alfalfa, 1.1 others, 16.5 nutrient cycling in winter grazing cattle on … · 2020. 3. 2. ·...
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Nutrient cycling in winter grazing cattle on pasture; five years following bale grazing once. Réjean Picard, Farm Production Advisor, Manitoba Agriculture, Food and Rural Initiatives, Somerset. ([email protected])
Introduction and background: Perennial pastures are typically low in fertility which limit forage growth. On the other hand manure from livestock over wintering in confinement is
nutrient rich and expensive to apply to fields. Bale grazing forage to cattle directly on fields/pastures during the winter time offers the opportunity
to add much needed fertility to perennial pastures while reducing manure disposal costs related to over wintering cattle in confinement. Bale
grazing allows livestock to return a large proportion of the nutrients they consume directly to the landscape where they are fed. It reduces feeding
time and reduces costs normally associated with feeding livestock in confinement during the winter months. Manure and feed residue remaining
after bale grazing contain valuable nutrients that become available over time to established forage plants. This improves productivity and quality
of the forage stand.
This project started before bale grazing was applied in 2007 with funding from the Covering New Ground (CNG) program and the Pembina Valley
Conservation District (PVCD). Since 2007, various programs, including the Livestock Stewardship Initiative (LSI) and the Agricultural
Sustainability Initiative (ASI) provided funds to continue monitoring the project sites. This project was designed to measure and to monitor the soil
nutrient levels of ten differently and independently managed bale grazing sites.
Methodology:
The ten established perennial pasture sites involved in this project were initially soil sampled to a depth of 48
inches in the fall of 2007 to determine the nutrient level of each pasture before bale grazing. Each cooperator bale
grazed their herd in the fall 2007 to early winter 2008. Soil samples have been collected every fall since 2008 to
measure the nutrient level in the bale grazed zones (green spots only). Depending on the site, eight to ten core
samples are collected on a site to form a composite sample of the bale grazed areas for each sampling depth.
Bale grazed sites varied in size from 3 to 14 acres. Each site belongs to a different owner and is managed
independently from the others.
Forage samples were hand clipped in the bale grazed, green zones, and compared to samples collected in-
between or away from the bale grazed zones to compare feed quality.
All sites investigated were bale grazed once in winter 2007/08 on established perennial forage
stands. Only one of the sites was bale grazed once before while all the others were bale grazed
for the first time. Site size varied from 3 acres to 14 acres. Bale density varied from 2 to 56 bales
per acre; all round bales. 10 sites were investigated from 2007 to 2009 which dropped to 8 sites in
2010 due to a change of land management practice on two of the sites. We added the results of
another site bale grazed once in 2007/08 for consistency of sampling.
The soil samples were collected in the fall time inside the greener zone created by the bale
grazing effect.
Nitrogen, phosphorus and potassium soil nutrient levels increased dramatically in the top four feet
of the soil profile within one year after bale grazing. Since 2008, the level of nitrogen (N) declined
initially and seems to have stabilized. P and K increased for the first few years and remains
elevated but appears to have stabilized after five years of forage growth and harvest either as hay
or pasture.
Residual nitrogen appeared to be moving through the soil profile. Much of it remains within the top
four foot depth four years after bale grazing. On some sites sampled to 6 feet deep, we have
found elevated nitrate-N in the 5 and 6 foot depth of some lighter soil type sites. 2012 was below
normal for precipitation but above normal for heat units received during the growing season.
Due to the rapid increase in soil nutrients after bale grazing, bale grazing should not be done on
the same site until nutrient levels drop and forage productivity slowed. Soil testing should be done
regularly on bale grazed sites to monitor the residual nutrient levels in years following bale
grazing.
Bale grazing was considered as very beneficiary by all cooperators involved in this
project. They all continue the practice at a comparable level or on a larger scale.
Forage yield was measured on some sites in 2012. Forage yield was consistently
higher on the bale grazed areas compared to the check; average 230 % of check.
Relative dry matter (DM) yield ranged from 176% to over 281 % of the check area.
Sites with the highest bale densities had more uniform plant growth across the
pasture area.
Five years after bale grazing was applied once, forage growth is visibly higher and
darker green in the bale grazed zones compared to the check areas. Potassium
content of the forage remain elevated in plants sampled in the bale grazed, greener
zones, compared to the check. TDN and phosphorus remained almost unchanged in
the greener zones compared to the check. Crude protein of the forage sampled in
2012 have a comparable levels in both the green and check areas of the pastures.
This might be an indication that the nitrate is not accumulated to excess as it was in
the first three years post bale grazing.
Initially feed litter and manure accumulated most where a bale was grazed and
tended to delay forage re-growth the first year after bale grazing was done.
Sometimes heavy litter cover prevented plant re-growth completely but only on a very
small area. Since 2009, those heavy residue areas are not visible anymore being
completely covered by plant growth.
Little to no new weed growth appeared on the bale grazed areas after the first year of
bale grazing. Weeds already present tended to benefit from the added nutrients and
grow larger (dandelions at one site, Canada thistle at others). Year five after bale
grazing, established perennial grasses have taken over and dominate those areas.
The plant population in the green zones changed after bale grazing was applied; only
a couple of grass species (brome grass and quack grass) tend to dominate the area
bale grazed compared to a broader variety of plant species in the check areas.
Similar findings in the 2009, 2010 and 2011 surveys.
This project is funded by the Canada and Manitoba governments under Growing
Forward, a federal-provincial-territorial initiative
Clearwater 2007 The cow herd is feeding on the bales laid out.
Access to the feed is controlled by an electric
wire fence.
Clearwater site 2008;
Pasture grass re-growth after one pass grazing
was done.
Grass re-growth is limited in areas of heavier
litter accumulation.
No evidence of new weeds growing in heavy litter
areas.
Nutrients from forage fed to cattle on pasture are returned to the pasture in the form of urine,
feces and feed litter. Plant growth responds very rapidly to improved soil fertility resulting in
increased forage quantity and quality. Feed analysis results from forage samples collected on
many of the sites monitored are summarized in the graphs below. Crude protein and potassium
increased the most early after bale grazing compared to the check areas. Total Digestible
Nutrients (TDN) and phosphorus increased slightly compared to the check areas.
Plant species trends
Kentucky bluegrass,
48.7
Quackgrass, 15.8
Smooth bromegrass,
8.1
Dandelion, 6.4
Meadow bromegrass,
3.4
Alfalfa, 1.1
Others, 16.5
Plant species in non-bale grazed areas Plant species identified in bale grazed
areas
Dandelion, 1.3Meadow
bromegrass,
4.3
Kentucky
bluegrass, 8.5
Others, 2.8
Quackgrass,
49.3
Canada thistle,
4.6
Smooth
bromegrass,
29.2
On bale grazed sites, species diversity decreases
and has an average of 6 species per site.
Quackgrass was the most dominant grass or on
some sites smooth bromegrass. Kentucky
bluegrass almost disappears or becomes less
dominant after bale grazing. Canada thistle is more
prevalent on bale grazed sites (5 sites) and less
common on non-bale grazed sites (2 sites)
The non-bale grazed sites had more diversity of plant
species and were dominated by Kentucky bluegrass.
There were an average of 9 species per site
Bale grazing near Clearwater, Manitoba
Forage quality in Bale Grazing systems
Soil nutrient summary and analysis:
Forage summary and observations
Plant identification and analysis provided by
Jane Thornton, Range and Pasture specialist,
MAFRI
Soil nutrient trends
2007 site setup in Clearwater, Manitoba:
Site location Clearwater West
Area bale grazed 13 acres
# bales set out 728 large rnd
# bales /acre: 56
# heads grazed: 200
# days grazed: 150
Soil type Sandy loam
Ag Capability 4M
This site is part of a 160 acre parcel of land
subdivided into numerous paddocks for rotation
grazing in the summer time. In 2012 this site was
grazed twice, once in the spring and once in the
fall.
Table 1A- 2007-2012 Summary of soil analysis results from bale grazing
sites sampled in the Pembina and South West GO Team areas.
Fall 2012 Fall 2011 Fall 2010 Fall 2009 Fall 2008 Summer
2008
Fall 2007
Average Average Average Average Average Average Average
# sites n= 9 n=9 n=8 n=10 n=10 n=10 n=10
Nitrate-N
(inches) lbs/a lbs/a lbs/a lbs/a lbs/a lbs/a
0 to 6 45 39 37 59 97 44 11
6 to 12 18 21 24 47 120 17 11
12 to 24 48 31 89 94 173 22 15
24 to 36 38 29 85 59 57 12 11
36 to 48 38 36 68 41 32 8 9
187 156 303 300 454 101 57
Phosphate-P (ppm, depth in inches)
0 to 6 39 48 79 31 53 33 20
6 to 12 19 24
12 to 24 9 6
67 78
Potassium (lbs/a, depth in inches)
0 to 6 1820 1981 2376 2117 1969 1369 699
Sulfate-S (lbs/a, depth in
inches) lbs/a lbs/a lbs/a lbs/a lbs/a
0 to 6 81 146 65 192 127 136 225
6 to 12 326 319 292 601 334 319 644
12 to 24 1441 2128 1187 2143 1760 1389 2604
24 to 36 1602 1976 1304 2127 2086 2050 1999
36 to 48 1676 2201 1458 2120 1920 2251 1484
5126 6770 4306 7183 6227 6145 6957
Topsoil
OM (%) 6.26 5.38 5.81 7.09 6.76 5.94 6.37
Topsoil
pH 7.61 7.64 7.69 7.61 7.54 7.83 7.45
Top soil
EC
(ds/m) 0.43 0.47 0.33 0.55 0.56 0.5 0.53
57 101
454
300 303
156 187
0
100
200
300
400
500
Fall 2007 Fall 2008 Fall 2010 Fall 2012
Nitrate N average values (lbs/a) to 48 inches for 8-10 pasture sites bale grazed once in
winter 2007-08.
20
33
53
31
79
48 39
0
10
20
30
40
50
60
70
80
90
Ph
os
ph
ate
-P p
pm
Sampled date
Phosphate P average level in the topsoil of 10 bale grazed sites in the Pembina
GO Team area from 2007 to 2012.
699
1369
1969 2117
2376
1981 1820
0
500
1000
1500
2000
2500
Po
tas
siu
m lb
s/a
Sampled date
Potassium average level in the topsoil of 10 bale grazed sites in the Pembina
GO team area from 2007 to 2010.
2012 Cartwright West
site check area
2012 Cartwright West
site bale grazed area 277
228 238
281
176 182
230
0
50
100
150
200
250
300
2012 relative dry matter forage yield (bale grazed vs check, one cut only) on sites bale
grazed once in 2007.
11.5 10.3 10.6
12.3 11.4
15.8
11.1
19.0 20
18.8
0.0
5.0
10.0
15.0
20.0
25.0
2012 average
2011 average
2010 average
2009 average
2008 average
CP
%
2008-2012 average crude protein (%DM) of forage samples from sites bale grazed once in
2007.
Check
Green
59.22 61.08 59.44 61.37 60.19 59.01 60.68 62.58 62.09 61.92
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
2012 avg
2011 avg
2010 avg
2009 avg
2008 avg
TD
N (
% D
M)
2008 to 2012 TDN (%DM) content of forage samples collected from sites bale grazed
once in 2007.
Check
Green
0.23
0.27 0.24
0.28
0.23
0.27 0.25
0.36
0.32
0.27
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
2012 avg 2011 avg 2010 avg 2009 avg 2008 avg
P (
%D
M)
Phosphorus (% DM) in forage samples from bale grazed site in 2008, 2009,2010, 2011 and
2012.
Check
Green
1.96
1.61 1.35
1.95
1.42
2.78
1.90
2.77
3.35
2.33
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
2012 avg 2011 avg 2010 avg 2009 avg 2008 avg
K (
%D
M)
2008-2012 Potassium (%DM) in forage samples from sites bale grazed once
in 2007.
Check
Green
Clearwater 2012,
Still growing green
Clearwater 2011,
growing lush and green
Clearwater 2010,
abundant forage growth.