Incorporation in soil and addition of enzyme inhibitor as a way to increase the efficiency of pig slurry and mineral fertilizer

The incorporation of nitrogen (N) fertilizers in the soil and the use of enzyme inhibitors (EI) can improve the efficiency of N fertilization by reducing losses by ammonia volatilization and nitrate leaching. This study aimed to evaluate the efficiency of EI addition and fertilizer incorporation on both grain and dry mass yields of corn as well as on some soil chemical properties, with focus on N availability. A field experiment was carried out for three years in randomized blocks with four replications. The treatments consisted of a 2 x 5 factorial, including two forms of fertilizers application: superficial (SUP) and incorporated (INC), allocated in the plots; and five fertilizations: mineral fertilizer (NPK); NPK + EI; pig slurry (PS); PS+EI; and control (TEST), allocated in the subplots. The soil mineral N content was determined at 30, 60, and 90 days after fertilizer application (DAA) and these times were considered as sub-subplots. All fertilizers increased the dry corn matter and grain yields and the soil availability of N, P, and K, mainly in the upper layer (0.00-0.05 m). However, only the PS promoted higher productivity when incorporated into the soil relative to the soil superficial application. The incorporation of fertilizers increases soil available P but has little effect on soil mineral N. The EI addition to the fertilizers promotes higher soil mineral N contents in the soil until 30 and 60 DAA respectively when superficially applied and soil incorporated, although this does not increase the corn productivity.