In my time living in this region of Victoria, I have noticed a trend in soil quality. Such qualities of the soil here include high clay content (made up of very fine particulate rock), high sodicity, and high fertility. In the area I live, the soil that makes up the land is known as red sodosoil. When dry, sodosil is very hard. When broken down, it is very fine and be easily blown by the wind. When water is applied to the soil (when dry), the soil absorbs the water and in turn becomes a thick paste which can get everywhere. Enough water absorbed by red sodosoil can clump into clods and be very difficult to handle. In summer, moist soil dry out and start to crack, and becomes very hard.
The WVVP is found over a weak section of the Indo-Australian Plate. Due to this weakness, magma can easily deform the area, and penetrate to the surface of the crust. Many inactive volcanoes dot this area, and past irruption brings high levels of nutrients into the soil through basaltic rock. When the basaltic rock breaks down, it forms a very fine particulate that forms a portion of the clay soil. Clay soil can be found in some locations with organic material, but in my experience exposed clay soil hardly ever contains broken down organic matter further than a few inches.
The soil quality changes dramatically when found near the area of the proto-Werribee River. When the sea level was much higher than it is today, thousands of years ago, the opening to the Werribee River was a delta. Most sedimentary rock that was carried by the river were deposited around this area, and today make up a sandy loam that is highly significant to farmers.
A general overall agreement I have found is that no matter where the soil is located in this area, it contains a high level of nutrients. Many weeds that can tolerate the heavy, poorly draining soil actually do thrive and grow very well. Adding organic material and mulching well without breaking the soil up gradually improves the overall tilth of the soil and is surprisingly workable.
The quality of the soil found away from the Werribee Delta, as stated, is high in clay content, and as a result has a large significance to the environment found in this area. A high percentage of the environment found in this area are plains grasslands; Flat, rolling hills with a low percentage of shrubs or trees. Grasses proliferate due to being great rooting plants that can tolerate dry conditions and reproduce very quickly. The plains grasslands are found most commonly in both the Victorian Volcanic Plains and Riverina bioregions, the former being greatly impacted by the booming suburban population and is currently classified as critically endangered.
