Monitoring ammonia (NH3) emission is time consuming and requires specialized measurement equipment. The measurement time can be reduced if there is a close relationship between time and subsequent cumulated NH3 emission values. A statistical analysis was employed to study the relationship between cumulative NH3 emissions over varying time intervals and final NH3 loss after 3 days of measurement. A large number of multi-lot field experiments on NH3 loss after the application of animal and biogas slurries by trail hoses to crops in Northern Germany were carried out from 2007 to 2010. Based on data from 2007, measured using a passive sampler method, a linear empirical model was developed to calculate final cumulated NH3 loss from intermediate cumulated losses. Linear model fitting showed that cumulative NH3 losses after 24 h were significantly correlated with final cumulated NH3 losses, explaining more than 0.98 of its variation. The linear coefficient was 1.34, implying that c. 0.73 of final NH3 loss occurred within the first 24 h. Validation by datasets obtained from another year (2008), two additional measurement methods and another agro-region (marsh area, 2009/10) resulted in a close agreement of model predictions with measured data within the range of model uncertainty and data variation. The results underpin the feasibility of calculating final NH3 losses from cumulative losses during first 24 h after slurry application and can be used to simplify NH3 loss measurement after the application of liquid slurries in multi-lot field experiments. The slope of the linear relationship is only valid for liquid slurries and the environmental conditions of the present study, which are typical for many agro-regions in north-western Europe, and will have to be adapted for different climatic conditions. A time-efficient measurement of emissions from solid organic fertilizers might require a different time span.