A Life Cycle Assessment of Guar Agriculture

Abstract Guar gum, the main product of the guar crop, is used widely in the US as an emulsifier in the food industry and as fracturing fluid additive in the oil and gas industry. The US is the number one global importer of guar, and interest has grown to domestically cultivate guar in the US. Guar is an annual desert legume native to India and Pakistan. The goal of this study was to evaluate the environmental sustainability of growing guar in the U.S. via a life cycle analysis (LCA). The LCA helps identify the information gap for US agriculture and guide future field studies to optimize guar cultivation in the US. This study concluded that in terms of environmental sustainability, irrigation, harvesting, and P-fertilization methods offer the most opportunity for improved guar agricultural sustainability. This is promising because one of guar’s prominent characteristics is its high water use efficiency and ability to grow in marginal soils. Lowering irrigation and water use can be implemented with simple management practice changes like optimizing irrigation. In addition, this study shows that there is an opportunity for field trials to optimize fertilizer application rates to achieve the greatest yields. This study also found a knowledge gap with respect to C soil fluxes and field emissions of N and P from guar agriculture. As the United States pursues adopting guar agriculture in the Southwest, it will be critical to evaluate irrigation to achieve maximum yields (e.g. drip, flood, sprinkler) and fill fertilizer and emissions knowledge gaps.