Nitrogen, essential for plant metabolism and soil health, is abundantly supplied by manures in agriculture. However, excessive manure application results in substantial nitrogen loss, leading to water pollution and greenhouse gas emissions. Biochar, a carbon-rich product of biomass pyrolysis, presents a viable solution to these challenges due to its stable carbon structure, high porosity, and extensive surface area. These properties enable biochar to enhance water retention, nutrient adsorption, and soil microbial activity, thereby reducing nitrogen leaching and volatilization. Incorporating biochar with manures in agricultural practices not only mitigates reliance on synthetic fertilizers but also improves soil fertility and water-holding capacity. Biochar’s ability to sequester carbon further contributes to reducing greenhouse gas emissions, making it a sustainable and eco-friendly amendment. This chapter reviews the mechanisms by which biochar influences nitrogen management, including its impact on nutrient dynamics, microbial activity, and greenhouse gas emissions. Additionally, it discusses the challenges of biochar production and integration with manures, emphasizing the need for optimized application strategies. By evaluating the role of biochar in enhancing nitrogen retention and availability, this chapter provides insights into effective nutrient management techniques. The chapter underscores the potential of biochar to address environmental concerns associated with manure management, offering a comprehensive strategy for sustainable agriculture and climate change mitigation.