The summer 2021-22 edition of CRDC's magazine, Spotlight, focuses on the cotton industry's progress under the PLANET. PEOPLE. PADDOCK Sustainability Framework.

The 2021 CRDC Grower Survey – out now and featured in this edition of Spotlight – shows that 18 months after its introduction, there is increasing awareness of PLANET. PEOPLE. PADDOCK. among growers, with a majority believing it is very important for the cotton industry.

While some sustainability targets are still in development, others are close to being reached. Growers have been hard at work, with significant investment and powered by world-class RD&E, to improve water use efficiency and pesticide use.

Some targets need further action from the industry. An increase in greenhouse gas emissions from cotton farms, due largely to inefficient use of nitrogen fertilisers (as outlined in the CRDC and Cotton Australia 2019 Sustainability Report) is of concern and a key focus for CRDC's research, development and extension.

In line with our commitment to improve sustainability outcomes, we recently held the first meeting of the Australian Cotton Sustainability Reference Group. And, we’re about to kick off the fourth independent environmental assessment of Australian cotton, continuing the 30 year commitment to openly and transparently assessing our impact.

In 2022, CRDC invited its key partners to provide feedback on the health of the partnership with CRDC via stakeholder survey, to identify what's working effectively and to highlight the opportunities for strengthening the partnership. This report outlines the findings. This process will be repeated in 2025 to ensure continuous improvement.

Background

The project ‘Feasibility study of managed aquifer recharge [MAR] for improved water productivity for Australian cotton production’ is investigating the potential to implement MAR at a regional scale in established and emerging irrigated cotton growing regions of Australia. The broad aim of the project case studies was to evaluate how MAR might be feasible for irrigated cotton production and associated cropping systems in the focus regions, and make recommendations on further work to evaluate local hydrogeological conditions, plan the necessary site-specific infrastructure, and establish the legal, social and organisational conditions for implementation of MAR.

The focus of this report is the second case study of the MAR feasibility project, the Gilbert River Agricultural Precinct (GRAP) in the Gilbert River catchment. The study has concentrated on identifying how potential interventions that might provide timely and reliable water yields from the alluvial bed sands adjacent to the Gilbert River might work, and what information would be needed to support investment in the sustainable active management of bed sands.

The broad approach taken was to draw on evidence from a holistic feasibility assessment to scope the most promising opportunities (“scenarios”) for MAR, within an active management paradigm, and to test and refine these scenarios with local stakeholders and state government stakeholders. The key questions we have addressed in the context of seven feasibility criteria are:

1. How might potential strategies (e.g., leaky weirs, recharge weirs, infiltration basins) be applied in the Gilbert River to maximise storage, top up and/or slow down drainage from the bed sands to provide water for irrigation when needed?

2. What are the policy and implementation implications of active management of bed sands? What environmental, social and/or hydrological impacts would need to be tracked?

3. How could an active management approach operate? What governance and information sharing arrangements might be needed?

In addressing these questions, we have identified limitations in the current conceptualisations used in the models underpinning Water Resource Plans (WRP) for the Gulf catchments and, from this, opportunities to improve conceptual understanding of the bed sands.

The initial phase of .the project was devoted to the selection and testing of analytical techniques for assessing total nitrogen and leaching losses, and gaseous losses of nitrogen by ammonia volatilization and denitrification following the application of urea to cotton. Total nitrogen loss was measured in microplots by determining the amounts of labelled fertilizer nitrogen recovered in plants and soil, and subtracting this from the amount originally applied. Ammonia loss was determined directly by a micrometeorological technique which determines the ammonia concentration gradient in the air above the cotton crop. Denitrification loss was calculated by subtracting the measured ammonia loss from the total nitrogen loss. The movement of 15N down the soil profile gave an indication of the importance of leaching loss.