What to use? Top Soil, Compost, Potting Soil?

We see it in the local nurseries. Piles of bags of topsoil, compost, and potting soil.  All three play a very important part in the garden, but because of their different compositions, we use them for different purposes in the garden.

Topsoil

True topsoil is the uppermost portion of the ground beneath our feet. It contains organic matter that gives it the typical darker colour. Its structure makes it easier to cultivate and better able to absorb water. The higher level of biological activity, insects and microorganisms, reduces compaction and increases soil health.  The topsoil layer is where nutrients are delivered to plants, water is absorbed, sunlight helps to aid the growing process, and wildlife and microorganisms interact with the plant in various ways.

Topsoil formation is an incredibly slow process, typically taking 100 years for every inch of soil. It is formed from the weathering of rocks and the subsequent addition of organic material from decaying plants and animals. This enriches the soil and adds the nutrients essential to support plant life.

Can you buy real topsoil?  No. You will find most companies telling you they have enriched the topsoil, by adding compost to the soil.  The reason for this is when topsoil is handled and transported the structure and porosity collapses and it looses all of its beneficial characteristics.

Compost

Composting is a broad term used to explain the process of recycling organic materials. When organic materials such as food scraps, leaves, and animal products decompose properly, you end up with compost. It is a nutrient-rich material that looks like dirt and can be used to improve soil and support plant growth. Composting merely accelerates the decomposition process by creating the perfect environment for bacteria, fungus, and other insects such as worms, sowbugs, and nematodes to do their work.

Compost is the term used to describe the final decomposed material, which resembles fertile garden soil. Compost is full of nutrients and is often called “black gold” by farmers. It can be used for gardening, horticulture, and farming.

Potting soil / Potting mix

Potting soil / Potting Mix is not soil at all, but a blend of materials like composted bark, perlite, peat moss, vermiculite, and compost. Potting soil / Potting mix is designed to retain nutrients and moisture.  Potting mix/soil keeps the containers from becoming too compact, which can suffocate roots and slow the flow of water and nutrients.

It is fairly easy to create a potting mix at home

• 1 bucket coco peat
• ½ bucket perlite
• ½ bucket fine compost
• ½ bucket vermiculite
• 2 cups of river sand
• 2 cups of slow-release fertiliser (Talborne) 

Potting soil/mix is better if you need a growing medium for container plants

Today’s soil is not that rich dark soil that we saw in our grandparents backyard.  Using unsustainable practices in back gardens, the soil has been depleted, making topsoil not as nutrient rich.

If you are preparing a new piece of ground for planting a vegetable garden, it’s important to start with good soil that is high in nutrients and will feed your plants as they grow. The easy way to accomplish this is to simply buy prepared topsoil, then add it to your site before planting, mix it into the existing soil, and begin planting.  This will not be true topsoil but will have compost in the mix to give the soil a good nutrient boost.

In time you can start creating topsoil.  By not tilling your soil, chop and drop, and adding compost as a mulch on your beds and around your plants, you will create topsoil that is dark brown / black in colour and porous so it can hold lots of moisture and air.   This layer is also where many insects, fungus and bacteria will live.

Start implementing more sustainable practices within your garden, and before you know it, you will have an active microbial environment thriving in your soil.

Happy Soil Building Friends

Tash and Family