Scoping options for low-lying, marginal cane land to reduce DIN in priority wet tropics catchments
Led by: Dr Nathan Waltham, JCU
This project will explore alternative land use options to reduce nitrogen losses from marginal sugarcane land in priority wet tropics catchments. The Wet Tropics Water Quality Improvement Plan (WQIP) identified that complete adoption of sugarcane best management practices would be insufficient to achieve the nitrogen load reductions needed to meet the Great Barrier Reef (GBR) Water Quality Guidelines. We will map low-lying, marginal cane land with community and industry partners, identify possible alternate uses, quantify the economic costs and benefits of land transition (in terms of alternate income streams), identify constraints and opportunities for alternative land uses to reduce nitrogen.
The Reef 2050 Long-Term Sustainability Plan and Reef Plan 2013 have set ambitious targets for GBR water quality improvement. The Wet Tropics WQIP identified that in order to meet the GBR Water Quality Guidelines the ecologically relevant target for dissolved inorganic nitrogen (DIN) is between 70-80% in the priority wet tropics catchments such as Russell-Mulgrave, Johnstone, Tully/Murray and Herbert.
The key problem is even the complete adoption of ‘A-class’ sugarcane management practices is predicted to only result in around 30% reduction in DIN loads. Therefore there is a need for new, innovative approaches to reduce nitrogen loads, and that are fully costed.
How Research Addresses Problem
This project will explore and identify constraints and opportunities for innovative, cost-effective options for reducing nitrogen loads through alternative land uses that require no nitrogen application. There will be a focus on marginal, low-lying cane lands which pose a high risk of nitrogen loss through: waterlogging and associated nitrogen losses via the atmosphere, surface water and deep drainage; their proximity to receiving waters; and low productivity (and hence low nitrogen use efficiency).
The project will generate GIS maps of low-lying, marginal land in the priority wet tropics catchments which are the focus of the Queensland Government’s major integrated project (e,g, Russell-Mulgrave, Johnstone, Tully/Murray or Herbert catchments). A literature review will identify possible options, based on the success of similar initiatives around the world e.g. alternative production (e.g. forestry), fallow based on climate forecasting, conversion to wetlands or other natural ecosystems etc. Stakeholders will be engaged to discuss options for the low-lying land based on existing information on geology, agricultural productivity, groundwater levels, saline intrusion etc. An economic assessment of the options will then provide at-source cost/benefit curves for priority project areas that will maximise GBR water quality improvement.
A major strength in this research project is that it will also quantify potential future income streams such as carbon, water quality credits and rate rebate options as part of this land transition. This will identify new levers for encouraging change. The wet tropics WQIP identified that adoption of A class practices would come at a cost to growers and would require significant investment. Therefore alternative uses of marginal land that may be more economically viable and significantly reduce nitrogen loads would have multiple benefits. This is a key delivery in this project, determining whether identified options are economically viable and as such the feasibility of their implementation.
Alignment with NESP Research Priorities
This project addresses priority 1 of NESP TWQ:
- Local scale identification of priority contaminant export loss for better targeting on-ground works and extension activity.
- Develop/evaluate practical methods for ‘off farm’ nutrient and sediment loss mitigation and capture.
- Compare the ability of different social and/or economic levers to encourage practice change in different contexts.
Water quality; Nitrogen; System repair; Wet tropics; Economics.
This project is jointly funded through JCU, GU, GBRMPA, DEHP and the Australian Government’s National Environmental Science Programme.
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