The incorrect use of effluents from cattle farming can lead to potential pollution of the environment. The aim of this work was to study the effects of pre-treatment of slurry by acidification and/or the method of slurry application on soil on the nitrogen dynamics, namely gaseous emissions of ammonia (NH3) and nitrous oxide (N2O) as well as nitrate leaching. A field trial with oat (Avena strigosa) has been carried out in two types of soil, with a sandy structure and the other one with a sandy-loam structure. The treatments applied were control (without slurry application), raw slurry applied by injection, raw slurry applied to soil surface followed by incorporation and acidified slurry applied to soil surface followed or not by incorporation. For each treatment, three replicates have been carried. Gaseous emissions of NH3 and N2O have been measured, as well as leachate sampling whenever precipitation occurred. Leachate samples were analyzed for nitrate concentration, pH and EC. From the results obtained and according to the treatments, it was found that to reduce nitrogen losses by ammonia volatilization and nitrate leaching, the use of acidified slurry followed by soil incorporation is the best option for both soils without causing any decrease in oat production.

Mestrado em Engenharia do Ambiente - Instituto Superior de Agronomia