Investment

In the southern cropping region of Australia (including South Australia and Victoria) a three-component program to tackle key challenges of 1) where, how and when to ameliorate sands; 2) evidence-based strategic and tactical management to sustain production potential; and 3) an integrated, multi-faceted approach to knowledge sharing and capability development.

Building upon past and current GRDC-supported research, this investment proposes a multi-layer approach to increase the efficiency and efficacy of soil amelioration on sandy landscapes and fully harness the new soil potential to maximise yield potential.

Previous research in increasing crop productivity in the sandy regions of the south (such as CSP1606-008RMX) has been instrumental in providing growers with the necessary tools to identify and overcome constraints to production. These projects have significantly raised awareness among growers regarding the constraints of high soil strength, water repellence and acidification. However, the methods used to identify these constraints require on-site visits and point samples, which can be time-consuming and inconvenient. This limitation makes it challenging to assess the extent of the constraints before implementing soil ameliorations. Consequently, the on-farm implementation can have mixed success, and some areas of the paddock may even become more vulnerable, resulting in reduced yields. Overcoming these challenges and unlocking the full potential of sandy landscapes requires spatial prediction of constraints and their response to tillage-based amelioration techniques. Another critical aspect to consider is the temporal relationship between constraints and their response to amelioration. Determining how long a consistent crop response can be expected from an amelioration and the appropriate interval between strategic tillage passes is crucial. Output 1 of this investment aims to address the challenges of where, how, and when to ameliorate sandy soils.

The successful implementation of soil amelioration has allowed growers to achieve unprecedented yield levels in constrained sandy environments across all types of seasons. Analysis suggests that ameliorated sands can push the yield frontier to remarkably high levels of water use efficiency (WUE), challenging previous assumptions. There are potential engineering and plant-based innovations that could further enhance the amelioration of constraints, and these avenues warrant further investigation. Output 2 aims to develop long-term strategic agronomic tools for effectively harnessing the new potential (i.e., water use and WUE) in ameliorated sandy landscapes.

Achieving and maintaining high levels of productivity after soil amelioration requires a sustained supply of nutrients. Experimental data indicates that some site years with diminishing yield responses to amelioration were actually under-supplied with nitrogen and, in some cases, phosphorus. It is possible that other nutrients may also limit yields at these high levels. Bridging the knowledge gap in identifying amendments that provide adequate, timely and sustained sources of nutrition is essential. The season-dependent nature of this response makes it challenging to predict the right source, placement, and rate of nutrient supply. Therefore, post-amelioration management issues pose a significant barrier to the implementation of amelioration techniques. These issues encompass both the management of ameliorated sands and the management of the entire paddock. Output 3 proposes a regional approach to address the diverse range of issues identified through extensive industry consultation and produce tactical agronomic guidelines to maximise yields.