Quantifying the variability of the effectiveness of nitrification inhibitors on N2O emissions (P21 lysimeter trial)
Authors: CAM de Klein, K C Cameron, H J Di, J Guo, R R Sherlock
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Executive summary
Recent research has shown that DCD can substantially reduce N2O emissions from urine patches and grazed grassland with reduction potentials ranging from 60 to 80% (Di and Cameron 2002; 2003; 2006; Di et al. 2007; Smith et al. 2008a; 2008b)1. The research to date has been largely conducted on Canterbury soils (Lismore and Templeton) with some additional measurements made on two North Island soils (Taupo Pumice and Waikato Horotiu) and one Southland soil (Pukemutu). Although the results to date suggest similar N2O reduction potentials from urine patches among these soils, a recent independent review for the PGGRC (Pastoral Greenhouse Gas Research Consortium) recommended that more research on the effectiveness of DCD should be conducted in a wider range of soil types and under different climatic conditions. Rainfall or irrigation is one of the key environmental drivers for N2O emissions. In addition, rainfall/irrigation can displace DCD down the soil profile, away from where it is most effective, but very little is known about the impact of the rate of displacement of DCD on its effectiveness. Movement of DCD is largely dependent on the interaction of soil structure and rainfall/irrigation intensity.
Recently, the Pastoral Research Programme - Environment (P21) commenced a nitrification inhibitor programme of work, which includes detailed lysimeter studies investigating the effect of DCD displacement on reducing nitrate leaching in 6 different soils under two rainfall/irrigation regimes. Thus, there is a unique opportunity to use this N leaching study to also study the effectiveness of DCD on N2O emissions – and hence the use of DCD as a mitigation strategy.
1 Di HJ and Cameron KC (2002) Soil Use and Management 18, 395-403; Di HJ and Cameron KC (2003) Soil Use and Management 19, 284-290; Di HJ and Cameron KC(2006) Biology and Fertility of Soils 42, 472-480; Di HJ, Cameron KC and Sherlock RR (2007) Soil Use and Management 23, 1-9; Smith LC, de Klein CAM, Monaghan RM, Catto WD (2008a) Australian Journal of Experimental Agriculture 48, 160-164; Smith LC, de Klein CAM, Catto WD (2008b) New Zealand Journal of Agricultural Research (in press)
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