LCA Food 2012 in Saint Malo, France! - Manifestations et colloques ...

PARALLEL SESSION 7B: BEEF PRODUCTION SYSTEMS 8 th Int. Conference on LCA in the
Agri-Food Sector, 1-4 Oct 2012
An assessment of greenhouse gas emissions and economics of grass
based suckler beef production systems
Anne-Marie Clarke 1 , Paul Crosson 1,* , Padraig Brennan 2
1 Animal & Grassland Research and Innovation Centre, Teagasc, Grange, Dunsany, Co. Meath, Ireland
2 Bord Bia, Clanwilliam Court, Lower Mount Street, Dublin 2, Ireland
Corresponding author. E-mail: paul.crosson@teagasc.ie
ABSTRACT
The objective of this paper was to evaluate the impact of stocking rate (kg of organic nitrogen (N) per hectare (ha)) for steer beef
production system on technical and economic performance and greenhouse gas emissions. Carcass output and profitability increased
with increasing stocking rate. At a stocking rate of 150 kg organic N/ha, total emissions were lowest per kg of beef carcass (23.4 kg
CO2e /kg beef) and per hectare (9.7 t/CO2e/ha). The highest output and economic returns were achieved at the highest stocking rate
(220 kg organic N/ha). Enteric fermentation was the greatest source of GHG emissions and ranged from 46% to 44% of total emissions
with increasing stocking rate. Net margin per tonne of CO2 e (emission efficiency) increased with increasing stocking rate.
Keywords: LCA, profitability, stocking rate
1. Introduction
In Ireland, agriculture is the largest contributor of greenhouse gas (GHG) emissions accounting for 30.4%
of national emissions in 2010 (EPA, 2011a). Agriculture will be required to share the burden of emissions
reductions based on the EU target to reduce emissions by 20% by 2020. The primary GHGs from agricultural
production are methane (CH4) and nitrous oxide (N2O). Of emissions from agriculture, enteric fermentation,
manure management and nitrogen additions to agricultural soils account for 47%, 28% and 20% of
total emissions, respectively (EPA, 2011b). Life cycle assessment (LCA) is a method that evaluates the environmental
impact of products and is regulated by the International Organisation for Standardisation (ISO)
standards (ISO, 2006). One of these environmental impact categories is Global Warming Potential which is a
relative measure of how much heat a greenhouse gas traps in the atmosphere. The result of an LCA study is
reported in terms of relative impact per unit product, known as the functional unit (ISO, 2006).
A number of LCA studies (Nguyen et al., 2010; Peters et al., 2010; Roy et al., 2012) have been carried
out on beef cattle production and in most cases the GHG emissions are reported per unit (kilogram) of meat
produced in carbon dioxide equivalent, (CO2e). Roy et al., (2012) reported that GHG emissions of beef (35.6
kg CO2e/kg-meat) were greater than that of pork (6.9 kg CO2e/kg-meat) or chicken (6.0 kg CO2e/kg-meat) in
Japan. Peters et al., (2010) examined red meat production in Australia and the results of this study showed
that farm level emissions were responsible for the largest proportion of the total burden compared to feedlot
and processing stages of its lifecycle. Nguyen et al., (2010) reported that suckler cow calf-beef production
system produced 27.3 kg CO2e/kg-meat (slaughter weight), while dairy calf to beef systems produced on
average 17.9 CO2e/kg-meat. Casey and Holden, (2006), White et al., (2010) and Foley et al., (2011) examined
the effect on greenhouse gas emissions of different farm systems. However the effect of increasing
stocking rate on greenhouse gas emissions for Irish suckler beef systems has not been investigated.
The objective of this paper was to evaluate the impact of stocking rate (kg of organic nitrogen (N) per
hectare (ha)) on steer beef production systems for technical and economic performance and greenhouse gas
emissions.
2. Methods
A bioeconomic model of suckler beef production systems, the Grange Beef Systems Model GBSM
(Crosson et al., 2006; Crosson, 2008) was used to generate steer beef cattle system scenarios and to quantify
the technical and economic performance of these systems. The scenarios were based on spring calving suckler
calf to beef research farm systems in Ireland finishing steers at 24 months of age and heifers at 20 months
of age. (Drennan and McGee, 2009). The GBSM runs on a monthly time-step and assumes a steady state
system over a calendar year. The output data of the GBSM specifies the essential input data for the LCA
model that estimates the greenhouse gas emissions associated with grass based suckler beef production systems.
This includes animal type and numbers, animal weights, feed intake, feed characteristics (eg DM,
DMD, nitrogen concentrations, gross energy), manure application profile, nitrogen fertiliser application
(kg/ha), beef produced (kg), lime application (kg/ha) and electricity consumption (kw). This model also provides
financial performance data such as farm net margin. Net margin includes direct and overhead costs and
611