Methylenediurea is primarily used as a slow-release nitrogen fertilizer in agriculture. It provides a controlled release of nitrogen, which helps in reducing nitrogen loss through leaching and volatilization. This makes it particularly effective for crops that require a steady supply of nitrogen over an extended period, such as turfgrass, ornamental plants, and certain field crops. The slow-release property also minimizes the risk of over-fertilization, promoting healthier plant growth and reducing environmental impact. Additionally, it is often utilized in combination with other fertilizers to optimize nutrient availability and improve soil fertility over time.