WHEN SOILS JUST AIN’T SOILS

IT’S THE FOUNDATION FOR ANY FLOURISHING GARDEN AND THIS WEEK WE TAKE A DEEP DIVE TO FIND OUT HOW TO ENSURE YOUR SOIL IS HEALTHY

IS your soil good enough to put on your face?

Cleopatra imported nutrient-rich soil for her mud mask.

Soil that is rich in minerals has the power to detoxify the body as well as grow healthy food full of many minerals.

Plants use sunlight, water and carbon dioxide in a process called photosynthesis to create sugars (energy), which they store in their leaves and are readily available to us when we consume the leaves, seeds and fruits of the plant.

In addition there are many mineral nutrients contained in plant foods and these are obtained by the plant through their root system.

The roots of plants have many functions; they attach the plant to the ground for stability, draw up water for hydration, transport and store minerals for the plant’s use and have a symbiotic relationship with micro organisms and fungi.

Terrestrial plants depend on soil to provide all the nutrients they require. Plants have evolved many pathways by which they extract and transport water and nutrients through their root system. The type of soil will determine plant growth and subsequently the species of plants that the soil can support.

Clay soils become waterlogged in the wet season yet do not hold water in the dry season. Clay soils, although high in nutrients, lack carbon, (organic matter).

Sandy soils are low in nutrients, will not hold water and do not provide a stable medium to support large plants.

Silt soils are slippery, they contain small particles which hold water but when they are dry are difficult to rehydrate. Silty soils are low in organic matter.

Old volcanic soils, as found in areas in the Wet Tropics region, were very fertile but have been depleted through weathering following the removal of rainforest for intensive farming.

Loamy soils are a mixture of sand, silt and clay – if they are in equal preparations they provide all the requirements for most plants to grow.

Our soils are a valuable commodity and the basic building block for life on Earth. Without them nothing grows. Once cleared of vegetation soils can blow away in the wind or wash away in rain events.

It’s not only farmers who need to prevent soil disappearing off their productive paddocks, it’s every gardener, especially gardeners who are attempting to be self-sufficient on their own block of land.

Scientists have calculated that in wet tropical areas, such as Far North Queensland, it takes 200 years to naturally form one centimetre of soil. However, if we fail to mulch the soil and construct low spoon drains to slow down water run-off, we can lose a centimetre of soil in one rain event.

The top one centimetre of soil is not just any old soil, it’s topsoil, and topsoil is precious. Soil scientists have found that topsoil consists of fungi, bacteria, micro organisms, worms and beetles such as coleoptere. They calculate that it takes 3000 years for the top one centimetre layer of soil (the topsoil) to naturally accumulate enough substances to make this soil fertile.

So how can we keep topsoil on the garden when we have changed the renewable cycle of the land?

In the rainforest the soil is protected from heavy rain drops by tree canopies. In addition, leaves from these trees constantly fall, layering the soil and breaking the force of the rain that penetrates the forest canopy.

The layer of leaves is the food source for the millions of micro organisms, bacteria, fungi and other creatures that set in process the mechanism of recycling the leafy bounty of nutrients which in time becomes the fertile layer of topsoil.

To improve the fertility of the backyard garden it is important to plant a green manure crop which is turned into the soil when it flowers. The chemicals released into the soil when green waste is broken down promotes micro organisms to flourish. The green legume returns nitrogen to the soil resulting in an increase in soil fertility.

If you cannot grow a green manure crop then ‘trash blanket’ the garden with compost and mulch. Worms will start the process of taking the organic matter into soil where it will provide plants with the nutrients they need to grow healthy roots to extract even more nutrients from the soil. For every kilo of flower, fruit or vegetables you take from the soil, put two kilos back in the way of compost and mulch. Become a ‘soil farmer’ and your crops will flourish.