Nitrous oxide and methane emissions from soil and nitrogen uptake by eucalyptus fertilized with enhanced efficiency fertilizers

Evaluate which nitrogen fertilizer alone or in combination with additives for enhanced efficiency can reduce N2O and CH4 emissions of soil cultivated with eucalyptus and also increase nitrogen uptake. A pot experiment with eucalyptus seedlings was conducted with the application of urea or ammonium sulfate alone or in combination with polymer coatings, with nitrification inhibitor dicyandiamide (DCD), or with urease inhibitor N-(n-butyl)-thiophosphoric triamide (NBPT, only with urea). The sampling of gases and soil parameters was carried out over a 163-day period, and at the end of this period plant attributes were evaluated. When added to urea or ammonium sulfate, DCD reduced N2O emission by >95%, increased CH4 uptake by 11–20%, and increased the nitrogen uptake by eucalyptus by 27–30%. Meanwhile, polymer coated urea, polymer coated ammonium sulfate, or NBPT added to urea did not change these parameters. Ammonium sulfate alone reduced N2O emission by 38% and increased nitrogen uptake by 23% relative to urea alone. DCD mixed with urea or ammonium sulfate effectively reduced soil N2O emission and increased nitrogen uptake by eucalyptus plants; while polymer coatings or NBPT did not. Among the pure sources, ammonium sulfate was more efficient at reducing N2O emission and increasing nitrogen uptake compared with urea; but when DCD was added, N2O emissions were similarly low for both sources.