The effect of cattle slurry in combination with nitrate and the nitrification inhibitor dicyandiamide on in situ nitrous oxide and dinitrogen emissions

[摘要] A field study was conducted to determine the effect of the nitrificationinhibitor dicyandiamide (DCD) on N₂O and N₂ emissions after cattleslurry (CS) application in the presence of nitrate (NO₃) fertiliser onseven different occasions (between March 2009 and March 2011).N₂O emissions from CS in the presence of NO₃ fertiliser were veryhigh (0.4–8.7% of applied N) over a 20-day period, under mild moistconditions. Emissions were significantly larger from the CS treatmentcompared to an NH₄⁺-N source, supplying the same rate of N as in theslurry. This study supports the view that organic fertilisers should not beapplied at the same time as nitrate-based fertilisers, as significantincreases in N₂O emissions occur. The average N₂O mole fraction(N₂O/(N₂O + N₂)) over all seven application dates was 0.34 forCSNO₃ compared to 0.24 for the NH₄ClNO₃ treatment, indicatingthe dominance of N₂ emissions.The rate of nitrification in CSNO₃ was slower than inNH₄ClNO₃, and DCD was found to be an effective nitrification inhibitor in bothtreatments. However, as N₂O emissions were found to be predominantlyassociated with the NO₃ pool, the effect of DCD in lowering N₂Oemissions is limited in the presence of a NO₃ fertiliser. To obtain themaximum cost-benefit of DCD in lowering N₂O emissions, under mild moistconditions, it should not be applied to a nitrate containing fertiliser (e.g.ammonium nitrate or calcium ammonium nitrate), and therefore the applicationof DCD should be restricted to ammonium-based organic or syntheticfertilisers.

[学科分类] 地球化学与岩石