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Why garden material should stay there

It’s the cheapest and most sustainable method of providing raw material for soil life, argues gardener

Grant Douglas. Grant Douglas is a lifelong self-taught gardener, based in Motueka, Tasman.

Ihave a relatively new garden, coming up to four years. Although it is young, it produces a large amount of material, especially of the soft herbaceous kind that comes from tall and medium perennials such as salvias, dahlias, and phlox.

In the past four years, I have not made large quantities of compost, nor taken trailer-loads of material off the property.

Instead, I’ve returned all material, mostly back to where it was harvested from.

This is the cheapest and most sustainable method of providing raw material for the soil life.

Only fine material, such as chickweed, grasses and nonworm-farm-compatible material go into the compost bin.

Just as eating healthy food can give us a healthier body, so with plants a healthy soil can help them flourish. When we think of plant nutrition, we should think of feeding the soil.

Much of the nutrients in the soil are produced during decomposition of organic material by the micro-organisms made up of bacteria and fungi (one teaspoon of healthy soil can contain from 100 million to 15 billion organisms) and other life forms, such as insects, nematodes and earthworms.

The raw material for the soil life to produce nutrients and improve soil structure is organic material. Growers employ a number of ways of maintaining the organic matter on or in the soil, varying greatly in cost, labour and imported materials.

One of the most common ways is the composting of material from the garden, or imported from outside. To ‘‘hot’’ compost, material must be gathered together in the right proportions and layered in the correct way to generate sufficient heat to kill

weed seeds and diseases. This is the biggest advantage of hot composting.

The result of hot composting is a material high in nutrients but low in raw organic matter. It has all been broken down to humus, so there is very little left for the soil life to feed on.

Hot composting can also be a very labour-intensive and potentially expensive exercise, especially if material is needed to be imported.

The alternative composting method is slow composting: building up layers as material becomes available, which produces ‘‘cold’’ compost (no killing of seed or disease), resulting in partial decomposition and thus providing more raw material for the soil life.

The shredder I use has a tumbler, rather than a horizontal blade, which deals with lighter material without getting blocked too often. The shredder cuts the

material into manageable lengths for applying to the garden.

Using a mulcher is a more sophisticated method of the old ‘‘cut and drop’’ method – cutting any plant material into smallish pieces immediately where it is harvested from.

The one exception to this method is in the vegetable garden, because of the possibility of transferring disease from one year to the next.

The other major ‘‘in house’’ source of material is the muchmaligned lawn. A lawn does not need to be a monoculture but can contain clover, which helps fix nitrogen and thus complements the nutrition for the other plants. It can also contain a variety of herbs, such as camomile or penny royal.

The regular harvesting and application of one or two centimetres (never put on heavy dressings) can go a long way towards feeding the soil life.

Unfortunately, the application of hormonal broad-leaf sprays on lawns makes the clippings unusable. If the sprayed material is applied, the long-lived residue from them can cause major damage to many susceptible vegetable and ornamental plants.

This is also true of horse manure (even composted) that has come from animals that have been grazed on pasture sprayed with broad-leafed herbicides.

In the vege area, the growing, mowing and turning under or covering with plastic or weed mat of cover crops is very beneficial to soil life.

Trenching of food scraps is also an easy way of introducing raw, organic material to the soil, as are leaves. All these methods require very little outside inputs – they are self-sustainable.

The application of raw materials to the soil surface not only feeds the soil life but can also act as a weed suppressant and offer moisture retention.

Using these methods can be extended to imported material such as manures, straw, cardboard, wool and even fine bark (but because of its high carbon content, a fine dressing of blood and bone under it is beneficial). Any non-toxic, organic material can only help improve your soil.

To sum it up – material from your garden should be returned to your garden.

The easiest, cheapest, most sustainable option in most cases is to return it in the form of raw mulch, which will feed the soil life to improve your soil’s structure and nutrient levels, ultimately leading to healthier plants.

Some of the world’s most lush jungles grow on some of the world’s poorest soils but because they rapidly recycle their own material, they thrive. We should do the same in our gardens.

Homed

en-nz

2023-06-08T07:00:00.0000000Z

2023-06-08T07:00:00.0000000Z

https://fairfaxmedia.pressreader.com/article/281809993293097

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