Project Title
Root growth and uptake in constraining subsoils
Project Leader
Dr Mac Kirby
Organisation
CSE
APSRU Representative
Brian Keating
Funding Body
GRDC
Administration Contact
Ms Kathy Heinze
Organisation: TBA
Ph: Fax:
Commencement Date
1 July 2000
Completion Date
30 June 2003
Research Proposal Summary
Aims
§ direct observation and measurement of root growth and uptake, using X-ray imaging and water uptake monitoring of growing roots, in several subsoils with identified constraints, compared and contrasted with the same subsoils manipulated to remove or modify the constraints;
§ test of the efficacy of current root growth and uptake models to predict the directly observed behaviour; and, as required,
§ new routines, developed using the directly observed behaviour and tested in the field, to predict root growth and uptake.
Potential Outcomes
The project addresses the priorities set out under section 3.4.2 of the GRDC Research Prospectus, in particular, “innovative ways of enhancing crop performance on soils with hostile subsoil” and, to a lesser extent, “understanding the biology of the soil-root interface”.
These priorities were explored in detail at the July 1999 workshop “Innovative Approaches to Overcoming Subsoil Constraints”, at which the proposed project supervisor, Mac Kirby presented work associated with this proposal. This project addresses directly the first two gaps in current knowledge noted in the workshop summary, given by John Passioura. These were: “what are the roots seeing?”; and hydrology, which in part was the interaction of roots with macropores and throttles. The proposed project has been discussed with Ian McClelland of the Birchip Cropping Group, who is supportive and with Matt McCallum and John Kirkegaard of CSIRO Plant Industry and Chris Smith of CSIRO Land and Water, with whom (amongst others) the project might collaborate in the Temora/Bland or Wagga regions.
The planned outcome is: improved management options for overcoming, and enhanced knowledge and capacity to predict the production and environmental consequences of, subsoil constraints to root growth and uptake.
Milestones
Milestone X: Description and criteria:
Annual report to GRDC describing:
§ Completion of field monitoring of 1 seasons root growth and water use, including measurement of water use in 2 vertical soil profiles at a minimum of 8 depths using TDR methods. Samples taken at three depths in each treatment at two times for both X-ray image analysis and core washing.
§ Completion of sampling at Birchip to obtain soil for root growth and X-ray imaging trials
Milestone Y: Description and criteria:
Annual report to GRDC describing:
§ Interpretation of root growth and water use in the field experiment, giving quantitative relations between root growth and water use.
§ Completion of growth and X-ray imaging trials involving the growth of roots in at least one soil type (Birchip) and only one constraint (no interactions between root growth constraints): ie, +/- subsoil macropore structure, +/- chemical constraint (sodicity and/or boron constraint), +/- biological constraint (+/- sterilisation). Image and water use data interpreted and tabulated from these experiments.
Milestone Z: Description and criteria:
Final report to GRDC describing:
§ Completion of the 2nd set of growth and X-ray imaging trials involving the growth of roots in at least one soil type (Birchip) with interaction between macropore structure and chemical and biological constraints: ie + subsoil physical constraint (no macropore structure), chemical constraint (sodicity and/or boron constraint) and biological constraint present in all combinations of pairs, and all three together. Image and water use data interpreted and tabulated from these experiments.
§ Summary and overview of the full field and lab root growth and X-ray imaging work (ie, synthesising the work reported in the two previous annual reports).
§ Test of a current root growth model (within APSIM) to simulate the data gained in the experimental part of the program. The objective measure is quantified statistical performance of the model, including quantified variation of input root growth parameters. Since current root growth models do not incorporate subsoil structural effects of the kind we are now observing, we expect the model will be found wanting. It this is the case then:
§ Development and test of an improved root growth model that can simulate subsoil - root growth interactions. The objective measures are: 1. A documented algorithm; 2. A set of statistical tests describing the performance and 3. Application to an example of the likely consequence over a run of years (ie variable weather) of modifying subsoil constraints (in a manner suggested as potentially useful by the root growth and X-ray imaging work) in the Birchip region.
Budget
Resource Requirements & Contributions
Prior Provision of IP & Rights of Ownership
Ownership, equity in and use of IP to be developed
C
Rights of Publication
Joint
Strategic Plan Goal No.
4
Relevance to Strategic Plan
Linked