Livestock Slurry and Sustainable Pasture Management: Microbial Roles, Environmental Impacts, and Regulatory Perspectives in Ireland and Europe

Pastures serve as the primary source of grass and forage plants for grazing livestock, requiring adequate nutrient input to sustain growth and soil fertility. Slurry from the livestock industry is widely utilized as a sustainable and cost-effective alternative to chemical fertilizers. Microorganisms within the slurry–pasture system are essential for breaking down organic matter, facilitating nutrient cycling, and improving soil health. However, mismanagement or inefficient microbial decomposition can lead to significant issues, such as nutrient leaching into water bodies, causing eutrophication, antimicrobial resistance, and reduced nutrient availability in pastures, which, in turn, may negatively impact livestock productivity. Thus, this paper investigates the composition and benefits of livestock slurry in pasture management, highlights microbial roles in nutrient cycling, and evaluates regulatory frameworks in Ireland and Europe. Additionally, it examines the environmental risks associated with improper slurry application, providing insights to support sustainable management practices.