Extending “SafeGauge for Nutrients” to high rainfall cropping in Australia

Kirsten Barlow1, Thabo Thayalakumaran2, Philip Moody3

1 Agriculture Victoria, DEDJTR,124 Chiltern Valley Road, Rutherglen, Victoria, 3685, Kirsten.Barlow@ecodev.vic.gov.au

2 Agriculture Victoria, DEDJTR, 32 Lincoln Square North, Carlton, Victoria, 3053

3 Department of Science, Information Technology and Innovation, Brisbane, Queensland, 4000


As agricultural systems continue to intensify there is a need for farmers and farm advisors to understand how soil, climate and management interact to affect nitrogen (N) losses at the paddock scale. Computer-based decision support tools have been widely used to build farm advisors’ capacity to understand the risks of N losses to the environment. However, existing tools often only provide an average annual risk of nitrogen loss from a paddock, even though nitrogen export is dependent on daily interactions between soil water content, water movement through deep drainage and runoff pathways and N availability. In this paper we present the design of a decision support tool for high rainfall cropping systems building on SafeGauge for Nutrients (developed for the sugarcane industry in Queensland, Australia). This tool (SG_Grains), allows users to define the system including location, cropping season, soil type and management decisions (e.g. fertiliser rate and timing, cultivation, stubble management). Information on management practices is combined with relevant modelled daily crop growth, soil water, drainage and runoff sourced from a library of simulation runs for various soil types and climates. Taking account of  N uptake and cycling, the daily nitrogen balance and risks of nitrogen losses via the various pathways are calculated. The risks are then modified to account for differences in slope and paddock position in the landscape. The results are presented as a risk gauge for all three loss pathways (runoff, leaching and denitrification), as well as a summary report on nitrogen input/output balance for the selected paddock. SG_Grains will be used as part of the training for advisors within the Fertcare Program, allowing the investigation of how management affects the risk of N export through various pathways.