Inhibition of nitrification process by seed oil from Acrocomia totai palm tree

Nitrification inhibitory properties of plant substances offer potential benefits for agricultural applications. In this study, hexane-extracted seed oil, and 10, 20, and 30 mg/pot dry powder of seed exocarp and mesocarp from Acrocomia totai were applied in a quick nitrification bioassay for 24 or 50 hr, as well as for 4 weeks laboratory soil incubation, to investigate their effects on nitrification process. Results showed that applied oil concentrations significantly reduced nitrification rates. The extent of inhibition was increased with the oil concentrations from 5 to 25 µl in both experiments. The exocarp and mesocarp powders also inhibited nitrification, but it was not as high as oil-induced inhibition. Analysis of oil fatty acids showed that oil consisted of 71%, 26%, and 3% of saturated, monounsaturated, and polyunsaturated fatty acids, respectively. This suggests that fatty acids or some unknown ingredients in crude oil could be the responsible inhibiting compound.