Science-based approaches to soil health

View of rangeland surrounding Sawtooth MountainsManagement practices that promote soil health in croplands can deliver multiple benefits for nature and people, including cleaner air and water and greater crop yield stability. In the United States alone, one or more of these practices – which include cover cropping, reduced tillage, nutrient management, and more – could potentially be implemented on nearly 400 million cropland acres. Yet, rangelands in the US occupy nearly twice the area that croplands do, and some rangelands have also experienced soil degradation issues, such as erosion. Could improving the health of our rangeland soils deliver similar benefits as on croplands and, if so, which practices on which types of sites hold the greatest potential? Answering this exciting question requires a rangeland-specific approach, because these lands differ from croplands in a number of important ways. For example, rangelands support higher numbers of rare species than do croplands, such that many rangeland managers seek practices that can safeguard these species at the same time as they improve soil health. Through the NatureNet Science Fellows program, the ASU Center for Biodiversity Outcomes is partnering with The Nature Conservancy to develop science-based approaches to rangeland soil health. Postdoctoral fellow Kelly Gravuer is working with mentors at ASU and TNC to investigate the potential of a relatively novel management practice: the surface application of organic amendments, such as compost, to rangeland systems. This practice has shown promise at a few sites in northern California, but at a broader scale, we don’t yet know what types of organic materials and rangeland application sites could provide the greatest benefits. Gravuer has been using meta-analyses of published studies and greenhouse experiments at ASU to address this question. Preliminary results from the meta-analysis indicate that certain combinations of site and amendment properties can yield greater benefits than others, and that the optimal implementation strategy may depend on which types of environmental and/or economic outcomes are the greatest priority. As a participant in the Managing Soil Organic Carbon working group supported by the Science for Nature and People Partnership, Gravuer is also collaborating with scientists based at TNC and Point Blue Conservation Science on a project to evaluate how a broader suite of rangeland management practices influence rangeland soil properties and conservation outcomes, using network-based approaches. Through these partnerships, the Center for Biodiversity Outcomes is supporting the identification of management practices that could improve rangeland soil health over millions of acres, while safeguarding the rich biodiversity that depends upon these lands.