A Short-term Study to Compare Field Strategies for Ammonia Emission Mitigation

Abatement of ammonia (NH3) emissions is crucial in calcareous soils under semiarid Mediterranean climates. The aim of the study was to compare NH3 emissions using different slurry application methods. An experiment was carried out on a clay loam soil to evaluate NH3 emissions before sowing (S-) and at winter cereal tillering (T-). Pig slurry was applied using two methods, one which applied slurry by splashing it over a plate (SP) and the other applied slurry in strips using trail hoses (TH). Emissions were measured using semi-static chambers at variable intervals for 12-13 d (315.5 h for S- and 287 h for T-). Maximum NH3 flux emissions were always observed during the earliest period of measurements after slurry spreading (3.5-5 h). Before sowing, regardless of the method, accumulated NH3 losses (during 315.5 h) ranged between 2-3 kg NH3-N ha-1 because of the low dry matter (DM) of the slurry content (<2%) which enhanced infiltration. Losses represented about 2-3% of the total N applied. At cereal tillering, average accumulated losses of NH3 (during 287 h) were 1.7 kg N ha-1 using TH (1.1% of total N applied), and were as high as 5.4 kg N ha-1 (3.2% of total N applied) using SP. Because N top-dressing is recommended as a measure to increase its efficiency, TH is recommended vs. SP. Thus, this short-term study concludes that TH may reduce NH3 emissions in semi-arid environments. Further study of these strategies is recommended under different climate and soil conditions.