Emergency mass disposal of milk: Options and considerations

Abstract

The disposal of excess milk can pose significant challenges for dairy farms during supply chain disruptions, extreme weather events, or plant closures. Improper disposal methods risk causing environmental damage, public health issues, and regulatory violations. This study evaluates three on-farm milk disposal methods, lagoon discharge, composting, and land application, to guide the effective management of large-scale milk disposal events. Laboratory experiments assessed the impact of milk disposal on lagoon water quality, highlighting that lagoon discharge was feasible for large-scale operations but increased total solids and chemical oxygen demand (COD), potentially overloading the system's treatment capacity. Similarly, experiments on composting showed that adding milk enhanced compost quality but required careful monitoring to prevent moisture imbalance and odors. For land application, experiments demonstrated improvements in soil health and plant growth but also revealed risks of nutrient imbalance and gas emissions, particularly at higher application rates. Dividing milk into smaller, multiple applications consistently reduced adverse impacts across all methods. Each method's suitability depends on farm size, infrastructure, and disposal volume. Lagoon discharge is better suited for large farms with sufficient capacity to manage treatment risks. Composting works well for smaller volumes, while land application benefits soil health when carefully managed. The findings have practical applications in helping dairy farms select appropriate disposal strategies, minimizing environmental harm, and complying with regulations during large-scale milk disposal events. Additionally, this study serves as a foundation for creating more comprehensive guidelines and strategies to address milk disposal challenges, fostering sustainable practices across diverse agricultural settings.