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Sometimes it’s important to take a step back and simplify things down a little, and this post is focusing on a fun an educational experiment you can try at home with your children.

This article will take you through a simple experiment that you can do at home with some keen young minds and a few household items to test the pH levels of the soil in your own backyard. At a commercial level, geotechnical engineering and soil classification teams apply similar basic principles in order to classify the properties of various different soil samples, albeit in a more sophisticated and scientifically controlled manner.

The experiment will help you gauge the approximate pH level of your soil, and can then be used to guide you decisions about what is the best use for that particular area, in much the same way that an engineer would for an upcoming project.

The acronym “pH” stands for “power of hydrogen” and measures the level of hydrogen ion on a scale of 1 to 14, where a score of less than 7 is classified as acidic and a score of greater than 7 is considered alkaline. To provide some reference, vinegar usually scores a 3, whilst hand soap would score around a 10. Distilled water is pH neutral and scores a 7.

In order to determine a rough estimate of where your backyard soil sits on the pH scale, you will need to collect approximately 1 cup of soil, 2 containers or jars, some white vinegar, and some baking soda.

Alkalinity Test

Take a container or jar and place a couple of spoonfuls of the soil sample in each one. Slowly add water until the soil is just moist, and then add a tablespoon of white vinegar and check to see if any fizzing takes place. If you can notice some fizzing, this suggests that the soil is on the alkaline side of the scale i.e. above 7. If there is no fizzing, it is likely that your soil pH is acidic i.e. less than 7.

Acidity Test

The test for acidity levels is very similar. Take a fresh container and add the same amount of soil and water as in the previous test. Now mix a separate solution of 1 tablespoon baking soda and 2 tablespoons of water. Once this is combined, pour over the soil and check for signs of a fizzing reaction. A reaction will suggest that the soil is mildly acidic and no reaction suggests alkalinity.

Whatever the outcome of your soil test, there are a few simple remedies to try to balance the pH level in your yard and encourage better use of the space you have. For acidic soil, try agricultural lime to balance the pH, and for alkaline soil, add some organic mulch/compost. Alternatively, try researching some plants or fruit and vegetables that thrive naturally in slightly unbalanced soil.
This is a simple yet interesting test that gives some insight into the variety of different characteristics that soil can display and how this may affect potential usefulness of the area, and is very educational for any budding young scientists looking to explore some safe and easy experiments at home.

In order to provide a comprehensive and reliable guide to soil and landscape classification in Australia, the NSW Department of Land & Water Conservation have gone to great lengths to map out much of Eastern and Central New South Wales. You can read the original report produced by the DLWC here.

This project captures over 13 million hectares of agricultural and coastal land, aiming to provide a thorough analysis of soil and landscape profiles, where significant common characteristics can be identified. Large-scale classification projects such as this help to identify potential land use issues, as well as opportunities for further development.

Using a combination of field survey, full laboratory analysis and aerial assessment, large areas of land surface can be classified according the homogeneity of physical and mineral properties noted in the earth.

An extensive analysis such as the one carried out by the Department of Land & Water Conservation, provide interpretation of the usefulness of the land for both agricultural purposes, including the pH levels found in the soil, whereas geotechnical engineers will be more interested in the tests conducted on soil volume expansion propensity and particle size analysis.

By understanding the capabilities and limitations of land use in a specific area, informed decisions can be made on the progress or alternative options for any project where geological conditions may affect the feasibility of the project.

Looking toward the future, the NSW Department of Land & Water Conservation are aiming to further expand the usability of such extensive mapping initiatives, including the refinement of a database that provides digital information storage and allows researchers in the field to update quickly and more accurately.

The benefits of this collection of information on soil properties in New South Wales will flow on to many industries and government sectors. When looking to effectively manage the environmental impact of a project, the soil classification map will assist in the planning and development phase and ensure efficiency is maintained throughout the project.

Initial investigation and examination of any site is vital to assess the suitability for a designated purpose. In many cases, stability problems can occur due to weakened soil conditions under the surface, which can have serious safety implications.

Slope stability requires an extensive assessment of the soil profile, as well as the relative strength of the underlying soil structure. If a slope is deemed to be potentially hazardous for a specific purpose, then measures can be put in place to stabilise the immediate area.

Water is one of the most important factors when conducting slope stability analysis and can affect different types of soils in different ways. The presence of moisture in certain soil classifications can result in greater erosion propensity and jeopardise the substructure of a slope or embankment.

Confidence in slope stability is essential in any project. A professional assessment by qualified geotechnical engineers allows the appropriate risk assessment and subsequent measures to be put into place to ensure the safe and secure utility of a sloping surface or embankment.

Did you know soil chemistry changes fairly rapidly over time?

Biological and chemical processes break down or combine compounds within the soil mix. These processes change once the soil is removed from its natural ecosystem (flora and fauna that penetrate the sampled area) and environment (temperature, moisture, and solar light/radiation cycles).

As a result, the chemical composition analysis accuracy can be improved if the soil is analysed soon after its extraction — usually within a relative time period of 24 hours. The chemical changes in the soil can be slowed during storage and transportation by freezing it. Air drying can also preserve the soil sample for many months.

Concrete has a high compressive strength, but a much lower tensile strength, and hence is often reinforced with steel and rebar. Like all solid materials it is subject to ‘creep’, the tendency of a solid compound to move slowly or deform permanently under the influence of mechanical stresses.

Creep is also known as cold flow, and counterintuitively given that moniker, is more severe in materials that are subjected to heat for long periods, and generally increases as they near their melting point.

Developments are more frequently being constructed on soft sediment bases. This is due to both the profusion of offshore projects where water depths now mostly exceed 500m, and due to the lack of solid base available on shore for projects such as the production of new transport corridors.

Comprehensive and accurate testing of soft soil sediments are vital to ensure project time and cost budgets are not blown out once construction commences.

Time taken in the testing phase of projects is also well spent when dealing with soft soils as this is the time to develop appropriate and realistic whole-of-life performance projections and maintenance schedules.

Once detailed testing analyses have been undertaken a holistic picture of the challenges and opportunities facing the project can be made clear. This allows for the development and implementation of specific soft soil construction tactics such as using prefabricated vertical drains with surcharge, stability berms, structural geofabric, vibro-replacement stone columns, dry soil mixing, vacuum consolidation, dynamic replacement columns and lightweight bottom ash fill.