Nitrous oxide emissions from grain production systems across a wide range of environmental conditions in eastern Australia

Abstract

Abstract. Nitrous oxide (N 2 O) emissions from Australian grain cropping systems are highly variable due to the large variations in soil and climate conditions and management practices under which crops are grown. Agricultural soils contribute 55% of national N 2 O emissions, and therefore mitigation of these emissions is important. In the present study, we explored N 2 O emissions, yield and emissions intensity in a range of management practices in grain crops across eastern Australia with the Agricultural Production Systems sIMulator (APSIM). The model was initially evaluated against experiments conducted at six field sites across major grain-growing regions in eastern Australia. Measured yields for all crops used in the experiments (wheat, barley, sorghum, maize, cotton, canola and chickpea) and seasonal N 2 O emissions were satisfactorily predicted with R 2 = 0.93 and R 2 = 0.91 respectively. As expected, N 2 O emissions and emissions intensity increased with increasing nitrogen (N) fertiliser input, whereas crop yields increased until a yield plateau was reached at a site-and crop-specific N rate. The mitigation potential of splitting N fertiliser application depended on the climate conditions and was found to be relevant only in the southern grain-growing region, where most rainfall occurs during the cropping season. Growing grain legumes in rotation with cereal crops has great potential to reduce mineral N fertiliser requirements and so N 2 O emissions. In general, N management strategies that maximise yields and increase N use efficiency showed the greatest promise for N 2 O mitigation.

Greenhouse Gas Emissions From Cropping and Grazed Pastures Are Similar: A Simulation Analysis in Australia

“…For simulation of SOC with APSIM described in (1), close correspondence with measured values was obtained in these references for experimental periods of up to 44 years with RMSE values of 1 to 11 Mg SOC ha −1 (0.0-0.3 m). Close correspondence of simulated and measured seasonal N 2 O emissions was also demonstrated with RMSE values of 0.052-0.441 kg N ha −1 (Mielenz et al, 2016) and with simulated emissions within ±10% of measured values (Meier et al, 2017). While these publications demonstrate the credible simulation capacity of these tools, the simulations are not for the precise locations of the case study farms and do not use the model set ups described in these publications.…”

“…Simulation tools have been validated in other studies for (1) APSIM crop and pasture systems (Carberry et al, 2009;Pembleton et al, 2013;Meier et al, 2017) including simulation of SOC and N 2 O emissions in similar soils and climates (Luo et al, 2011;Liu et al, 2014;Mielenz et al, 2016;O'Leary et al, 2016); and peer-reviewed application of (2) the Feed Demand Calculator (Bell et al, 2008;Moore et al, 2009); and (3) S-GAF and B-GAF (Browne et al, 2011;Harrison et al, 2014a,b). For simulation of SOC with APSIM described in (1), close correspondence with measured values was obtained in these references for experimental periods of up to 44 years with RMSE values of 1 to 11 Mg SOC ha −1 (0.0-0.3 m).…”

Modelled Quantification of Different Sources of Nitrogen Inefficiency in Semi-Arid Cropping Systems

“…These modules are described on the APSIM website (www.apsim.info, accessed on 7 June 2021) and are well-validated for wheat growth and development [31] and the simulation of soil water and N dynamics [32,33]. The ability of APSIM to simulate N cycling and losses has been specifically validated against field data for leaching [31] and denitrification [33,34], and numerous studies have demonstrated its relevance to commercial crops in southeast Australia [35][36][37].…”

Sustainable intensification with irrigation raises farm profit despite climate emergency

“…T A B L E 2 Details of crop type, sowing date, irrigated farm area and level of nitrogen fertiliser input for 16 scenarios combining four wholefarm adaptations (Baseline, Diversified, Intensified and Simplified) and four irrigation infrastructure types (Gravity, Pipe & Riser, Pivot and Drip) (adapted from Monjardino et al, 2022, and Whole Readers are directed to other works (Bilotto et al, 2021;Mielenz et al, 2016;Rathnappriya et al, 2022;Robertson & Lilley, 2016) for sensitivity effects of nitrogen on crop growth.…”