The transition to sustainable agriculture will rely not only on developing sustainable management practices, but also on creating policies and market mechanisms to support their implementation. In the midwestern United States, developing markets for cover crops – including animal feed and bioenergy markets – could incentivize farmers to plant winter cover crops in corn-soybean rotations, which could have positive environmental benefits like increasing soil carbon sequestration and decreasing nitrogen leaching. However, complex interactions between management and environmental dynamics cause variable benefits across different locations. This variability must be considered when developing policies to promote cover crops and when considering the potential impacts of cover crop products, but it has not yet been thoroughly explored through a life cycle lens. We use modeled corn, soybean, and cover crop data and a life cycle assessment framework to answer: What is the potential per kg GHG and N leaching impacts of harvested winter rye? What variation can be expected in these impacts in the central Midwest? What are the main drivers of the impacts and of their variation?

Using the biogeochemical model ecosys and estimates of upstream impacts from GREET, we create spatially explicit life cycle inventories of key impacts of corn-soybean rotations under multiple scenarios, including business-as-usual (no cover crop), and a winter rye cover crop under multiple management practices, including varying planting dates, harvesting dates, fertilization rates, and harvest rates. Dynamic modeling of these scenarios allows for investigation of the relative roles of management practices, environmental characteristics, and upstream impacts in determining the total impacts of the cover crop. For example, preliminary results suggest fertilization of winter rye results in upstream GHG emissions that overshadow soil carbon benefits in most locations in high fertilization scenarios. Our results will also include the impacts of cover crop fertilization and harvest on soil carbon changes and nitrogen leaching and how much these impacts vary across weather and soil conditions. Combining life cycle inventory results across scenarios will produce a life cycle assessment that identifies the largest sources of impacts and also of uncertainty for a winter rye cover crop.

This analysis furthers discussion on the role of biogeochemical modeling in life cycle assessment and produces results that are important for those who wish to promote cover crop planting through marketing cover crop products and for those who wish to market cover crop products by promoting their environmental benefits.

Beef has a large environmental impact and is widely consumed in the United States. The United States federal government aims to find food protein production methods with GHG emissions 50% or less of current methods by 2028. One potential pathway to reduce the impact of the protein provided by beef is to instead consume meat alternatives. Heme proteins are a nascent additive to meat alternatives and are used to emulate gastronomic characteristics of beef. However the impact of heme alone as part of meat alternatives has not been explored in depth. Previous studies have compared the impact of a heme containing meat alternative with ground beef, but have not quantified the proportion of impact of heme. To study the environmental impact of heme protein production and its contribution to the impact of a meat alternative, two cradle-to-gate LCAs were conducted using information provided by Motif Foodworks. The LCA of meat alternative production compared its results with one kilogram of ground beef. The functional units used in this study were one kilogram of meat alternative and one kilogram of heme additive.

Heme protein had a carbon footprint of 117 kg CO2 eq. per kilogram of heme, while the meat alternative had an impact of 3.45 kg CO2 eq. per kilogram meat alternative, 90% lower than the global warming potential of the same quantity of ground beef. Furthermore, the meat alternative was 93% and 99% lower than ground beef in water consumption and land use respectively, yet had a 9% greater freshwater ecotoxicity impact. Impacts in each category were broken down and geospatial electricity mix and ingredient production analyses showed sensitivity to renewables content and growing locations. The key drivers of GHG emissions per functional unit of meat alternative production were identified using sensitivity analysis. Heme production rate resulted in the largest range of impact in global warming potential. Electricity, ingredient procurement and heme production parameters all have considerable impacts on product environmental performance and are potential areas to further improve the environmental sustainability of the meat alternative. This study demonstrates that despite the high impact of heme as a key ingredient in the meat alternative, the meat alternative has a lower environmental footprint than ground beef in most environmental impact categories, though technical parameters in its manufacturing can decrease relative performance. These results can be used to advance system sustainability through targeted improvements and inform the public of the environmental impact of meat alternative and plant-based protein production.

Global food systems are characterized by complex, dynamic, and predominantly linear supply chains. The need to transition towards a circular value proposition within the food supply chain (FSC) has led to different research efforts quantifying food loss and by-products from on-farm, post-harvest, and processing stages. These stages are estimated to account for 20-30% of total food loss and waste. They also generate a number of by-products (e.g. peels, seeds, pomace, etc.) that represent both a significant environmental burden and a largely untapped potential for valorization and profit generation. Despite recent efforts to characterize and map food loss and waste flows, there is still a lack of information and harmonization across the FSC to allow for a comprehensive quantification of food loss and by-products generated.

The processed tomato supply chain is one of the major FSCs in California, which supplies approximately one third of the world’s processed tomato products. This FSC epitomizes some of the challenges associated with implementing sustainability principles across the value chain. Despite the demonstrated potential of tomato processing by-products as a source of valuable molecules for high-value industries (e.g. pharmaceutics, cosmetics), the scalability has been limited. This limitation is partly due to the lack of quantification mentioned above, as well as the fact that the concentration and nature of the extractable chemical compounds depend on the variety, growing conditions, transportation, and processing conditions.

To fill this knowledge and data gap, we present a comprehensive model that quantifies the tomato by-products across California, identifies their associated chemical compounds, and links them to their commercial value. The model is based on a mass balance that considers the 24 counties with tomato industry operations in California, the tomato variety grown and intended for tomato processing within each county, the growing conditions (organic vs inorganic), and the processing conditions of each of the 17 processing facilities that manufacture tomato paste, peeled tomatoes, and/or tomato-based foods. The data were extracted from federal and national government agencies, seed suppliers, tomato processing companies’ websites, and scientific literature. The collected data were then cross-validated by expert opinion, harmonized, aggregated, and analyzed to quantify detailed material flows for the final mass balance.

Using California’s processing tomato industry as a case study, this research aims to explore the opportunity to extract high-value compounds by quantifying and characterizing what was previously considered low-value waste streams. The high granularity of our mass balance enables us to consider the influence of distinct processing conditions on the generation of food losses and by-products as well as determine the final chemical composition of a given stream. While the model was developed originally to analyze mass flows in the tomato industry, it can be adapted and applied to assess valorization opportunities for a range of food products and FSCs, both in California and across wider geographic.

Historical intensification of the food system has contributed to a number of environmental challenges, including air pollution, which is additionally damaging to human health. Exposure to ambient particulate matter less than 2.5µm in diameter (PM2.5) is an environmental health risk factor for chronic obstructive pulmonary disease (COPD), lung cancer, ischemic heart disease, stroke, among other causes of death. Of all of the anthropogenic air quality-related health damages in the United States (100,000 deaths), approximately one-fifth are from food and agricultural activities. In previous work, we showed that of the 17,900 annual air quality-related deaths from food and agricultural activities in the United States, 12,400 are from activities emitting ammonia, a precursor to secondary PM2.5. Manure management and synthetic fertilizer are responsible for nearly all of these ammonia-related deaths.

In this study, we focus on manure management activities contributing to PM2.5-related health damages in the United States for three livestock categories: poultry, cattle, and swine. We evaluate the direct air quality-related impact of the livestock production and benefits of implementing intervention strategies to reduce PM2.5-related health damages through ammonia abatement. We use updated primary PM2.5 and secondary PM2.5 precursor emissions inventories from the 2020 EPA National Emissions Inventory (NEI) with three reduced complexity air quality models (InMAP, EASIUR, AP3) to attribute health damages to specific commodities using updated activity data. Interventions to reduce PM2.5-related health damages include dietary shifts and changes to manure management practices (storage and application techniques) and proximity to dense populations.

Changes from the livestock related ammonia emissions inventory from the 2014 NEI to the 2020 NEI include updates in activity data resulting in higher reported ammonia emissions from livestock. Preliminary data suggests poultry, swine, and cattle livestock waste, not including land application, account for 8,700 out of 11,600 annual deaths from manure management in the updated model. Implementing ammonia emissions intervention strategies would reduce air quality-related health damages across the United States, especially in areas of intense agricultural activity.

Agricultural activity has been the main driver of nitrogen pollution in the Chesapeake Bay Watershed (CBW). Best management practices (BMPs) have been used to reduce nitrogen loading to the streams. Introducing perennial grasses and winter biomass crops into agricultural landscapes are two BMPs that can help with nutrient pollution while offering opportunities to produce renewable energy, through anaerobic digestion, and/or animal feed. In this study, we updated and used a nitrogen accounting model, the Commodity Specific Net Anthropogenic Nitrogen Inputs model (CSNANI), to represent the change in nitrogen inputs due to the introduction of grasses and winter biomass crops to act as BMPs, helping to reduce nitrogen loads to the streams, and providing new economic opportunities through producing biogas within the CBW. Besides that, we estimated the nitrogen demand necessary for common agricultural commodities in the region and biogas produced while adopting different BMP scenarios. CSNANI estimates the N flows associated with 20 crop commodities and 19 livestock commodities and internally relates crops required for livestock diets, thus enabling N inventory development for a study region through a nutrient flow analysis perspective. We developed scenarios to approximate land use changes corresponding to changes to the crops produced, we then used CSNANI to estimate changes in nitrogen flows in the CBW and the demand for nitrogen per commodity. In this analysis, cropland available for cultivation is not allowed to expand beyond current cropland use and grasses will be assumed to replace land currently used for corn-soybean production. In contrast, winter biomass crops were restricted to previously cultivated lands. Given that our scenarios reduce overall feed availability, we considered scenarios that held livestock production constant and those that reduced livestock production when grass displaced feed crops. This allows us to identify the implications in the regional nitrogen balance and consequences for the livestock sector for producing biogas from grasses and winter biomass crops as another source of animal feed. Our results show that there will be a reduction in the main components of the nitrogen input when implementing grasses in the landscape. The N input that comes from fertilizer can be reduced by a maximum of 8%, while N fixation can be reduced by a maximum of 14%. The reduction of N and the production of biogas come with the expense of producing feed in the region. Regarding nitrogen input to commodity production, our preliminary results indicate that for the baseline scenario, the animal commodities that consumed more kg N per kg of protein produced were beef meat (3.3), pork meat (2.0), and dairy milk (1.2); and the plant commodities that consumed more N per protein produced were oats (0.24), corn grain (0.23), and alfalfa (0.21). Ultimately, this assessment helps to evaluate the overall change in the nitrogen load to the region associated with the commodities’ production, the nutrient demand to produced agricultural commodities in the region, and draws attention to the benefits of introducing grasses and winter biomass crops as a strategy to improve the nutrient management of the CBW.