topsoil lawn

Soil Profile showing showing the topsoil layer.

Melbourne Topsoil – 9 Great Money saving tips.

Topsoil in Melbourne

Topsoil in Melbourne is heavily dependent on the underlying geological material, if there has not been a history of topsoil ameliorations or importation of topsoil from other locations. According to the Department of Agriculture, topsoils of Melbourne can be divided into 9 distinct types. In some parts of Melbourne, the importation of topsoil will be a bigger factor than the geographic and climatic range. Knowing the type of your natural topsoil can help you save money when deciding on what topsoil amelioration is required. Some Melbourne clay topsoils will benefit greatly with the addition of gypsum, but for others the only benefit of gypsum will be the addition of calcium to the soil.

Sporting grounds, in particular, will normally have a thick layer of imported friable topsoil so if your garden is built on one of the closed Melbourne racetracks like Richmond, Cheltenham or Braeside your topsoil could be different to your neighbour across the street.

 

What is Topsoil?

 

Topsoil is the layer of soil just below the surface layers. The surface layers are the layers containing the litter of plant residues as well as accumulated organic matter with some mineral soil and most of the soil life.

Typical Garden Topsoil

Typical Garden Topsoil

 

Nine types of Melbourne Topsoil

 

1.    Red Loam Topsoil

This could be the best natural topsoil in the whole of Melbourne as they are well structured deep and friable. These topsoils can be mildly acidic like most topsoils in hilly wooded ranges. They can be a little poor in plant nutrients, so regular amelioration with organic matter will be of great benefit to the soil. On lawn areas a light annual application of garden lime will help. Farmers know that red earth is great for farming.

The red loam topsoil will mostly be found to the East of Melbourne in the upper Dandenong ranges and in the hills between Monbulk and Silvan. This type of topsoil will normally suit a wide range of plants as is has excellent drainage, and a good soil structure for plant root development.

Red sandy Loam topsoil.

Red sandy Loam topsoil.

2.    Brown Loam topsoil over Clay

These topsoils formed over the older basalts on the southern Mornington Peninsula. This is the brown-grey loamy friable topsoil naturally occurring in places between Main Ridge and Flinders. For best results in your garden, ameliorate with manure and organic matter. Take care not to cultivate too deep and bring the clay to the surface.

Brown Sandy Loam Topsoil

Brown Sandy Loam Topsoil similar in Colour and texture to Main Ridge Topsoils on the Mornington Peninsula .

3.    Dark grey sand topsoil over clay

These topsoils are found over a large part of Melbourne. The flat and undulating land between Kew and Mount Waverley as well as deeper topsoils in Tyabb, Balnarring Frankston and Mornington. This topsoil is also over a huge part of the Melbourne suburbs within a triangle from Dandenong to Cheltenham and over to Toorak. After long periods of heavy rainfall, a watertable may occur over the clays. It is important for Melbourne Landscapers to take drainage into account when landscaping on these soils. As with other Melbourne loam over clay soils, ameliorate with manure and organic matter. Take care not to cultivate too deep and bring the clay to the surface.

 

4.    Light Grey loams over clay

A light grey loam with some gravel and small stones found in the suburbs to the North East of Melbourne. These soils will be found around a strip from Rowville to Bundoora and from Croydon to Kew. At the boundary of the topsoil and clay layers large angular stones occur which makes digging drainage difficult for residential landscapers. Generally, these soils are deficient in humus and nutrients. Melbourne landscapers should dig in organic matter and manures to ameliorate these soils. As the clays here are generally reactive, an application of gypsum can help drainage and soil structure. A small amount of garden lime can be added to correct acidity.

 

5.    Gritty light grey loam over clay.

Topsoils formed over parent granite at Mount Martha and Arthurs Seat on the Mornington Peninsula as well as Hallam, Lysterfield and a few other places. The sandy loam is generally ok for drainage but has poor water holding capacity. The abrupt transition between the sandy loam and the mottled yellow brown and grey clay can lead to water logging on lower slopes in winter and spring.

If this is the case, landscapers should consider subsoil drainage systems. As the soil has poor water holding capacity, landscapers should dig in plenty of organic matter as well as install an irrigation system with a dripper. Generally, this soils are only mildly acidic.

6.    Dark Loams Local Sands and Clays

The parts of Melbourne which were previously swampy or flood plains like the Melbourne Suburbs close to the Yarra. These Melbourne suburbs include Banksia Park near Heidelberg and Bulleen. The frequently flooded Yarra floodplain of the lower-middle yarra river and tributaries were once covered in Manna gum, swamp gum and river red gum with swamp paperbark in the wettest areas. These are a mix of topsoils and it can be difficult to draw conclusions on drainage. Landscapers should ameliorate with manure and organic matter.

 

7.    Deep Sands free of Lime

This is the natural topsoil in coastal gardens between Black Rock and Brighton and along the coast of Port Phillip Bay all the way to Rye. Some of the land previously used for market gardens in Langwarrin and Cranbourne have this soil. These soils are generally very deficient in nutrients, so landscapers should dig in plenty of manure and organic matter to improve the soil. Annual applications of garden lime will help to neutralize the acidity.

 

8.    Deep Sands with Lime

The topsoil between Sorrento and Cape Schank in the coastal sand dune areas is a whitish grey sand occasionally over a hard lime base. These soils can be either acidic or alkaline, so if your plants are not thriving a soil PH test may be required. Landscapers should dig in plenty of manure and organic matter as well as install an irrigation dripper system. The coastal plant selection for these soils needs to be particularly salt, wind and lime tolerant.

 

9.    Heavy clay topsoil over basalts

The suburbs to the west and north-west of Melbourne are well known for their heavy clay soils. This area stretches all the way from Richmond to Broadmeadows and Altona to Thomastown. These soils are characterized by a thin loamy topsoil over dark reddish-brown heavy clays. Often outcrops of the basalt can been seen on the ground surface. The soil structure can be improved with the addition of gypsum and landscapers should dig in plenty of organic matter. For lawns and other gardens sandy loam soil will need to be imported. For the home landscaper, the digging of the requires drainage trenches can be difficult.

 

 

Landscaping poor draining topsoil

For your backyard or frontward lawn, the ground can be sloped a bit more to aid with drainage. Depending on the usage and the makeup of the layers below, you could probably get away with as little as 100 to 150mm of topsoil for your garden lawn. For example green couch Cynodon dactylon, the roots will penetrate the ground up to 1.5 metres deep with much of the root mass at around 600mm deep. For this reason the layer below the top soil needs to be suitable for root growth if you want your lawn to be drought tolerant.

 

Will gypsum help?

 

Clay soils

 

Gypsum is the most widely used calcium additive for garden. If you need gypsum, you can save money by buying it in bulk from your landscape supplier. If the subsoil has a hard clay layer the moisture and the roots might not penetrate or your lawn and you could have poor drainage. Some clays will respond to the addition of gypsum. This will be the case if the clay you have is a flocculant clay. Clays like montmorillonite with high levels of exchangeable sodium will generally be improved by digging in some gypsum. You can perform a simple soil test your clay by putting it in a jar with some pure water, then stirring to create colloidal mix. The mix will appear cloudy.You then add some Epsom salts or gypsum to the mix and watch what happens. If the clay then forms flocculant, or larger, particles that sink to the bottom of the jar leaving a clear layer of water, then your clay is flocculant. Individual clay particles are made up of fine flakes smaller than 0.004 mm. Depending on the type of clay, the fine particles are held tightly together by either weak bonds in the case of kaolinite or stronger bonds if the clay contains positively charged metal ions such as sodium, calcium or potassium. The negatively charged clay particles will repel each other but the individual flakes will bond to each other.

 

Negatively charged clay particles repel each other.

Negatively charged clay particles repel each other.

 

 

In the heavy flocculant clay topsoils of Melbourne’s western suburbs, gypsum can help to displace sodium and improve the soil structure.

 

Saline soils

 

If your garden is near Cape Schank or Sorrento, or if you have a windswept coastal garden, then you might have some soil salinity to contend with. This could also be the case if you are by the sea in Biggera Waters, Runaway Bay or Hollywell and get sea water spray on your lawns and gardens. With saline soil, gypsum will also help as the calcium in the gypsum will remove sodium from the soil.

 

The disadvantages of gypsum

After an application of gypsum, you should follow up later with slow release fertiliser like Neutrog. Upsurge. Nutrients such as Iron and Manganese can be leached from the soil by the addition of gypsum. Applying excessive gypsum to sandy soils can result in the plants transportation system for zinc, copper and phosphorus being affected.

 

Agricultural lime

Agricultural lime may be a combination of calcium and magnesium carbonates if it is made from dolomitic rather than calcitic limestone deposits. Use on acidic soils to increase the PH.

 

Soil Testing

Soil testing kits can be used for simple PH checks of your garden soils. If your plants are not thriving despite all of the care and attention, then samples of your soil can be taken to a laboratory for analysis.

Soils can be tested in a laboratory for salinity or contamination.

Soils can be tested in a laboratory for salinity or contamination.

Buying Landscaping soils

When buying landscaping topsoil, always check that you are buying a high-quality product that meets the Australian Standard for topsoil. Soil should also be free of weeds and other contaminants. For lawns, your topsoil needs to be very free draining. The best soil for top dressing lawns is a very sandy soil. For garden beds a little bit of the natural clay soil mixed in will help water retention.

The soil is an indispensable ingredient for the life of humans, animals and ,of course, plants. The soil supplies nutrients and raw materials, storage and filtered water. The soil can degrade harmful chemicals but healthy soil should not be taken for granted. If we allow our soil to be overused, or allow a hard crust to form, then the soil will require amendments to replenish the nutrient store and to make the soil friable. Water will tend to run-off taking some of the soil and nutrients with it.

A healthy soil will contain a great deal of life. Not just microorganisms like bacteria and fungus, but also earthworms. Many of these will form a symbiotic relationship with your plants.

In Melbourne we a lucky enough to have some great resources to improve and maintain the health of your soil. First of all, you should be using a layer of mulch. Mulches such as pea straw and sugar cane mulch will decompose relatively quickly and bring your soil to life. This is especially true when used with an organic fertiliser. If you are after a different look to the sugar cane mulch, you can always use a different mulch over the top. Take care not to mulch up to the truck of trees or shrubs, as this can lead to collar rot. If using a mulch like pea straw, make sure it is weed free. Secondly, consider using a soil tonic to improve your topsoil.

 

Commercial Landscaping Topsoils

For commercial landscaping the topsoil needs to be high quality soils to the Australian Standard.  AS 4419-2003 is the standard for soils for landscaping and garden use and specifies requirements for general purpose soils, top dressing soils, topsoils and landscaping mixes for both domestic and commercial use. The standard also provides guidance on the use and selection of soils. For example low density soil, which is often used in commercial landscaping for large landscape containers and rooftop gardens.

One very important requirement for topsoil for the commercial landscaping of public spaces is the soil cleanliness. Soils use must be free of all hazards and contaminants and also free from any weeds.

 

 

© 2020 Reds Landscaping and Civil – Melbourne Landscaper.

 

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5 Steps for a Great Melbourne Lawn

Lawn renovation is best done in early Autumn in Melbourne gardens. Take the  time to assess your lawn and plan for some renovation and repair work. Start by walking over your lawn and checking for any bald patches, or high spots or dips.

Lawn Irrigation Systems

Turn on your irrigation system and check if all parts of the lawn are getting adequate water. If you cannot push the tines of a fork into the bald patches, then the soil might be compressed or the irrigation is not reaching that spot. Also check for weeds and other pests and diseases whilst you are there.

What is the best treatment for grass?

Step 1 – Lawn Weed removal

The first step in a successful lawn renovation is to remove the weeds. If the weather is sunny, you could use a selective spray, but do not be afraid of digging the weeds out by hand.

lawn care melbourne Removing weeds

Lawn care Melbourne. Broadleaf weeds can be removed by hand or with a selective spray.

Step 2 – Aeration of the Lawn

To make this job easier, give the grass a really good soaking or do it just after a good rain. Using a granulated or spray on soil wetter will help too. The slugs of soil should come up the aerator tines and drop out onto your lawn.

Mechanical Lawn Aerator for large or commercial lawns

Mechanical Lawn Aerator for large or commercial lawns. Aeration is an essential part of lawn repair.

 

If you have a smaller area of lawn, then Bunnings have a hand held aerator that is reasonably priced. You can get a  cyclone aerator at around $55 – $60. This is money well spent.

Hand Held Aerator. Great for renovation work.

Hand Held Aerator. Great for renovation work.

The holes made by the aerator, will allow oxygen, water and nutrients to quickly get to the roots. This is especially important if you have some high traffic areas that may have had some compression and wear.

 

Lawn topsoil profile shows the effect of aeration.

Lawn topsoil profile shows the effectiveness of aeration in getting oxygen and nutrients to the lawn roots.

Step 3 – Over sow grass seeds.

If you have hybrid roll out grass then you will not find grass seeds of the exact same type of grass. Your local plant nursery will be able to suggest something that looks similar. Sowing Lawn seeds in early Autumn, means that the new lawn grasses have all winter and spring to get established before the next hot summer.

Oversow lawn

Oversow the lawn with new lawn-seed. Ensure seeds go into the aeration holes.

 

Step 4 – Top dress the lawn.

Top dress  with either a high quality sandy loam with a little organic matter, or a course sand. The course sand works well in high traffic areas, but a topsoil high in organic matter is better at holding  moisture. For real problem areas, try top dressing with a cheap fine textured potting mix. When topdressing, take care to fill any low points and bring the level up evenly to any paths or edges. Protruding pavers can make a real mess of your mower blades if the lawn is lower than your pavers. Depending on the type of topsoil you have you may want to top dress with some gypsum to break up the clay.  The gypsum will penetrate deep into the lawn through the aeration holes.

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Topdressing with cheap potting mix

For small bald patches in your lawn, a cheap fine potting mix can be a good alternative to sandy loam. The whole nature strip below has been repaired this way, and the rapid growth in the grass is amazing.  The potting mix helps to keep the grass seeds moist for germination and can give some protection from birds.

top dressing with a cheap fine textured potting mix

Top dressing with a cheap fine textured potting mix. This is a great solution for small problem areas or bald patches in your lawn.

 

Step 5 – Apply Soil Wetter and Liquid Fertiliser to your lawn.

Give your grass a liquid fertiliser like Neutrog Seamungus as well as some more soil wetter. The liquid fertiliser will encourage plant and root growth. The soil wetter is required as often the top dress soils are hydrophobic, resulting in the water just running off the soil. If you repeat this last step for 3 or 4 weeks the results will be amazing.

hydrophobic-hydrophilic

Hydrophobic versus hydrophilic. A surfactant will help if your lawn topsoil has become hydrophobic and is repelling water. In hydrophobic soils water will tend to run off and not find its way to the lawn roots. Aerating and some garden lime will help as well.

 

The Lawn Topsoil Conundrum.

For hard wearing lawn the topsoil needs to be a sandy loam. This type of soil should also be used when topdressing the high traffic areas of your lawn. This will also mean that the area will require regular watering or an irrigation system to stay green as the soil moisture content will be lower in these areas. One solution to this problem is to use a product like Neutrog Seamungus after aerating to help the soil retain moisture. We have had some success using this product on some of our commercial landscaping lawns.

Soil moisture

The ability of your soil to provide moisture will depend on the soil structure and the amount of organic matter.

Restoring Commercial Landscaping Lawns

When restoring commercial landscaping grassed areas many of the same principles apply as they would to a very large residential area.

The use of mechanical spreaders and mechanical aerators is required to do economical  restoration to a large area. Many lawns in public spaces need to be very hard wearing, so sandy loam topsoils and irrigation systems using harvested rainwater are often used. Often there is a trade-off between green attractive grass and sustainability with areas browning off a little over summer. Couch grass will often brown in the colder months, but this is not a major concern either.

commercial landscaping lawn

Commercial landscaping grass just starting to green up after the application of soil wetters and Neutrog Seamungus.

 

Many commercial landscapes will use a hard wearing kikuyu in either an instant roll out or using hydroseeding or hydromulching. 

Related Landscaping Ideas from Red’s Landscaping

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Screening Plants for Garden Privacy

 

New Home Construction Landscaping

 

5 Melbourne Garden Weeds and how to prevent them.

3 Best Types of Concrete Retaining Wall

 

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