RRRD056 Progress update

November 2012

RRRD056: Evaluating and improving A-Class practices to control nutrient losses from sugarcane

Science Summary:

-  Testing improvements in fallow crops involved the measurement of water and nutrient loss during cowpea crop, destroying the cowpea and establishing the cane crop. The biomass and N concentration of the cowpea was measured and was reasonably high (110-115 kg/ha). It was suggested application of 130 kg/ha on N following a cowpea crop of this size but, after consultation with the farmer and the Project Catalyst ‘Precision Planner’ it was agreed that the N in the legume could be almost enough to meet the sugarcane crop’s requirements. Thus, only 36 kg/ha of N was applied to this treatment (giving total N inputs of ~150 kg/ha). This approach is consistent with the concept developed in the N Replacement system1 and so clearly represents A-Class management.

-  Pilot analyses have been completed on the Mackay data based on the simulation output of Biggs et al. (2012), with the A to D management classes decoupled. Comprehensive statistical methods are currently undertaking simulations of the individual practices (e.g. fallow management, tillage, N applications) in each region.

-  Overhead low pressure (OLP) irrigation is being compared with traditional furrow irrigation. One advantage of OLP (and trickle) is that it is compatible with trash blanketing. Modelling to date has concentrated on verifying the model’s ability to simulate results from the experiment (cane yield, cane N export, soil mineral N, runoff water and N, and deep drainage water and N) in the three irrigation systems. Predictions of results are good. These simulations will define the water quality benefits of ‘best practice’ in both the furrow and OLP irrigations systems, thus identifying the potential water quality benefits of the OLP system.

Progress Update:

-  Activities and milestones progressing well.

-  Experiment site selection complete. There will be two sites (paired sites) established on three farms, one in the Herbert region and two in the Burdekin. All farms are under some form of ‘precision’ farming (i.e. A-Class practice) and the monitoring will address the degree to which nutrient applications can be reduced with precision farming

-  Plans for establishing a site in the Mackay region (monitoring mill mud) could not be carried through as all potential sites had mill mud and fertiliser applied before we could install monitoring equipment.

-  Modelling of three existing data sets that have come from experiments in previous projects has commenced. Modelling work has included parameterisation of soils, collation of meteorological data, formatting results, etc, and preliminary assessment of model predictions. Soil parameter files from two sites have been included in P2R modelling activities. Parameters from the third site will be included in the future.

-  We are awaiting laboratory results of water samples to indentify water quality benefits of the A-Class practices. Measurements are underway for the 2012-13 year. Model parameterisation is awaiting results from the field site.

-  Communication protocols with Regional Bodies have been finalized, and awareness raising activities commenced. These activities have been presentations at the Project Catalyst Mackay Whitsunday Regional Grower Event, Cane E&E strategy meeting and the Reef Rescue Regional Cane Industry Working Group meeting. Details of project’s progress were communicated to Regional Bodies at three formal meeting (described above), and numerous non-on-one interactions.