understanding the impact of beef grazing on climate change
TRANSCRIPT
Understanding the Impact of Beef Grazing on Climate Change
Daniel L. DevlinDirector, Kansas Center for Agricultural
Resources and the Environment
Principal InvestigatorsDan Devlin
Kansas Center for Agricultural Resources and the Environment
Kansas State University785-532-0393
Jean SteinerGrazinglands Research Laboratory
USDA, ARS405-262-5291
NIFA CAP Project: Resilience and Vulnerability of Beef Cattle Production in the Southern Great Plains Under Changing Climate, Land Use and Markets
Amber Campbell2013C Throckmorton Ctr.Kansas State University
Project Manager
Project Funding
This project was supported by Agriculture and Food Research Initiative Competitive Grant no. 2012-02355 and 2013-69002-23146 from the USDA National Institute of Food and Agriculture.
Our Project is Concentrating on the Grazing Component of the Beef Industry
• Native, warm season tall grass prairie•Cool season pastures•Wheat pasture•Grazing of cover crops
What Are We Doing?• Measure and determine greenhouse gas contributions from
beef grazing systems• Develop management practices and grazing systems that
mitigate greenhouse gas releases • Develop adaptation strategies• Develop a lifecycle analysis of the beef industry from birth to
feedlot• Develop a user friendly model to assist beef producers
reduce greenhouse gas emissions while being economically feasible
What Are We Doing• Consumer education • Survey of farmer/rancher and extension agent attitudes and
needs concerning climate change• Climate data analysis and remote sensing of ET and
rangeland conditions• Grazing trials• Extension programs
GHG Emissions from Cattle• Carbon dioxide (CO2)– Normal metabolism / respiration– Fermentation of manure / burning
• Methane (CH4)– Fermentation within the digestive tract (mostly rumen)– Fermentation of manure & plant materials
• Nitrous oxide (N2O) (0-2% of manure N excreted)– From soils– Fertilizers
Pasture Scale Methane• Measured CH4 fluxes represent the balance between:
– CH4 emission from cattle and/or soil
– CH4 consumption by methanotrophic bacteria in soil
• Several factors govern production and consumption of CH4 in soil. Climate (temperature and light)Hydrology (soil water content, water flow, water table depth)Biogeochemistry (plant productivity, soil oxygen concentration,
and availability of electron acceptors like iron, sulfate, and nitrate)Soil properties (texture, porosity, bulk density)
Method Features Source
OPL/DA Integrates emissions from entire pasture Cows + calves + soil
GreenFeed Eructation from trained cows Cows only
IPCC Tier 2 Uses dry matter intake, forage energy content and methane conversion factor
Calf estimateCow estimate
Three Methods to Quantify CH4 Emissions
Intensive Field Campaign, National Grazinglands Research Laboratory, El Reno, OK
65 acre native tall grass prairie pasture
Challenges• Cattle density low (5300 m2/cow-calf)
• Grazing cattle are mobile point sources of CH4
• Increase in CH4 concentration above backgrounddownwind of herd is small
• 10 Lotek GPS3300R• WAAS enabled• 5 min fixes
Potential downwind concentrationsBackground concentrations
The GREENFEED SystemTo Measure Methane Emissions from Cattle
IPCC (2006) Tier 2 Calculation
GEI Gross energy intake (MJ animal-1 d-1)
Ym Methane conversion factor (% of GEI)
55.65 Energy content of methane (MJ kg-1 CH4)
𝑃𝐶𝐸𝑅=𝐺𝐸𝐼 ( 𝑌𝑚
100 )55.65
Method Per capita emission rate
g CH4 d-1 CCP-1
OPL/DA 359 ± 61
GreenFeed 385 ± 57
IPCC Tier 2 340 ± 57
Summary with Different Methods
• Methane emission converged on range 340-385 g d-1 CCP-1
• Uncertainty of measurements around 15-17%
• Calves contributed about 10% of total emissions
• Emission factor for beef cows with calves grazing early season tallgrass prairie pasture: 306 g CH4 d-1 AU-1
• This EF not applicable to cattle w/o calves
Conclusions
