The Advancing Research on Agricultural Soil Health Act of 2025 directs the Secretary of Agriculture to establish a standardized methodology for directly measuring soil carbon for research and conservation purposes within 270 days. This methodology will be developed through a review of existing practices and consultation with diverse stakeholders, including agricultural producers and soil carbon experts. It must be usable across various locations, measure to appropriate depths, and produce interoperable data for voluntary reporting by producers, supported by technical assistance and guidance in multiple formats. The bill expands existing agricultural research programs to prioritize soil carbon. It amends the Competitive, Special, and Facilities Research Grant Act to include research on measuring, monitoring, reporting, and verifying soil carbon sequestration and emissions. Furthermore, it modifies the Conservation Innovation Grants program to support soil health management systems focused on increasing soil carbon and developing cost-effective measurement tools, and requires on-farm demonstration projects for soil carbon sequestration under the Sustainable Agriculture Research and Education Program. A significant provision establishes a Soil Carbon Inventory and Analysis Network to inventory, monitor, and analyze soil carbon changes on eligible public and private lands across the United States. This network will conduct inventories every five years using the standardized methodology, documenting soil type, land use history, and environmental characteristics. Crucially, the program emphasizes individual protections, requiring landowner authorization, ensuring voluntariness, and safeguarding data privacy by preventing the inclusion of identifiable or personal information. Finally, the legislation mandates the development and maintenance of predictive modeling tools to estimate the impacts of various land management practices on atmospheric carbon, methane, nitrous oxide, and soil carbon sequestration. These user-friendly tools, developed in consultation with federal agencies and stakeholders, must be anchored in direct measurements and account for diverse factors like soil type and geography. The Secretary is required to annually report to Congress on the progress, accuracy, and updates of these modeling tools, with specific appropriations authorized for each key initiative.