Meat Eaters Guide: Methodology - Environmental Working Group

Soybean meal Production Input Details
CleanMetrics’ calculation of .59 kg CO 2 e per kg of soybean meal is based on the following assumptions:
• A typical soybean meal production uses electricity, diesel, and natural gas and converts about
1.21 kg of soybean to 1 kg of meal and extracts 0.191 kg of pure oil (leaving some oil in the
meal) 73 .
• Inputs and resources are allocated (using mass-based economic allocation) in the ratio of
37.7:15.8 to the meal and oil.
• About 2 percent of the input mass is disposed as waste.
c. Alfalfa Production
CleanMetrics’ calculation of .13kg CO 2 e per kg of alfalfa is based on average alfalfa production input
data from California’s Siskiyou County. 74 The crop is assumed to yield 6.0 tons of hay per acre with
more than three cuttings per year.
Production input details per acre:
• 2.5 acre feet of water through wheel-line and center pivot sprinklers (slightly less than California
average of four acre feet of water/acre)
• 75 lbs. of sulfur; 100 lbs. of phosphorus75 • 49 ounces of pesticide
• 4 gallons of gas and 6.7 gallons of diesel
In this model of alfalfa production, production of inputs constitutes 43 percent of emissions, followed
by on-farm soil emissions (34 percent) and on-farm energy use (25 percent). Transport of inputs is
negligible. Compared to soybean production, CleanMetrics applied a similar but smaller adjustment
of 0.2 N2O-N/acre/year for the GHG soil emission estimates for alfalfa, based on field studies and a
literature review regarding emissions from late growth stages of legumes76 .
Figure 11. Emissions Sources of Alfalfa Production
Environmental Working Group Meat Eaters Guide: Methodology 2011 43