LAUSR

Livestock excreta deposition on concrete farmyards has been identified as an important source of ammonia (NH3) emissions from agriculture. The objective of this study was to quantify the effect of urine application rate and four cleaning strategies on NH3 emissions from excreta deposited on a concrete yard. Three experiments were conducted on a concrete yard over a three week period in August 2016. Experiment 1 consisted of 1 kg dung applied with either (i) 0.67 l urine (1:0.67), (ii) 1 l urine (1:1) or (iii) 2 l urine (1:2). In experiments 2 and 3 the treatments were (i) non cleaned control, (ii) cleaned after 1 h and (iii) cleaned after 3 h. The cleaning method in experiment 2 and 3 was pressure washing and scraping, respectively. Ammonia emissions were measured using wind-tunnels for 72 h. Cumulative NH3 emissions increased linearly with increasing urine N rate and emission factors ranged from 46% to 67% of urine urea-N applied and from 22% to 29% of total N applied. In experiment 2 and 3 the greatest reduction in cumulative NH3 emissions was obtained from pressure washing at 1 h which reduced emissions compared to the non-cleaned control by 91%. Pressure washing at 3 h reduced emissions by 80% while scraping after 1 h and 3 h reduced emissions by 78% and 54%, respectively. Farmers should be encouraged to clean their animal handling yards as soon as possible after use in order to maximise reductions in NH3 emissions from this source.