23:28.036]So we've got the cattle out there grazing
[00:23:30.092]and their eating and poopin' and peein'
[00:23:32.530]and doin' their thing across the landscape.
[00:23:36.707]And we tend to think it's all fairly even spatially
[00:23:39.644]and temporally.
[00:23:42.880]But actually, we're proposing then, and observation
[00:23:45.715]would indicate though, that there's decoupling going on,
[00:23:49.256]right?
[00:23:49.988]That cattle tend to graze in places
[00:23:53.471]they don't hang around or loaf around
[00:23:55.815]like around water or salt locations,
[00:23:58.156]and that's where they're actually doin' a lot of
[00:24:00.373]defecation and urination, is in these concentrated areas.
[00:24:04.099]So spatially then, that soil pool isn't necessarily
[00:24:08.829]being taken up by the plant pool across
[00:24:11.738]the pasture as a whole
[00:24:13.352]because the nutrients are being concentrated
[00:24:15.488]around favorite locations, and so we get
[00:24:20.423]a nutrient loading in partial parts of the pastures.
[00:24:29.221]So with the current study we're focusing
[00:24:32.042]right now on dung
[00:24:34.549]and how do we characterize the fate
[00:24:37.800]of nutrients from dung,
[00:24:39.762]and so specifically, this past two years
[00:24:42.989]in 2014 and 2015, we got a team of
[00:24:46.287]people looking at what is the fate of
[00:24:48.608]nitrogen, carbon and phosphorus
[00:24:50.245]during decomposition.
[00:24:51.743]How much of it is lost via gaseous emissions.
[00:24:55.608]'Course much is that is returned back
[00:24:58.546]to the pasture land.
[00:25:00.728]But what is being incorporated in the soil?
[00:25:03.026]How does the process vary over time
[00:25:04.919]through the growing season?
[00:25:07.578]And then we have an entomologist, Jeff Bradshaw,
[00:25:10.967]working with us from the panhandle,
[00:25:13.103]and he's asking questions about how dung beetles,
[00:25:15.959]dung beetles are quite common in the Sandhills,
[00:25:18.502]found I think 13 different species of dung beetles
[00:25:21.857]active in the meadow we're working on.
[00:25:25.385]And then how does weather interact with
[00:25:27.638]these questions about nutrients and dung.
[00:25:33.603]Yeah, here's a few dung beetles, right?
[00:25:37.776]Yeah.
[00:25:38.611]It's a fascinating story, but I'll just show
[00:25:40.453]that there are dung beetles.
[00:25:43.751]And so, to talk through the methodology of course
[00:25:46.478]would take some time and somebody with more
[00:25:48.672]knowledge of it than I have, but,
[00:25:50.530]of course Martha Mamot and Anna Win-Gaw-Er,
[00:25:55.084]our former post-doc worked and set up most of this.
[00:26:00.998]But we have a couple of graduate students then,
[00:26:04.060]on the meadow they have collected, each year,
[00:26:07.333]they collect a lot of crap from cattle
[00:26:09.946]that are on a forage diet,
[00:26:12.709]and then they,
[00:26:15.425]in a experimental setup here,
[00:26:19.453]they distribute that dung in blocks,
[00:26:22.750]and then they make that dung pat
[00:26:26.187]either open and available for dung beetle colonization,
[00:26:29.785]or they cover it with screening to keep
[00:26:31.968]the dung beetles out,
[00:26:33.663]and then we have patches or blocks that have
[00:26:36.890]no dung on them at all.
[00:26:38.887]And then this laying out of the dung
[00:26:42.068]is done twice, once in mid-June, once in mid-July,
[00:26:45.725]and then those dung pats are followed
[00:26:48.348]and data collected from them over a two month period
[00:26:52.806]in both cases.
[00:26:57.342]Since you're all kinda serious here,
[00:27:00.131]everybody
[00:27:02.388]has to have a pun or something, you know,
[00:27:04.146]it's a crappy job, right?
[00:27:06.026]Yeah, anyway.
[00:27:10.838]Very briefly, what we found so far is that,
[00:27:14.176]this is the 2014 data, is that
[00:27:19.015]what's happening with nutrients, with nitrogen
[00:27:22.058]and carbon in the dung pats,
[00:27:26.567]and is there a difference between those
[00:27:28.289]dung pats that are colonized by dung beetles
[00:27:30.904]and those that are not.
[00:27:32.697]Very briefly, so far, whether we're talkin' about
[00:27:35.571]gas emissions, concentrations of nutrients in the soil
[00:27:39.948]or concentration of nutrients in dung,
[00:27:42.397]is there hasn't been differences between dung beetles,
[00:27:47.375]colonized dung pats and non-colonized dung pats.
[00:27:53.357]So that the amount of methane being emmitted
[00:27:56.885]from those two different kinds of pats
[00:27:59.126]has not differed
[00:28:02.068]in terms of soil, ammonium nitrate,
[00:28:04.918]there were nitrogen contents have not differed,
[00:28:07.531]and in terms of concentrations of ammonium nitrogen
[00:28:11.710]has not differed in the dung, okay.
[00:28:14.752]Certainly different in terms of the soil concentration
[00:28:19.314]of nutrients below dung pats than out in the open,
[00:28:23.307]but we're not seeing a beetle effect so far.
[00:28:30.810]And of course we are,
[00:28:32.387]members of our group are collecting dung beetles
[00:28:35.358]and using pitfall traps.
[00:28:39.680]And of course, anybody know what the bait is
[00:28:41.185]in these pitfall,
[00:28:42.346]'cause you know you'd just have these
[00:28:43.902]little holes set out in pastures
[00:28:46.305]and then the dung beetles are just walkin' along
[00:28:48.545]and they fall in the trap, right?
[00:28:50.124]Then they're asphyxiated
[00:28:51.784]in basically this is antifreeze,
[00:28:56.045]but do you know what attracts them to that trap?
[00:28:58.924]Chimp poop.
[00:29:00.224]So our entomologist from Scottsbluff,
[00:29:02.580]so he goes to the Scottsbluff Zoo
[00:29:04.659]and gets a order of chimpanzee poop,
[00:29:08.083]because it really gets the dung beetles going,
[00:29:11.066]so it's a way to
[00:29:12.204](crowd laughing)
[00:29:13.504]collect dung beetles
[00:29:14.824]on these different treatments to see
[00:29:16.523]where they're the most active.
[00:29:20.024]Interestingly though, we thought perhaps
[00:29:22.137]we had hypothesized we'd see the greatest
[00:29:24.237]density of dung beetles on the mob grazed areas
[00:29:28.219]because there's that spatially and temporally
[00:29:30.414]a consistent supply of dung,
[00:29:32.329]but we haven't seen a difference in diversity
[00:29:35.567]as far as the diversity index
[00:29:40.046]with a difference between mob grazed
[00:29:41.779]and the conventionally grazed pastures, okay.
[00:29:44.380]So the beetles aren't exactly responding
[00:29:46.725]as we thought they might be.
[00:29:50.178]So, with this baseline information relative to
[00:29:56.254]dung decomposition, nutrient release into the soil,
[00:30:00.086]nutrient concentration in the soil,
[00:30:02.037]we then want to take that out to the pasture
[00:30:06.065]level and so we want to see then
[00:30:09.954]how do grazing strategies impact
[00:30:13.625]the temporal and spatial
[00:30:15.001]distribution of the renewed nutrient pools.
[00:30:20.026]So, in a
[00:30:23.586]high density, high stocking density area
[00:30:27.411]within a management unit,
[00:30:29.531]there should be more even distribution of dung piles,
[00:30:33.778]dung pats, and urine spots.
[00:30:36.663]Because the animals are more evenly distributed,
[00:30:39.356]whereas in a continuously stocked pasture,
[00:30:41.325]at the other extreme, the cattle tend to
[00:30:42.816]hang out in their favorite places,
[00:30:45.288]and then the dung pats, urine spots
[00:30:47.285]are located around those areas.
[00:30:49.805]So, since we know then, we're learning
[00:30:52.683]more of the dynamics of nutrient cycling
[00:30:55.946]with static dung pats.
[00:30:58.684]What happens then, out in a pasture?
[00:31:00.751]How does this impact nutrient cycling
[00:31:03.085]if we have those dung pats more evenly distributed,
[00:31:07.229]versus them congregated, concentrated in
[00:31:11.280]favored areas of the cattle.
[00:31:13.751]And so yes, we're using UADs too, and Richard Ferguson
[00:31:18.165]as you saw is part of this study,
[00:31:20.452]and so started late last summer
[00:31:24.236]in using UADs or drones to map out the location
[00:31:29.215]of dung pats and urine spots
[00:31:31.515]on these different types of pastures.
[00:31:34.197]And so then our goal is to quantify
[00:31:36.994]potential at the pasture level
[00:31:39.468]of soil nitrogen mineralization,
[00:31:41.673]carbon storage, phosphorus availability
[00:31:43.647]and so forth is our goal there,
[00:31:46.885]here in the next year.
[00:31:50.020]And eventually then, Hy-Shun-Es is the modeler on the team,
[00:31:54.974]then there will be a modeling exercises
[00:31:59.255]to develop the explanations, the directions,
[00:32:04.927]the models for nutrient cycling on these pastures
[00:32:08.659]that are managed with different intensities.
[00:32:16.487]So, in the end, can we use our pastures
[00:32:20.650]more efficiently to not only
[00:32:25.506]to increase the efficient use of the forage resource,
[00:32:28.545]but how does that affect long term production
[00:32:30.426]of those sights, how does it affect species composition,
[00:32:33.363]what's happening above and below ground relative
[00:32:35.846]to nutrient availability and patterns
[00:32:38.400]of availability of the nutrients
[00:32:41.570]and then can we model it?
[00:32:43.891]So that's where we are.
[00:32:47.270]Richard.
[00:32:48.512](applause)

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Range Nutrient Cycling

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