The effect obtained on lowering the emissions could be observed from storage up to application. Positive effects have been measured on the yields. The costs of acidification could be lower with the use of lower concentration acid and of lower degree of purity (as the production costs of acid of higher purity and concentration are more important). More investigations are needed to evaluate the effect of acidification on real scale production and also to measure emissions from arable land. The long time effect on soils of acidified manure has also to be evaluated.