The Converting Our Waste Sustainably Act of 2026 modifies the Environmental Quality Incentives Program under the Food Security Act to provide government payments to farmers and ranchers who adopt alternative manure management practices that reduce greenhouse gas emissions and improve environmental conditions. These practices include rotational grazing, compost-bedded barns, manure separation systems, and on-farm composting that generate environmental benefits like reduced methane emissions, improved water quality, and increased carbon storage. The bill prioritizes payments for small and medium-sized dairy and livestock operations, beginning farmers, and disadvantaged farmers, and allows up to 100 percent cost reimbursement with advance payments covering at least 50 percent of costs related to equipment and technical assistance through three-year contracts. The Secretary of Agriculture must develop criteria for evaluating applications, establish procedures for group composting projects, publish emissions reduction factors, and develop new composting standards within one year of the bill's enactment.