Grow Your Own: soil matters

In every gardening handbook – whether it’s by tried and trusted gardening stalwarts like Adam the Gardener (now there’s a cartoon character who knows his onions!) to today’s celebrity veggie gardeners like Bob Flowerdew – the thing they tell you to do first is to test your soil. There are lots of websites that can tell you how to do this without forking out for a pricey soil type and pH test kit, but here’s a quick overview:

- Wet the soil, pick up a bit and squeeze it.

- If it’s silky and a bit slimy and looks like a pot before firing it’s a clay soil and needs lots of humus (by adding well-rotted organic compost) and possibly a bit of gravel to improve drainage.

- If it’s gritty and falls apart like the top of my apple crumbles, it’s a sandy soil and needs a lot of humus to add nutrients.

- If it feels spongy, it’s a peat soil. It could probably do with a bit of humus too.

- If it retains its shape without forming a rigid mass, then it’s a loam soil (lucky you!) – but it will appreciate humus to keep it sweet.

Once you know the soil type, you need to know its acidity. As a rule of thumb, if you live in a hard water area, your soil will be alkaline. If you live in a soft water area, it will be acidic. You can tell the acidity of your soil by the weeds that grow there – ours is rife with dock and nettle and the dreaded creeping buttercup – so it’s acid.

Different plants like different sorts of soil – but almost all the plants that you would want to eat will need a pH of 5 to 8. Our soil is about 4.9. While you could spread lime to try and alter the pH of your soil, it’s pretty expensive and the results are temporary. If, like us, you have such an acidic soil that your veggies struggle to thrive, either go for acid loving berries – more on them next week – or use raised beds to give you an extra depth of soil to lavish with TLC so that it becomes the perfect growing space for wonderful veggies.

But soil is so much more than a number or a label.

Soil is the source of all life. It provides nutrients that sustain all plant and animal life – including us. It absorbs and purifies our drinking water and regulates excessive rainfall. Soil helps to prevent floods. It is both a teaming mass of biodiversity and the largest carbon sink on land. It stores over three times more carbon than forests and other greenery.

Soil rocks.

But just as we are threatened with Peak Oil, so we are facing the threat of Peak Soil.

Left to its own devices, nature builds an inch of topsoil every 500 years or so. You need about 6 inches of topsoil to grow really good crops – that’s 3000 years for a decent carrot. Soil erosion has always occurred naturally, but sometime during the 19th century, the rate of topsoil loss from erosion due to agriculture exceeded the rate of soil formation. Today the situation is critical: for every pound of food eaten, the US loses 6 pounds of topsoil, the developing world loses 12 pounds and in China, they lose a staggering 18 pounds of topsoil. That’s not just unsustainable, it’s terrifying.

Scotland is luckier than most nations – though we do have some arable farming, for the most part we do good grass in Scotland and our soils are covered and stable.

So what can we do to cherish this most important of our natural resources? Even on our own small GYO scale, we can do a lot.

1 Organic growing uses nutrient and humus-rich manures and composts rather than chemical sprays to build soil health and fertility. This wonderful stuff acts like a ‘glue’ to stop soils drying out, giving them the rich, sponge-like texture that absorbs and holds water while still draining well. Organic soils are much less likely to turn to dust and be whisked away by wind and rain. It takes time to build a healthy soil after years of chemical growing, so start now. Get composting and gather up as many organic materials as you can – from fallen leaves to spoiled straw and everything in between - to rebuild the texture and vitality of your soil. Use organic matter for your mulches. Your veggies and the billions of soil microbes will thank you.

2 A bare soil is a ‘dead’ soil, so keep it covered. This is where weeds really come into their own (I’m only partly joking). If you need to have spaces between your veggies, think about a productive ground cover plant that won’t rob your main crop of the nutrients it needs. Or apply a light topdressing of mulch around your prize onions.

3 Try permanent planting – tilling the soil increases soil erosion, but permanent planting helps to stabilise and build rich, fertile soils.

4 There are some wonderful growing techniques like Permaculture and Biointensive Sustainable Mini-Farming which can build 20 pounds of soil for every pound of food eaten. Shouldn’t we all be trying them?

It’s no accident that the first organisation to lobby for organics called itself the Soil Association and that the seminal work by its founder, Lady Eve Balfour, was called The Living Soil.

A living, rich, bio-abundant soil is at the very heart of our health and wellbeing. Shouldn’t we all be doing everything we can to restore it, our planet and ourselves to full health?