Dr Kirsten Verburg1, Dr Ketema Zeleke2, Dr Sarah Rich3, Dr John Broster2, Dr Chao Chen3, Dr Tao Luo3, Neil Huth4, Mr Dean Holzworth4, Dr Therese McBeath5, Dr Phil Eberbach2, Tony Swan1, Mr James Holding6, Mr Greg Condon7, Kirrily Condon7
1CSIRO Agriculture & Food, Canberra, Australia, 2Charles Sturt University, Wagga Wagga, Australia, 3CSIRO Agriculture & Food, Floreat, Australia, 4CSIRO Agriculture & Food, Toowoomba, Australia, 5CSIRO Agriculture & Food, Glen Osmond, Australia, 6Farmlink, Temora, Australia, 7Grassroots Agronomy, Junee, 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:
Early sowing to improve crop water use efficiency and dry sowing to accommodate larger programs, along with changes in autumn rainfall patterns, have prompted Australian grain industries to consider a range of innovations intended to improve crop establishment and early vigour. The ability to predict near-surface soil environmental conditions (i.e., soil water and temperature to ~ 25 cm depth) in the period leading up to sowing and early in the crop growing season is critical to the development and evaluation of many of these strategies. For example, deep sowing or deep fertiliser application rely on the subsurface soil to be wetter than the surface soil, so it is important to assess how often this occurs. Residue management aims to create differences in evaporative demand, potentially changing both soil water and temperature dynamics in the near-surface soil, but how much difference can it make?
In this presentation we reflect on our experiences with modelling the near-surface soil environmental conditions across several projects focussed on deep fertiliser application, stubble management, and deep sowing. We share lessons from model testing of APSIM Next Generation (SoilWat and SWIM3) using data from small plot and field experiments, as well as tests evaluating the sensibility of simulated dynamics. Getting value from model predictions relies on balancing modelling uncertainties with those introduced by field spatial variability and practical field management, while identifying broader emerging trends that identify the factors that drive the success or otherwise of different strategies.