How to create a compost or trench bed for vegetables

A trench bed is like a compost bin, dug into the ground and consisting of alternate layers of fresh green ‘live’ organic material, brown ‘dead’ organic material, fresh manure and soil. Note that each layer of dead or live organic matter is covered with soil & watered before another layer is added.

Trench beds are worth considering if you have extremely poor soil of if you live in a dry climate. The result is better water retention, good soil aeration and an on-going supply of nutrients for micro-organisms and plants. It’s important to keep feeding the soil organically thereafter for long term success.

MATERIALS NEEDED

Gather a spade, water (hosepipe or buckets), live organic matter in bags/piles: green garden and kitchen waste, moist seaweed, horse or cow manure or any other fresh untreated organic matter, dead organic material in bags/piles: newspaper, sticks, dead leaves & cuttings and any other dried out organic material. Compost is optional if you want to plant soon. You will also need four 1/2 metre long sticks (to be used as markers).

PREPARATION

Measure out your trench (however long you like but no wider than a metre (for easy reach). Dig out 30cm of top soil (pile it besides the trench, remove stones).

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Dig another 30cm of sub-soil (create a separate pile and remove any stones).
Loosen the base of the trench with a garden fork.

Cover the base and sides of the trench with cardboard or newspaper. Moisten with some water.

Lay sticks on the bottom (or other rough material) up to a height of 20cm.

Place 10cm of your subsoil over the sticks. Give a light shower of water.

Place 10cm of dry/dead organic material over the subsoil. Water lightly again.

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Lay 10cm of green/colourful live material over the brown material (I included rinsed seaweed), cover with a layer of soil and water.

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Place bits of horse or cow manure over the green layer and water, add some soil & water.

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Repeat the layering process until your trench is full (leave out the stick step).

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COMPLETION

Place 1/2 metre long sticks at each corner of the trench to use as markers.

Place the topsoil you dug out earlier over the top. The bed will now stand about 20cm higher than the ground but will drop with time. Add compost (one bucket of compost per m2), level out & water well.

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Place a mulch of your choice onto the ‘skin’ of the soil to protect it.

The bed is ready to be planted (wait for a month if you prefer to leave out the composting step). Just add a little patience and before long, you’ll be so glad you put in the effort.

MAINTENANCE

Once your plants have taken, feed them with a liquid natural home-made fertiliser every week or so and compost every now and again. Avoid walking on the bed to keep it soft and aerated.

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Vegetable gardening: how to prepare a trench bed

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It may have taken what felt like a day to dig and prepare our first trench bed (45cm depth x 3m length x 0.5m width) but what it did was get me in touch: I now know the intimate details of the soil’s make-up and where the sunny spots are in the courtyard at various times of the day. Best of all, there’s no doubt that our vegetables and herbs are going to have a nutritious and balanced diet.

I attended the Soil for Life course recently, so it’s thanks to Pat Featherstone (our inspired teacher who also wrote the manual) and Livingstone (who got us involved in the practical side) that I can confidently share the following information.

What is a trench bed?

You could think of a trench bed as a compost bin that’s dug into the ground. The bed is made up of alternate layers of fresh green organic material, dead organic material, manure and soil. This organic base is pretty much a dream diet in the making for your future plantings of vegetables or other plants.

Why a trench bed?

Trench beds are a good way to go if you’re living in a dry area or if you have poor or average soil. The bed allows for excellent aeration, water retention and a long-term supply of nutrients for your plants. It requires some muscle power to begin with… but you won’t look back once you’ve started!

What you’ll need

A spade, fork, water, newspaper, sticks, dead and alive organic matter, manure and mulch. You will also need compost if you want to plant sooner rather than later.

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Divide your organic waste into ‘live waste’ (green garden and kitchen waste, moist seaweed, horse or cow manure, any fresh untreated organic matter) and ‘dead waste’ (any of the former, but dried out).

PREPARATION

Meaure out your trench. It can be as long as you like but shouldn’t be wider than a metre (to allow for easy reach).

Dig out the first 30cm of top soil (pile the soil next to your trench and remove any stones).

Dig out the the next 30cm of sub-soil (place it in a seperate pile and remove any stones).

Use a garden fork to loosen up the base of the trench.

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Cover the bottom and sides of the trench with NEWSPAPER (or cardboard). Moisten the paper with a sprinkling of water. (I skipped this step because the base of this trench is like solid rock and it is the rainy season so no need to use paper to retain extra water).

LAYER THE ORGANIC MATTER

Lay STICKS (or other course material) over the base of the trench — aim for a height of 20cm.

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Lay 10cm of SUBSOIL over the sticks and water.

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Lay 10cm of DRY BROWN material over the subsoil and water well.

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Lay 10cm of WET GREEN material over the dead, dry brown material and water.

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Sprinkle horse or cow MANURE over the top and water.

Repeat this layering process (leaving out the sticks and newspaper at this point)… until the trench is full.

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FINAL STEPS

Insert 1/2 metre long marker sticks into each corner of the bed.

Lay the TOPSOIL over the last layer. The surface will be about 20cm higher than the surrounding ground at this stage. It will drop over time.

Cover the topsoil with a MULCH of your choice (eg. straw or leaves) to protect the area from the elements. (I used seaweed but beware of sand fleas!!)

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Let the bed rest for a month before planting. Alternatively you can speed up the process by working COMPOST into the topsoil before mulching. Use a bucket of compost per square metre, level the area out, water well and begin planting.

PS. Avoid walking on the bed! Also, even though you have given your plants a great start, keep feeding them with a weekly liquid natural home-made fertiliser… and keep composting every now and again.