FERTILIZACIÓN NITROGENADA DE LARGO PLAZO EN MAÍZ CONTINUO: SU IMPACTO SOBRE LA CALIDAD DE RESIDUOS Y EL CARBONO ORGÁNICO DEL SUELO

MELCHIORI, R.J.M. NOVELLI, L.E., GREGORUTTI, V.C. ; CAVIGLIA, O.P.

Congreso; X Congreso Nacional de Maíz; 2014

Nitrogen fertilization increases maize (Zea mays L.) grain yield but reduces the C:N ratio of stover, which may affect the soil organic C (SOC) balance. This study evaluated the long-term effect of N fertilization on maize grain yield, stover quality in terms of its C:N ratio, and its effect on SOC. In addition, a simulation approach was used to account for the effect of stover quality on its mineralization and SOC balance. Maize grain yield, stover production and quality and SOC stock were measured from2006 to 2012) in a long term N fertilization experiment in Paraná, Argentina. On average, grain yield ranged from 5.06 in 2011 to 9.10 Mg ha-1 in 2009. The N effect on grain yield, significant in all seasons, was more important than the effect on C stover production. In contrast, stover C:N ratio showed a linear decrease as a function of N fertilization. Changes in the stover C:N ratio were inversely proportional to the difference between the N rate and the agronomical optimum N rate (AONR). Although N fertilization increased stover C inputs in 3 out of 6 yr, SOC stock remained unchanged. Simulation results indicate that the required stover amount to maintain the SOC stock increased as the C:N ratio decreased