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Let's get down to earth

Owen Pidgeon

Compost, Worm, Soil, Gardening,  Earthworm, Nature, Environmental Conservation, Environment, Healthy Lifestyle, Growth, Green Living, New Life,
Compost, Worm, Soil, Gardening, Earthworm, Nature, Environmental Conservation, Environment, Healthy Lifestyle, Growth, Green Living, New Life,Supplied

Healthy soil is essential for healthy plant growth. At this time of the year, just before the growing season really begins, improving your soil is very worthwhile.

The aim is to help plants develop strong, deep root systems. By enhancing your soil structure, the little roots can spread more easily and develop those many little fibrous roots that are so vital for absorbing nutrients. Plants need to access 16 essential nutrients.

The balance of moisture in the soil is also critical. You need enough moisture to stimulate the beneficial soil microbes that convert nutrients into plant-accessible forms. Plants also need to be able to continually draw in moisture. Without water, the root systems will be poor. Waterlogging is also a problem.

Where you have rocks in the soil, remove them. Plants are adventurous and they will try to grow through rocky soils but it will set back their development. The other day we were transplanting a small apricot tree that had been growing in a rubble bed and we discovered one root had grown through one of the three holes in a house brick. We broke off the remaining brick to see a fat root structure with a 10-centimetre-long pipe section.

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There are a lot of poor shale soils and densely packed clays - often with shallow top soils - in the Canberra region. Property developers are to blame for much of this, as they have stripped the top soils before levelling the ground. Clay subsoils are usually low in plant nutrients but if well structured they can compensate by being good at storing moisture. Too much clay or a compacted soil will prevent water penetrating and hinder aeration.

You can greatly improve soil texture by adding a few simple but essential elements. Apply gypsum at a rate of one kilogram a square metre and dig it into your garden beds of clay soils. Gypsum will aggregate clay particles and reduce high sodium content. Mixing in river sand will lighten the soil texture but you need a trailer load for a large garden area. Where the pH levels are very low (an acidic soil) dig in lime, which also helps aggregate the clay particles.

You want a good amount of organic matter throughout the garden. Add compost and other organic matter regularly to improve the tilth of the soil, add nutrients, help water retention and provide food and shelter for the micro soil organisms.

For the plants to access organic matter, you need a microbially active soil. There can be millions of microbes in a small garden bed if the conditions are right. They are the worker bees of the soil, breaking down raw organic matter, helping to access mineral elements and convert essential plant nutrients into the form that plants can access.

The plants' roots release signals to nearby soil microbes about minerals the plant needs.

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The importance of soil microbes is one of the reasons for avoiding harmful chemicals. Microbes work to bind clay particles to humus particles to form the wonderful clay-humus crumb. This crumb contributes to good soil structure with excellent ability to hold water.

Earthworms are also vital and should be encouraged to multiply in any garden. A good layer of mulch and good moisture levels are critical for earthworms. They help with breaking up heavy soils, allowing water and air to penetrate. They will also shred and bury organic matter and bring essential elements from deeper down. They secrete mucus that binds soil particles together and provides growth-stimulating nutrients to plants. And they leave behind those wonderful castings that add to the soil's organic content.

This week

■ Welcome all frosty mornings in August. They usually herald a fine day with only light winds to get back into the garden. Heavy frosts are the best natural control of fruit fly and the run of cold nights provides sufficient chill hours needed for good pome fruit setting;

■ Plant out spinach and onion seedlings. Plant rows of snap peas and snowpeas. Complete planting out asparagus and rhubarb into richly prepared, deep garden beds;

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■ Turn older compost heaps to aerate and speed-up the process of decomposition;

■ Fertilise citrus trees with a nitrogen-rich fertiliser or relatively fresh chicken manure around the perimeter of the tree - the dripline.

Owen Pidgeon runs the Loriendale Organic Orchard, near Hall.

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