AS4419:2018 Soils for Landscaping and Garden Use

Owen Guy

Recent developments within the soil science industry and our understanding of how soil characteristics effect functionality. Led to changes in the Australian Standard 4419 – Soils for Landscaping and Garden use. These standards were developed to benchmark the necessary quality of general-purpose soils, top dressing, topsoil and landscaping mixes, for domestic and commercial use, supplied either in bulk or bagged lots. Following a thorough review, the Australian Standards Board have redesigned both the classifications of soils, analysis and requirements of each to reflect the end use of each soil category further.

The classifications consist of the following;

1. Landscape Soils (On Grade)
a. Low Organic Matter (Low/High Phosphorous variants)
b. Medium Organic Matter (Low/High Phosphorous variants)
c. High Organic Matter
2. Low-Density Media (On Slab)
a. Low Organic Matter (Subsoil)
b. Medium Organic Matter (Topsoil – Low/High Phosphorous variants)
c. High Organic Matter (Topsoil – Low/High Phosphorous variants)
3. Soils for Turf and Lawns
a. Underlay
b. Sports fields
c. Topdressing
4. Specialist Soils
a. Structural Filler
b. Wetlands Soil

Each classification specified under AS4419:2018 possesses a suite of analysis and required values to meet the standard. The category in which each soil product falls depends mostly on the organic matter content and phosphorous levels. The analysis necessary for AS 4419 has changed significantly, and it should be noted that soils previously analysed and assessed to AS4419:2003 are not automatically suitable according to AS4419:2018.

Another significant change to the requirements of the standard is the change with respects to the analysis of contaminants. In the previous version of AS 4419:2003 it was a requirement that samples be analysed for contaminants and satisfy the requirements for National or state guidelines for use and disposal of biosolid products. However, this requirement is no longer listed in AS4419:2018.

Within the revised version of AS4419, soils must be compliant with the ‘most current version of the state or territory guidelines for use in application to land’. This change in the contaminant guidelines for AS4419 requires some expertise to ensure that the correct guideline is used. There are many types, and versions of guidelines that may apply to a particular product and these vary from state to state (or territory).

What Does This Mean for Me?

The significant changes and new requirements of AS4419 are starting to become more and more prevalent within the industry as adoption begins to take traction. Soils are now characterised by end use, amount of organic matter and phosphorous levels. This needs to be taken into account when manufacturing soils or re-using site soils.

At a minimum, the desired end use must be known. This determines the analysis that is required to ensure that the soil meets the standard for the desired end use. The desired level of organic matter and phosphorous should also be known so that the correct target ranges can be applied. SESL can provide advice on the appropriate desired classification and ameliorants that can be used to achieve compliance with AS4419:2018.

When considering specifications previously provided by SESL or other companies, it is important to understand that AS4419:2018 supersedes AS4419:2003 and as such, the new suites of analysis must be applied. Compliance to AS4419:2018 has been provided as an update and improvement to AS4419:2003 so must be applied when certifying soils to 4419.

Contaminants are a strong talking point when discussing the changes of AS4419, as there has been some variability in the interpretation of the requirements of the standard. In SESLs opinion, it is essential that either raw materials or final blended products are assessed for chemical contaminants prior to analysis against AS4419:2018. The appropriate state or territory guidelines for the desired end-use of the product must be determined by a qualified environmental scientist to ensure that the correct guidelines are met to satisfy the requirements of the standard.

SESL has a team of both soil scientists and environmental scientists that are familiar with the changes in requirements to AS4419:2018. Our soil scientists have designed a range of packages that satisfy the required analysis for each of the new categories and are ready to provide advice on how to get your soil up to spec for AS4419:2018. Similarly, our environmental scientists are aware of the changes in the requirements for contamination according to the revised standard and are prepared to provide advice and assess soils to the most relevant state or territory guidelines.