Dr Kirsten Verburg1, Dr Heather Pasley2, Mr Jody Biggs2, Dr Iris Vogeler3,4, Dr Enli Wang1, Dr Henrike Mielenz5, Dr Val Snow6, Dr Chris Smith1, Dr Chiara Pasut7, Dr Andrea Basche8, Dr Di He1, Dr Sotirios Archontoulis9, Dr Donald Gaydon2, Neil Huth10, Mr Dean Holzworth10, Dr Joanna Sharp11, Dr Rogerio Cichota11, Dr Edith Khaembah11, Dr Edmar Teixeira11, Hamish Brown11, Dr Mark Farrell7, Dr Chelsea Janke7,12, Dr Vadakattu Gupta7, Dr Peter Thorburn2
1CSIRO Agriculture & Food, Canberra, Australia, 2CSIRO Agriculture & Food, St Lucia, Australia, 3Aarhus University, Tjele, Denmark, 4Christian-Abrechts University, Kiel, Germany, 5Julius Kuhn Institute, Braunschweig, Germany, 6AgResearch Limited, Lincoln, New Zealand, 7CSIRO Agriculture & Food, Glen Osmond, Australia, 8University of Nebraska – Lincoln, Lincoln, USA, 9Iowa State University, Ames, USA, 10CSIRO Agriculture & Food, Toowoomba, Australia, 11Plant & Food Research Limited, Lincoln, New Zealand, 12University of Queensland, St Lucia, Australia
Biography:
Dr Kirsten Verburg is principal research scientist and project leader in CSIRO Agriculture and Food. She applies her skills in soil and cropping systems modelling to improve the understanding of soil water and nitrogen dynamics in agricultural systems. This supports the development of management strategies and monitoring designs that improve agricultural productivity and reduce off-site environmental impacts. Applied research for growers and advisors is an important driver for her work. The projects she leads often combine different science disciplines and aim to translate scientific research into information that allows industry to better support decision making.
Abstract:
The Agricultural Production Systems sIMulator (APSIM) has been used to explore a range of agricultural system questions, including those relating to nitrogen (N) cycling. With future sustainability focussed applications (e.g., assessment of N loss from Australian grains systems) we embarked on a detailed review of APSIM’s soil N modelling capability to inform and prioritise future development needs. Being 25 years since the release of APSIM’s soil N and residue modules, we could draw on 106 model verification studies across a wide range of systems, applications, and processes. APSIM displayed strong performance across all modelled processes, despite limited changes to the core of the soil N model since its inception. The model’s conceptual pool approach to modelling carbon (C) dynamics with N cycling linked to that via C:N ratios, has proven versatile but has also posed challenges relating to initialisation methods and returned organic C from the crops. Flow-on effects on the resulting sensitivity of predictions at different time scales, e.g. long-term C trajectories vs. short-term seasonal N loss studies need to be considered when using APSIM in scenario analyses. APSIM's prototypes for ammonia volatilization and N in runoff add N loss pathways that were until recently ignored but these do require further testing. The review highlights the importance of broad model evaluations across a wide range of applications to ensure their robustness, to identify issues that may be masked in single studies, and to allow the emergence of solutions with broad applicability. We illustrate these findings with case studies from the review.