Slurry acidification outperformed injection as an ammonia emission-reducing technique in boreal grass cultivation
Riikka Keskinen, Maarit Termonen, Tapio Salo, Sari Luostarinen, Mari Räty
Abstract
Abstract Ammonia (NH 3 ) constitutes the single largest loss of manure nitrogen (N), making measures targeted at reducing its emissions meaningful for the environment and the overall efficiency of manure N use. In this study, the performance of two emission-reducing techniques, acidification and injection, were studied in a field experiment with grass ley over two growing seasons. Emissions of NH 3 , crop growth, and N use efficiency were determined from plots fertilized with cattle slurry either band spread, injected or band spread after acidification. The approximate cumulative NH 3 losses from the plots with band-spread untreated slurry amounted to about 22 kg NH 3 -N ha −1 over the observation periods in 2017 and 10 kg NH 3 -N ha −1 in 2018. The injection and acidification reduced the estimated cumulative NH 3 emissions by 43 and 95% respectively in 2018, and both by 97% in 2017. In 2017, the emission-reducing techniques had no impacts on crop growth, but in 2018, acidification increased dry matter yield by 29% and apparent N recovery by 65% compared with band-spread untreated slurry. According to the current results, acidification consistently produced the lowest NH 3 emissions and a discernible positive yield effect. It can therefore be recommended instead of injection for reducing NH 3 emissions in boreal grass cultivation.