Agricultural intensification has resulted in a ten-fold increase in crop yield over the past hundred years, but these advances have not occurred without costs: soils have eroded and soil quality has decreased, incurring a soil carbon debt equivalent to 65 ppm of atmospheric CO2. Increased fertilizer use causes the majority of the emissions of the greenhouse gas N2O, and drought stress increasingly threatens yields. Given the scale of domestic (and global) agriculture resources, there is great potential to reverse these trends by focusing plant breeding toward new cultivars with enhanced root systems to improve soil quality and improve biogeochemical cycling. Development of new root-focused cultivars could dramatically and economically reduce atmospheric CO2 concentrations without decreasing agricultural yields.
To this end, the ARPA-E program, Rhizosphere Observations Optimizing Terrestrial Sequestration (ROOTS), is pursuing technologies that increase the precision and throughput of crop breeding for improved root-soil biogeochemical function. ROOTS seeks to develop novel, non-destructive, field deployable technologies to:(1) measure root functional properties; (2) measure soil functional properties; and (3) advance predictive and extensible models that accelerate cultivar selection and development. These technologies—especially integrated systems—could greatly increase the speed and efficacy of discovery, field translation, and deployment of improved crops and production systems that significantly improve soil carbon accumulation and storage, decrease N2O emissions, and improve water efficiency. The aspiration of the ROOTS program is to develop crops that enable a 50% increase in carbon deposition depth and accumulation, a 50% decrease in fertilizer N2O emissions, and a 25% increase in water productivity. Taken over the 160 million hectares of actively managed U.S. cropland, such advances could mitigate ~10% of total U.S. greenhouse gas emissions (GHG) annually over a multi-decade period, while also improving the climate resiliency of U.S. agricultural production.