Legume crops are one of key rotation components in agricultural systems, supplying nitrogen (N) to following crops and potentially increasing farm profitability. However, with the increasing atmospheric greenhouse gas concentrations, Australia will become warmer and dryer in the future. This greatly threatens Australian crop production and brings uncertain impacts on the profitability of adding legumes into non-legume crop sequences. In this study, we optimised the crop model, APSIM, using 4-year experimental data, collected in Wagga Wagga, New South Wales, Australia. The optimised model was then used to predict lupin biological N2 fixation (BNF) and the contribution of fixed N to the subsequent canola under historical and future climatic conditions in the rainfed cropping systems. The simulation results showed that, when there was no N fertilizer applied to canola in lupin-canola rotations, BNF increased about 3% by 2071-2100 under the higher greenhouse gas emission scenario, comparing to 1961-2000. This results in about 20% of increase in the contribution of lupin fixed N to the subsequent canola seasons (NC). However, these benefits will be reduced to zero when N fertilizer applied in canola seasons is over 40 kg N/ha for BNF and 60 kg N/ha for NC, respectively, by 2071-2100 for RCP8.5. This indicates that future climate change would enhance the N contribution of legume fixed N to subsequent crops only when the non-legume crops received lower N fertilizer in the legume added rotation cropping systems.
|Title of host publication||Proceedings of the 19th Australian Agronomy Conference|
|Subtitle of host publication||Cells to satellites|
|Publisher||Australian Society for Agronomy|
|Number of pages||4|
|Publication status||Published - 2019|
|Event||19th Australian Agronomy Conference - Wagga Wagga Civic Theatre, Wagga Wagga, Australia|
Duration: 25 Aug 2019 → 29 Aug 2019
|Conference||19th Australian Agronomy Conference|
|Abbreviated title||Cells to Satellites|
|Period||25/08/19 → 29/08/19|
|Other||The 19th Australian Agronomy Conference will be held in Wagga Wagga, NSW from|
25 – 29 August 2019. In the heart of the Riverina, Wagga Wagga has a range of rural industries across the region. Wagga has everything to offer the agronomy conference being surrounded by a mixed farming zone with irrigation to the west and permanent pasture enterprises to the east.
The conference theme Cells to satellites highlights the integrative nature of agronomy. Each of us work across a range of disciplines to optimise crop or pasture production for productivity and profitability. We have an increasing number of tools available to increase the precision and accuracy of our work; whether it is at the “cellular” level where DNA is mapped and biochemistry is unravelled or using “satellites” for remote sensing or guidance. The opportunities for enhancing our agronomy research is boundless.