Ammonia emissions from cattle dung, urine and urine with dicyandiamide in a temperate grassland

Deposition of urine and dung in pasture‐based livestock production systems is a major source of ammonia (NH3) volatilization, contributing to the eutrophication and acidification of water bodies and to indirect nitrous oxide emissions. The objectives of this study were to (i) measure NH3 volatilization from dung and urine in three seasons, (ii) test the effect of spiking urine with the nitrification inhibitor dicyandiamide (DCD) on NH3 volatilization and (iii) generate NH3 emission factors (EFs) for dung, urine and urine + DCD in temperate maritime grassland. Accordingly, simulated dung, urine and urine spiked with DCD (at 30 kg DCD/ha equivalent rate) patches were applied to temperate grassland. Treatments were applied three times in 2014 with one measurement of NH3 loss being completed in spring, summer and autumn. The NH3‐N EF was highest in spring, which was most likely due to the near absence of rainfall throughout the duration of loss measurement. The EFs across the experiments ranged between 2.8 and 5.3% (mean 3.9%) for dung, 8.7 and 14.9% (mean 11.2%) for urine and 9.5 and 19.5% (mean 12.9%) for urine + DCD, showing that ammonia loss from dung was significantly lower than from urine. Aggregating country‐specific emission data such as those from the current experiment with data from climatically similar regions (perhaps in a weighted manner which accounts for the relative abundance of certain environmental conditions) along with modelling is a potentially resource‐efficient approach for refining national ammonia inventories.