The Carbon Footprint of Sorghum


Executive Summary

In California and across the United States, consumers are demanding agricultural products with lower carbon footprints from their supermarket chains, animal feed manufacturers and ethanol producers. This demand has sparked a growing number of protocols and methodologies that attempt to measure, report and verify the carbon intensity of agricultural products around the globe with varying levels of success.

This report develops a gap analysis of existing carbon intensity methodologies for agricultural products, identifies a methodology for calculating the carbon footprint of sorghum using best practices from the methodologies reviewed (including methodologies used for certification in European and other markets) then conducts the largest ever comprehensive survey of over 300 sorghum farms in 9 states representing over 80 percent of the industry to calculate the carbon intensity for sorghum. This study was completed by SGS in collaboration with a third party, Strategic Marketing Research & Planning, for the recruitment of farmers and for the survey.

The goal of this study was to obtain real data on the carbon footprint of sorghum (as raw material) from cradle to farm gate to the next user in the supply chain (e.g., elevator, ethanol plant, etc.) and to be able to compare these data with other crops like corn. The sample size for this study was designed to be large enough to examine information across regions/districts in 9 states that account for 80 percent of planted sorghum acres. To determine carbon usage a sample of over 300 sorghum growers were surveyed that created a margin of error of +/-5.6 percent at a 95 percent level of confidence.

All GHG emissions (mostly CO2 and N2O) were included for sorghum with enough data gathered to represent the entire U.S sorghum industry. The system boundary for the study was sorghum farmers primarily producing sorghum for ethanol. Because sorghum tolerates dry climates it is mostly grown in the southwestern and central portions of the U.S. The values and representative sample therefore comes from mostly southwestern and central plains farmers. A four-year Olympic average yield was used.

The study found that the total carbon footprint for sorghum is 0.25 kg CO2e per kg of sorghum or 6.4 kg CO2e per bushel of sorghum. This value is calculated based on the average reported inputs per farm. The footprint value is an average value but ranges are wide. With a standard deviation of 0.1 kg CO2e per kg of sorghum for all farmers that filled out the total questionnaire and a range from 0.05 kg CO2e up to 0.74 kg CO2e per kg of sorghum, we can observe differing practices across the sample of farmers. The ranges mostly depend on differences in fertilizer application and the other energy inputs.

The findings in this report are the most comprehensive farm data collected to date for sorghum not dependent on third party estimates of sorghum use.

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