Nitrification and urease inhibitors have been used to reduce nitrous oxide (N2O) emissions and increase nitrogen use efficiency in many agricultural systems. However, their agronomic benefits, such as the improvement of grain yield, is uncertain. A two-year field experiment was conducted to (1) investigate whether the use of 3,4-dimethylpyrazole phosphate (DMPP) or N-(n-butyl) thiophosphoric triamide (NBPT) can reduce N2O emissions and increase grain yield and (2) explore the financial benefit of using DMPP or NBPT in a rain-fed cropping system in south-eastern Australia. The experiment was conducted at Wagga Wagga, New South Wales, Australia with wheat (Triticum aestivum L.) in 2012 and canola (Brassica napus L.) in 2013. Results showed that urea coated with DMPP reduced the cumulative N2O emission by 34% for a wheat crop in 2012 (P < 0.05) and by 62% for a canola crop in 2013 (P < 0.05) compared with normal urea, but urea coated NBPT had no effect on N2O emission for the wheat crop in 2012. Neither nitrification nor urease inhibitors increased crop yields because the low rainfall experienced led to little potential for gross N loss through denitrification, leaching or volatilisation pathways. In such dry years, only government or other financial incentives for N2O mitigation would make the use of DMPP with applied N economically viable.
Organic Manures and Crop Residues as Fertilizer Substitutes: Impact on Nitrous Oxide Emission, Plant Growth and Grain Yield in Pre-Monsoon Rice Cropping System
