(374ay) Carbon Footprint Study of Grain and Forage Crops for Dairy Milk Production in the United States

Authors: 
Adom, Sr., F. K., Michigan Technological University
Workman, C., Michigan Technological University
Maes, A., Michigan Technological University
Bergmann, Z., Michigan Technological University
Clayton-Nierderman, Z., University of Arkansas
Thoma, G., University of Arkansas
Shonnard, D. R., Michigan Technological University


A carbon footprint study of cultivation and harvesting of grain and forage crops used for production of dairy milk in the U.S was conducted, and a preliminary impact assessment of a single dairy feed mill in Michigan was also undertaken. The final analysis yields a greenhouse gas (GHG) impact assessment of dairy feed production and processing in the U.S. on a regional basis. This study is a subsystem of larger study undertaken for the dairy industry sector to identify leverage points where innovation can lead to significant reductions in the carbon footprint of dairy products. Commonly used dairy feedstuffs in the U.S. were identified based on a recent literature review and information from dairy farm surveys. These dairy feed ingredients include but are not limited to the following; soybean, soybean meal, oats, wheat, forage, dry distillery grain, corn grain/silage, and many others. By dividing the U.S into five (5) dairy regions the following input data for the cultivation of dairy feedstuff were collected for each region; crop production data and budgets, fuel and electricity, fertilizers and soil amendments (N, P, K, Sulfur, Boron & Lime), and crop protection chemicals. Life Cycle Inventory (LCI) data for these inputs were mainly collected from farm extension and the National Agricultural Statistical Service (NASS) on a regional basis. In addition to consulting other relevant LCA studies and published articles and reports, this cradle-to-farm gate GHG impact analysis was conducted utilizing the Ecoinvent unit processes in SimaPro version 7.1. In the final analysis, the GHG intensity (kg CO2 eq. /kg dairy feed ingredient) for each dairy feedstuff was calculated for the five (5) U.S. dairy regions.In developing a preliminary cradle-to-dairy farm gate feed mill analysis, crop input data mentioned above were considered as well as other inputs like; vitamins, minerals, supplements, electricity and natural gas . A survey was created and applied to collect data from a single mill operation in Michigan. The feed mill analysis accounted for GHG impacts for the following; transportation of feed mill inputs to milling site, feed mill inputs, energy usage (natural gas, electricity) on milling site and transportation of milled products to dairy farms. A combination of Ecoinvent unit processes in SimaPro 7.1 (for feed mill ingredients comprising a majority of feed mass, other than the crops already mentioned above), Economic Input-Output Life Cycle Assessment (EIOLCA) and Open-Input/Output (Open IO) approaches (for a large number of ingredients whose mass contribution to dairy feed was relatively small) were used to estimate GHG burdens. In the case of the numerous mill inputs (supplements, minerals, vitamins, etc.), purchase cost data provided in the farm survey response were used accordingly by matching relevant economy sectors in the EIOLCA tool. The final carbon footprint analysis estimates GHG emitted from feed mill operations on the basis of one kilogram of dairy feed output from the mill.