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Improving Life through Science and Technology
Grazing Down the Carbon: The Scientific Case for Grassland Restoration
Biodiversity for a Livable Climate15th November 2014
Boston
Richard Teague, Texas A&M AgriLife Research, Vernon
Overview
Need to improve ecosystem function
Big problems and big opportunities
Testing a ranch scale hypothesis
Published research results
Conclusions
Importance for climate change mitigation
Regenerative management to mitigate agriculture’s Carbon footprint
Restore Ecosystem Function
• Soil formation
• Soil retention
• Biodiversity
• Primary production
• Water cycling
• Nutrient cycling
• Habitat provision
• Fresh water
• Food, fiber
• Water purification
• Climate regulation
• Temperature moderation
• Biological control
• Soil maintenance
• Erosion control
• Flood mitigation
• Seed dispersal
• Pollination
How sustainable is current agriculture?
Modern agriculture has greatly increased human well-being and wealth
But production of food has come at considerable environmental and social cost
Negative effects include: disruption of hydrological and biogeochemical processes, soil erosion and impoverishment, excessive water use and aquifer depletion, contamination of soil and water by fertilizer and biocides, air pollution from aerosols, loss of pollinators loss of habitat and biodiversity, and increased GHG emissions
The role of forages and grazers
In contrast, ecologically sensitive, regenerative management of ruminants in crop and grazing agriculture contributes positively to critical ecosystem benefits
Conservation management measures and inclusion of perennial forages in cropping systems have been demonstrated to reduce negative impacts
My Goal
Find out : Why there is a discrepancy between some
research and rancher achievements
What is the best that management can achieve to sustain: livelihoods
delivery of ecosystem goods and services
90% of Soil function is mediated by microbes
Microbes depend on plants
So how we manage plants is critical
Indicator: Soil Temperature
At 70 oF, 100% of Soil moisture is used for growth.
At 100 oF, 85% of Soil moisture is lost and 15% is used for growth.
At 115 oF, microbes begin to breakdown, and
At 140 oF they die.
Essential Ecosystem Processes
1. Energy flow - Maximize the flow of solar energy through plants and soil.
2. Water cycle - Maximize capture and cycling of water through plants and soil. Reduce export and import.
3. Mineral cycle - Maximize cycling of nutrients through plants and soil.
4. Community dynamics - High ecosystem biodiversity with more complex mixtures and combinations of desirable plant species leads to increased resilience and productivity.
Improving Rangeland Soil Health
Improve soil microbe function by:
• Improving plant cover• Perennial plants rather than annuals
• Manage for most productive plants
• Leave adequate plant residue
• Minimizing bare ground - plant and litter cover
• Grow plants for as many months each year as possible
Edwards Plateau Ranch 3-D View w/ GPS Locations
1. 39% area used
2. 41% GPS points on 9% area
3. SR: 21 ac/cow
4. Effective SR: 9 ac/cow
Grazing PatternNovember to March < 10
10-50
50-150
> 150
Days present
Water point
Senft et al. 1985320 acres10-12 stockers
Planned multi-paddock grazing
Manager can control: How much is grazed The period of grazing, and The length and time of recovery
Animals: Graze more of the whole landscape Select a wider variety of plant species
Planned multi-paddock grazing
Ranch road
Landscape impact of continuous grazing
Existing fenceElectric fence
Water point
Restoration using multi-paddock grazing
Degraded tallgrass prairie18 paddocks + water pointManaged to improve plant species
Noble Foundation, Coffey Ranch
Restoration using multi-paddock grazingNoble Foundation, Coffey RanchCharles Griffith, Hugh Aljoe, Russell Stevens
Summary of Managing for Desired Outcomes
Match animal numbers to available forage
Spread grazing over whole ranch
Defoliate moderately in growing season
Short grazing periods
Adequate recovery before regrazing
Graze again before forage too mature
Adaptively change these elements according to changing conditions
Teague et al. 2013
Managing proactively for best results
% Leaf Volume Removed
10%
20%
30%
40%
50%
60%
70%
80%
90%
% Root Growth Stoppage
0%
0%
0%
0%
2-4%
50%
78%
100%
100%
Range ConditionExcellent Good Poor
0
10
20
30
40
50
60
70
80
0 5 10 15 20 25
days of grazing in cycle
kg
gain
/he
ad
fo
r s
eas
on Low SR
High SR
Barnes and Denny cited by Norton 2003
Days of grazing before recovery
Managing high animal performance
0
10
20
30
40
50
60
70
80
0 50 100 150
days of rest in cycle
kg
gain
/he
ad
fo
r s
eas
on
Barnes and Denny cited by Norton 2003
Days of recovery in cycle
Managing high animal performance
What we need to know:
What are the mechanisms causing degradation?
What management reverses degradation?
How good is Planned Holistic Management as a restoration and management tool?
Where does it work and not work?
How does it need to be managed to make it work as well as it can?
Understanding causal mechanisms is critical to knowing how to manage to regenerate from a degraded situation.
Equilibrium of soil formation
and soil erosion
Decreased cover, productivity and SOC
Deteriorated soil structure
Decreased infiltration and water
holding capacity
Degradation Spiral
Decreased cover and SOC
We know what causes this at
the small scale
Increased cover and SOC
Regeneration Spiral
Increased cover, productivity and SOC
Enhanced soil structure
Enhanced infiltration and water holding
capacity
How to manage for this at the ranch scale?
Thurow 1991; Teague et al., 2011
Managed with Holistic Planned Grazing
No stock for decades
Semi-arid Karroo region in South AfricaAverage rainfall = 14”
H2O, CO2H2O, CO2
Planned multi-paddock grazing, when adaptively managed to give best vegetation and animal performance, has the potential to produce superior long-term:
1. Conservation and restoration of resources;
2. Ecosystem goods and services; and
3. Ranch profitability
We tested the hypothesis that at the commercial ranch scale:
An Alternate Ranch Scale Hypothesis
Influence of multi-paddock grazing on soil and vegetation
In each county on 3 neighbouring ranches :Continuous graze @ ± 20 ac/AU (Best in class continuous)Continuous graze @ ± 10 ac/AU (Most common management)Planned multi-paddock @ ± 10 ac/AU (Best in class)
Grazing treatment at least 10 years
0
5
10
15
20
25
30
35
40
Heavy Continuous Heavy Rotation Light Continuous
Bare
gro
und (%)
Bare Ground
a
bb
P = 0.0006
HeavyMulti-camp
Teague et al. 2011
ParameterGrazing Management
Heavy continuous
Light continuous
Multi-paddock
Grazing exclosure
Total bacteria (g m-2) 82a 74a 78a 98a
Total fungi (g m-2) 97b 98b 174a 105ab
Fungi to Bacteria ratio 1.2b 1.1b 3.1a 0.7b
Soil Microbes
Importance of Fungi
Fungi provide: Access and transport nutrients
Extend root volume and depth
Exude glomalin to enhance soil C
Increase water and nutrient retention
Increase drought resistance
Plant growth highest with highest fungal – bacterial ratio
Killham 1994; Leake et al. 2004; Averill et al. 2014
Penetration Resistance (compaction)
0
50
100
150
200
250
300
Heavy Continuous Heavy Rotation Light Continuous
Energ
y (Joules)
a
c
b
P = 0.0005
HeavyMulti-camp
Total Carbon Stock in Top 90 cm (t/ha)
Heavy continuous
Light continuous
Multi-paddock
Russ Conser SHELL pers comm
160
140
120
100
80
60
Soil Carbon, Nutrients and Water
Parameter Heavy Continuous
Light Continuous
Multi-paddock
Soil Organic Matter 3.1b 4.4b 4.86a
Cation Exchange Capacity 24.6b 23.7b 27.4a
Water holding (Gal/acre) 55,700 79,059 87,324
Tall Grasses
0
500
1000
1500
2000
2500
3000
Heavy
Continuous
Heavy Rotation Light Continuous
Biomas
s (k
g ha-
1)
b
a
b
P = 0.003
HeavyMulti-camp
Mid Grasses
0
500
1000
1500
2000
2500
Heavy
Continuous
Heavy Rotation Light Continuous
Biomass
(kg h
a-1)
b
ab
aP = 0.188
HeavyMulti-camp
Annual Forbs
0
100
200
300
400
500
600
Heavy Continuous Heavy Rotation Light Continuous
Biomass
(kg h
a-1)
a
b b
P = 0.014
HeavyMulti-camp
Profit Scenarios for HC or LC farms (20-year scenario) under a CO2 price of $6 per ton
Initial Farm
management
Practice Change Economic
Profit
($ ha-1)
Carbon
Profit
($ ha-1)
Total
Profit
($ ha-1)
Best
Choice
Initially
Practicing HC
HC unchanged -2.39 0 -2.39
HC → MP 16.29 32.97 49.26
HC → LC -0.31 28.77 28.46
Initially
Practicing LC
LC unchanged -0.31 0 -0.31
LC → MP 16.29 0.09 16.38
LC → HC -2.39 -28.77 -31.16
Both ecological condition and profitability increase with increasing number of paddocks
Adjusting HPG management with changing conditions increases ecological condition and profitability
Short periods of grazing with adequate recovery gave the greatest profit and improved ecological condition
Profitability is decreased if recovery is too long
HPG management ameliorated impact of increasing stocking rate in proportion to number of paddocks
Journal of Environmental Management 2014
Simulation modelling results
Successful multi-paddocks managers use: Flexible stocking to match forage availability
Spread grazing over whole ranch
Moderate grazing during growing season
Short graze periods
Allow recovery before regrazing
Graze again before forage too mature
Adaptively adjust to prevailing conditions
Use multiple species
Summary
Appropriate regenerative grazing management:
Sequesters more soil carbon
Improves watershed function
Improves species composition
Stabilizes soil and soil fertility
Enhances wildlife and biodiversity
Improves economic returns while improving the resource base
Conclusions
Improving Pasture Soil Health
Improve soil microbe function by:• Perennial plants rather than annuals
• Manage for most productive plants
• Leave adequate plant residue
• Use diverse species mixes and cover crops
• Eliminate tillage
• Minimize bare ground
• Use organic soil amendments
• Reduce N-fertilizer use
• Grow plants for maximum months each year
Delgado et al 2011; Rodale 2014; Jones, 2014
Soil health differences due to management
Christine Jones, 2014 Multi species pasture
High density grazing
Using regenerative cropping and grazing management can:
Build SOC levels and soil microbial functions
Control erosion more effectively
Build soil fertility
Reduce damaging inputs
Enhance watershed hydrological function
Increase biodiversity
Could result in agricultural soils being a net GHG sink rather than a major GHG source
Importance for Ecosystem Function?
Northern Great Plains carbon sinks and emissions of:
Light continuous grazing -0.783 tons CO2eq /ha/yr
With enteric methane of 0.176 tons CO2eq /ha/yr
Heavy continuous grazing -0.618 tons CO2eq /ha/yr
With enteric methane of 0.484 tons CO2eq /ha/yr
Liebig et al., 2010
Data from pasture and southern tallgrass prairie
Best pasture management sequestered 11 tons CO2eq /ha/yr
Best multi-paddock grazing on prairie sequestered 11 tonsCO2eq /ha/yr more than heavy continuous grazing
Teague et al., 2011
Conant et al., 2001
Importance for climate change mitigation
-3.0 t C ha-1 yr-1 for 263 mil ha
Soil Health for Climate Change Mitigation?
Conant et al., 2001; Teague et al., 2011
25% Regenerative cropping and
grazing
Current Reduce Ruminants
Soil Health for Climate Change Mitigation?
-3.0 t C ha-1 yr-1 for 263 mil ha
Conant et al., 2001; Teague et al., 2011
25% Regenerative cropping and
grazing
50% Regenerative cropping and
grazing
100% Regenerative cropping and
grazing
Current Reduce Ruminants
Using regenerative cropping and grazing management to:
Build SOC levels and soil microbial functions
Control erosion more effectively
Could result in soils being a net sink for agricultural GHGs rather than a major source of GHGs as at present.
Importance for Climate Change Mitigation?
Future Management Research……………….(1)
Research needs to investigate:
How good is Holistic Planned Grazing as a restoration and management tool?
What multi-paddock management best reverses the causes of degradation?
Where does it work and not work?
How does it need to be managed to make it work as well as it can?
Include ranch-based research at scale of management
Use retrospective, remote sensing to evaluate 20-year impacts of different management at landscape scale
Develop and test theories to check conclusions for inconsistencies with evidence from other sources
Corroborate output of biological models with field results from commercial ranches under a range of management strategies
Use models to determine what combination of management choices yields superior results?
Future Management Research……………………..(2)