Dicyandiamide as nitrification inhibitor of pig slurry ammonium nitrogen in soil

Dicianodiamida como inibidor da nitrificação do nitrogênio amoniacal de dejetos líquidos de suínos no solo

ABSTRACT:

Inhibition of nitrification of ammoniacal nitrogen pig slurry after its application to the soil can mitigate nitrogen (N) losses by nitrate (NO₃ ^-) denitrification and leaching, with economical and environmental benefits. However, the use of this strategy is incipient in Brazil and, therefore, requires further assessment. The aim of this study was to evaluate the efficiency of dicyandiamide (DCD) nitrification inhibitor in slowing the nitrification of ammoniacal N applied to the soil with pig slurry (PS). For this, incubation was performed in laboratory, where nitrification was assessed by NO₃ ^- accumulation in the soil. Rates of 2.8, 5.7 and 11.3kg DCD ha^-1 were compared, being applied to the soil during PS addition. Nitrification was inhibited by DCD, and inhibition magnitude and duration depended on DCD applied rate. At a dose of 11.3kg ha^-1 DCD, nitrification was completely inhibited in the first 12 days. During the first month after PS application, each 2.8kg of DCD increase applied per hectare promoted NO₃ ^--N reduction in the soil of 13.3kg ha^-1, allowing longer ammoniacal N maintenance in the soil.

Key words:
nitrogen oxidation; DCD; nitrogen dynamics