Application Methods for Liquid Manure On Perennial Forages: North American Experience.

Liquid manure has the potential to supply much needed nutrients, especially N, for perennial forages. However, the value of this practice is limited because typical broadcast application results in large losses of NH₃-N, and can create other problems such as odor, contamination and damage of forage, nutrient imbalances, and runoff losses of nutrients and pathogens. Previous research, much of it in Europe, has shown that NH₃ losses can be reduced and crop N utilization improved by alternative application techniques such as shallow injection or trailing-foot application. Recent research in Canada and the US with liquid dairy and swine manure has shown increased N utilization and grass forage yields and NH₃-N volatilization reductions of 30 to over 50% from surface banding of liquid manure with a trailing-foot technique compared to broadcast application. Application with shallow (<5-cm) or deeper (10-cm) injection were the most effective in reducing odor and ammonia emission but have the potential to damage the sward. A novel technique that applies surface-bands of slurry over aeration slots provided greater NH₃-N loss reduction than surface banding alone, while increasing N utilization and decreasing odor and N and P runoff losses. These improved techniques provide agronomic and/or environmental benefits compared to broadcast surface application on perennial forages.