Injeção de dejetos de suínos no solo em plantio direto associada a um inibidor de nitrificação: efeito nas emissões de óxido nitroso e amônia

Abstract

The application of pig slurry into the soil can result in losses of nitrogen (N) through volatilization of ammonia (NH3) and the emission of nitrous oxide (N2O), which reduce the efficiency of pig slurry (PS) as source of N to crops, besides adversely affecting the environment, human and animal health. Among strategies under investigation in other countries to mitigate these problems includes the injection of PS in soil and the use of nitrification inhibitors. In Brazil, the research in this area is still in initial stages. Therefore, the aim of this study was to evaluate the efficiency of injecting PS into the soil and the application of nitrification inhibitor dicyandiamide (DCD) in reducing N losses through volatilization of NH3 and N2O emissions in no-till corn. The study was conducted from December 2011 to May 2012 at the Federal University of Santa Maria and the treatments were: T1-control; T2-urea-N + PK; T3-PS surface; T4- PS surface + DCD; T5-injected PS and T6- PS injected + DCD. The dose of DCD (10 kg ha-1) was mixed with PS (50 m3 ha-1) at the time of its application in the field. The application of PS increased emissions of N2O and NH3. Although the strategy of injecting the PS has been efficient in controlling of emissions of NH3, by reducing it to 97,5%, however, it increased N2O emissions by 49,4%, in comparison to the application of PS on soil surface. The application of DCD with PS reduced N2O emissions by 62,0% in surface application and by 69,3% when PS was injected while N loss through volatilization of NH3 was unaffected. The results of this study indicates that injection of pig slurry into the soil under no tillage, combined with the use of the nitrification inhibitor dicyandiamide, is an effective strategy to mitigate the potential pollution of the environment by PS, in addition to preserving the value of fertilizer as source of N to the plants.