Over the last few years there has been increased talk about the role that agriculture plays in nitrous oxide (N20) emissions however, limited research has been conducted around the grains industry’s contribution to emissions.
Already farmers have begun to use nitrogen more efficiently by including leguminous break crops in their rotations and taking a more prescribed approach to nitrogenous fertiliser applications that better match crop demand and the seasonal conditions. But how much N20 is being emitted from soil remains unclear.
This year, in conjunction with DAFF, the Department of Primary Industries (DPI) and the Low Rainfall Collaboration Group (LRCG), BCG is managing two demonstrations that will attempt to measure N2O emissions from soils under varying cropping regimes.
The first will compare the N2O output when nitrogen is applied through synthetic fertiliser. The second will measure the N contribution made by a vetch legume crop that is terminated at various times in the establishment year and the corresponding effect of N2O emissions from a non-legume crop in the subsequent season will also be measured.
In order to compare these management options on a greenhouse gas basis, N20 emissions will be measured from PVC cylinders of 30cm diameter which have been installed in between the crop row. N20 gas will be extracted via medical syringes into air evacuated viles at sampling intervals of one day prior, one day after and one week following a rainfall event. Collected samples will be sent to Melbourne University for analysis.
If N2O is released to the atmosphere; nitrogen has not been used by the crop, which ultimately means that input dollars have been wasted.
The main aims of this demonstration are to: increase farmer knowledge about the N2O emissions made from fertiliser and legumes; reveal options available to reduce N20 emissions; and to provide information about nutrient use efficiency that maximises productivity.
Additionally, growers and advisors will have a better understanding about how nitrogen application in the system can deliver the best result in terms of production per tonnes of carbon dioxide equivalents (CO2e) emitted.
