Soil extension activities

WHY IS THIS PROJECT IMPORTANT

The project aims to give farmers a better understanding of their soils and how soils can be managed to improve production and water retention.

Soil issues in the Riverine Plains region are complex and can be segmented through the soil profile (i.e acidity may not be present at the surface but can be quite profound at 15cm depth). This means that soil testing needs to be comprehensive in order to understand where problems lie. 

Traditional soil testing at 0-10cm depth does not pick up deeper soil issues, however comprehensive soil mapping, ground truthing of soils and amelioration is expensive, and this has traditionally been a disincentive for farmers.

This project aims to support land managers by promoting the benefits of increased frequency and comprehensiveness of soil sampling and testing to inform soil management decisions and take action to improve soil health.

In short: Supporting farmers in soil testing and interpretation, mapping soil types, demonstrating soil amelioration techniques, establishing baselines for strategic decisions, and addressing soil constraints for sustainable, profitable farming.

Project focus

Two farmer discussion groups have been established, through which high priority soils issues such as sodicity, poor structure and low organic carbon levels will be identified.  Participants will be involved in soil testing and have the opportunity to engage with soil scientists at field walks, workshop and demonstrations designed to test and evaluate soil amelioration strategies such as lime incorporation and sub-soil incorporation of organic materials.

This project supports land managers and farmers to participate in soil testing and the interpretation of results. It aims to:  

• Improve knowledge and understanding of mapping and ground-truthing soil types in paddocks.
• Demonstrate innovative land management practices that protect and manage the soil resource in paddocks to improve efficiency, production and soil health.
• Improve the understanding of the value of soil data as an important part of land management decision making.
• Support land managers and farmers to contribute soils data to relevant national databases.
• Help establish baselines for current soil physical, chemical and biological status to provide a basis for farmers to make strategic decisions and identify future management practices, ameliorants and nutrient requirements to correct possible imbalances.
• Contribute to delivering sustainable, productive and profitable farm businesses.
• Improve farmers’ understanding and knowledge of soil constraints in paddocks and estimate the cost of the constraint to future production and water storage of soils.

Project outcomes

Results from the project's 2023 trials were published in Research for the Riverine Plains, 2024.

Key messages were:

• Segmented pH soil testing in problem paddocks can help farmers get a clearer picture of what is happening within each soil layer
• Many factors influence soil behaviour, so it’s important to understand your soil before making amelioration decisions
• Soil can have high levels of variability and this will play a role in choosing which amelioration options will suit best
• Once a soil constraint is identified, it is important to understand other soil characteristics before committing to deep incorporation of an ameliorant such as lime; some machines may go too deep and cause further issues, for example, by bringing up toxic sub-layers
• Where surface lime was applied, pH increased in the 0-5cm range only. The use of machinery incorporation resulted in a pH increase at depth, with a higher pH achieved as liming rate increased.

Learn more about the trial methods used, results and conclusions from the 2023 trials in the full article: Soil extension activities - Evaluating different rates of lime and incorporation techniques when ameliorating acid soils.

Smart farms small grants: soil extension activities – case study

Update

In early 2022 our farmer hosts identified paddocks with problem soils, determined through electromagnetic surveys. These sites were soil tested at 5cm increments, to understand the key constraints contributing to the issues seen above ground. The results were analysed by soil scientists and presented at our 2022 workshops alongside further discussion on acidic and sodic soils.

After these events, we asked local farmers and agronomists to join our discussion group for the project. This group allows farmers to follow what is happening in the trial more closely and be involved with decision making.

Our first discussion group worked through soil tests taken across the host farms in Rand, Buraja and Daysdale, sharing ideas on a treatment plan for the 2023 amelioration demonstration trial.

From the two paddocks selected to continue, one paddock had acidic soil, with high aluminum saturation and the other sodic soil (high percentage of sodium ions).

The result of the discussion was to focus the trials on different machinery options to incorporate various lime rates at the acidic site, and lime with various gypsum rates at the sodic site. The numerous machine options, speedtiller, deep offset discs, Lemken Rubion 10 and Horsch Tiger, will help provide further understanding and comparisons for product incorporation and depth, seed bed preparation and overall plant establishment.

The final treatment plan has been reviewed by soil scientists and shared with the discussion group. The next step is for the paddocks to be grid sampled for pH to assist with determining lime rates for the trial. A field walk was held at both sites in August 2023 to see the effects of the various treatments. Yield maps and post-harvest soil tests will be used to measure results at the end of the trial and presented at our final workshop in early 2024.

Acknowledgements

This project is supported through funding from the Department of Agriculture, Fisheries and Forestry through the Smart Farms Small Grants program and is co-funded by the Grains Research and Development Corporation.

It is delivered by Riverine Plains with partners AgriSci, Precision Agriculture and NSW Department of Primary Industries. Riverine Plains would like to thank farmer hosts, Roy and Michael Hamilton, Denis and Rebecca Tomlinson and Beau and Rebecca Longmire, for the use of their land and support throughout this trial.

Author: Rhiannan McPhee, Riverine Plains