Effect of reduced fertiliser rates in combination with a nitrification inhibitor (DMPP) on soil nitrous oxide emissions and yield from an intensive vegetable production system in sub-tropical Australia

Clemens Scheer1, Mary Firrell2, Peter Deuter2, David Rowlings1, Ian Porter3, Peter Grace1

1Institute for Future Environments, Queensland University of Technology, Brisbane, QLD 4000, Australia, [email protected]

2Department of Agriculture, Fisheries and Forestry (Queensland), Gatton Research Station, QLD 4343, Australia  

3School of Life Sciences, LaTrobe University, Bundoora, Vic 3083,Australia

Abstract

Vegetable production systems are characterised by intensive production with high inputs of nitrogen fertiliser and irrigation water. Consequently, high emissions of nitrous oxide have been reported. The use of nitrification inhibitors (NI) offers an effective method to reduce N2O emissions, whilst maintaining yield and increasing nitrogen use efficiency. However, only limited data are currently available on the use of NI in vegetable cropping systems. A field experiment was conducted to investigate the effect of the nitrification inhibitor 3,4-Dimethylpyrazol phosphate (DMPP) in combination with reduced N fertilizer application rates on N2O emissions and yield from a typical vegetable rotation in sub-tropical Australia. Annual N2O emissions ranged from 0.59 to 1.37 kgN/ha for the different fertiliser treatments. A 40% reduced fertilizer rate combined with DMPP reduced N2O emissions by more than half but achieved a comparable yield to the standard grower’s practice in two out of three crops. We conclude that DMPP shows a great potential for reducing N2O emissions from vegetable systems. However, further research is required to understand under what conditions reduced N rates of DMPP coated fertiliser are applicable and to determine the long-term effect of such a fertiliser regime over extended cropping cycles.