Reduction of ammonia emission by slurry application techniques

Livestock manures and slurries are, currently, almost entirely surface appl ied to land in the UK but research has shown that, under experimental condi tions, injection of slurry or restricted surface placement, can considerabl y reduce ammonia (NH3) emissions following land spreading. In experiments r eported in this paper, treatments were based around a slurry plot applicato r, incorporating surface broadcast, band-spread, trailing shoe and shallow injection (open slot) application techniques. In a total of 16 experiments over the period July 1995-June 1997, NH3 losses following application were significantly reduced (probability P < 0.05) on five occasions by at least one of the modified application techniques and averaged, 40, 25, 23 and 17% of the ammonium-N (NH4-N) applied, respectively, for splash-plate, band sp read, trailing shoe and shallow injection techniques. The overall reduction in NH3 emissions provided by the band-spread, trailing shoe and shallow in jection techniques, was 39, 43 and 57% relative to conventional surface bro adcast application. Whilst application technique consistently affected NH3 emissions, there was generally little observable effect on crop yield or ni trogen offtake in assessments undertaken within this project. It is apparen t that soil moisture content, soil temperature, slurry dry matter content a nd crop growth are all factors with potential to affect the results obtaine d. Greater understanding of the interaction of application technique with t hese factors is required. (C) 2000 Silsoe Research Institute.