Ammonia volatilisation from pig slurry and ANS with DMPP applied to Westerwold ryegrass (Lolium multiflorum Lam., cv. Trinova) under Mediterranean conditions

Ammonia volatilisation from agriculture represents an important nitrogen (N) loss which has both environmental and economic impacts. In regions where large amounts of manures are available, there is a need to find appropriate management strategies that help to reuse them without increasing ammonia volatilisation. A study was made of the effect on ammonia volatilisation and yield of fertilising ryegrass with pig slurry (PS) and ammonium nitrosulphate (ANS-26) alone and with the 3,4-dimethylpyrazol phosphate (DMPP) nitrification inhibitor added to them. The study was conducted under Mediterranean conditions at two different sites. The treatments (control, PS, PS + DMPP, ANS-26 and ENTEC®) were established in a randomised block design with three replicates. Ammonia was sampled daily after each fertilisation using semi-static volatilisation chambers. We hypothesised that PS could replace mineral fertiliser without substantially increasing ammonia volatilisation in the studied systems. Temperature positively correlated with ammonia emissions. On the whole, during the two years of the study, the PS treatments presented higher average cumulative ammonia volatilisation (25% of total ammonium nitrogen (TAN) applied at Site 1; 21% of TAN applied at Site 2) than the mineral ones (11% of TAN applied at Site 1; 10% of TAN applied at Site 2). At pre-sowing, ammonia volatilisation was significantly (p