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A Greener Life by Clarissa Dickson Wright and Johnny Scott. Photo by Vanessa Courtier

 

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  • Composting is the Holy Grail of the true organic believer. Photo by Vanessa Courtier

Looking after your soil: Clarissa Dixon-Wright's top tips

Clarissa Dixon-Wright

10th September, 2009

From weeding, to digging and composting, watering and mulching, get to know the good earth better

It is important to identify your soil type and whether it is acid or alkaline as this will affect what you can grow in it. Soil types range from sandy to heavy clay. To find out what you've got, take a small handful and rub it between your fingers and thumb.

Sandy or light soil

This will not stick together at all as there are large spaces between the soil particles. It makes it easy to work but sandy soils dry quickly especially in windy conditions.

They drain well but are difficult to keep together and will need manuring and having compost added. Sandy soil warms up quickly so is good for growing early crops but nutrients leach out of it very easily.

As this soil tends to be alkaline, add lime and check its pH every couple of years as lime washes away. Alliums and all root vegetables like light soils, as do salad crops, chard and spinach. Apple and nut trees thrive in sandy soils too.

Clay or heavy soil

A clay soil has a shiny surface and when rubbed between your fingers and thumb, the very tiny particles cohere. This makes it heavy to work and the soil sticks together like glue.

If allowed to dry, a clay soil sets and cracks like a piece of bad pottery, so mulch well in the summer to retain moisture. In cases of really heavy clay you may have to dig in sand.

Only cultivate clay soil in dry weather and see that your compost and manure are well rotted before you add them as decomposition will be slow due to lack of air in the soil.

Turn the soil in the autumn where possible so the frost will break it up. Peas and broad beans, strawberries, raspberries, pears and plums all like clay soil.

Silt

This tests like clay but without the shine. A silt soil is easier to work than a clay one but it gets sticky when very wet and turns to dust when dry.

Loam

The most sought-after soil, loam is a mixture of small and large particles. It doesn't stick together or fall apart but is like perfectly made pastry crumbs.

It is possible though to have a sandy loam or a clay loam. Loam holds moisture but also drains well. It is quick to warm and slow to freeze and all your fruits and vegetables will grow well in it.

Peat soil

This forms a brown springy ball between the fingers. It is formed from decomposed vegetable matter rather than rock, so it is very fertile but you need to watch the pH level. Peat is slow to warm up and to freeze. It tends to be neutral or slightly acid.

Once you have identified your soil you can decide what to grow. Having said all this I have to confess that I have never used a soil-testing kit and although I count some legendary gardeners among my acquaintances, when I rang round neither had any of them.

The most crushing rejoinder I received was from my friend Isabel who told me that she simply looked at the weeds to tell her about the acidity of her soil. This is a very good point and one I shall deal with opposite.


Acid versus alkaline

Soil may contain lime and the more there is, the more alkaline the soil will be. Certain plants thrive in a more acid soil, others do best in an alkaline soil, while yet others are best suited to a neutral one. Acidity and alkalinity are expressed as the soil's pH level. You can buy an inexpensive pH testing kit at any good garden centre to check the pH level of your soil.

  • above pH8 really means you're in a semidesert. Very little will grow in soil like this.
  • pH7 is alkaline and is usually found in hot dry areas. Most garden plants will survive but need regular cultivation with compost and manure. Brassicas, spinach, currants, apples, peaches and plums like an alkaline soil.
  • pH6-pH7 is neutral and most plant life thrives in it.
  • pH5-pH6 is fairly acid. This is typical of unimproved soil in wet areas. It is good for potatoes, tomatoes and fruit.
  • pH4-pH5 is acid. This is found in cold wet areas. There is little soil life or earthworms. Rhododendrons and azaleas do alright in it but it makes growing fruit and vegetables more difficult. You can add lime to make the soil more alkaline but take it easy, adding small amounts regularly rather than chucking heaps on in one go, which would scorch the roots.



    Mineral deficiencies

You will also need to 'read' your plants to discover what mineral deficiencies your soil may have.

  • Nitrogen deficiency: This is apparent when plants show small yellowing leaves and stunted growth. Check your soil's drainage - if you have land drains running away, make sure they are clear - and also make sure the subsoil is not compacted. If it is, dig it well and dig through plenty of compost and muck.
  • Phosphorus deficiency: The signs are small pale leaves with a bluish tinge that drop early. Add compost and check the drainage, as for nitrogen deficiency.
  • Manganese deficiency: The leaves fade as they mature. Add lime or chalk - but carefully.
  • Magnesium deficiency: The signs are green veins and yellow leaves. Add compost and/or Epsom salts.
  • Iron deficiency: You will notice that the leaves are yellow between the veins. Add compost and sulphur.
  • Potassium deficiency: The signs are browntipped leaves with yellow veins. Use comfrey slurry (see page 28) and dig in black banana skins.

    Weeds

The main problem with weeds is that they are competition to your carefully planted vegetables. The greatest threat is during the first four weeks after planting. If you can keep them away from newly planted seeds and seedlings during this time, you don't need to worry too much.

Some ‘weeds' are actually quite useful, for instance stinging nettles, fat hen and dock leaves are all great to use as pheasant and chicken feed.

Dandelions provide a delicious addition to your salad bowl as does chickweed.

The latter, made into a tisane, acts to clean the blood, as does pennyroyal, a type of wild mint that was once used as a substitute for tea. You shouldn't drink pennyroyal though if you are pregnant as it was once known as ‘the abortionist's friend'. Dried moss is another useful weed as it can be made into an effective bandage or poultice.

Weeds are also a good indicator of the state of your soil. So what to look for? Acid soils grow sorrel, plantain and knotgrass. Alkaline soils grow poppies and field parsley, whilst nettles of all types, chickweed, dandelion and borage indicate fertile soil.

Cow parsley grows where there is an excess of nitrogen and where there is too little, look for vetches and clovers. Compacted soils sport grasses while all types of buttercups, docks, sedges and mosses are signs of poor drainage.

Many weeds contain minerals and if they are dug up before they seed and are left to dry on the ground, they are useful on the compost heap. The dreaded couchgrass, for example, contains potassium as does yarrow which also brings iron, copper, phosphorus, nitrogen and sulphur. Dandelions, nettles, mayweed, bracken and horsetail are full of useful minerals and can be used for green compost.

Deep-rooted weeds such as nettles and docks have the advantage that they bring up nutrients from deep in the soil for more shallow-rooted plants. Their root channels also help break up the soil and aerate it.

Digging

If you possibly can, borrow a pig; if not, digging is a hard slog. If the ground is very hard and has been left idle, hire or borrow a rotovator. This will at least remove the hardship of double-digging in most cases. Remember, however, that digging is a much better and more longterm exercise for the muscles than going to the gym.

The trick with digging is not to rush into it willynilly and rick your back. Start gently and do no more than half an hour at a time until you have strengthened your muscles.

And always buy the best and strongest tools you can afford. You needn't spend a fortune; at county shows and game fairs you will find stalls selling all sorts of secondhand garden implements. I have often found a cracking selection of spades, forks and trowels, many of them much stronger than the latest gimmicky ones.

Spit digging

The most effective way of digging a plot is ‘spit' or ‘single' digging. The term ‘spit' refers to a spade's depth and width; the spade's shape and size has been developed to enable you to incorporate compost or manure into each spit or trench as you go along and before it is filled in.

You will want to do your digging in the autumn after the equinoctial rains but before the first frosts so that they will break up the manure you have dug into your trenches.

Divide your plot in half either mentally or with a stretched piece of string. Starting nearest the string and working at right angles to it, dig out a spade's depth and width of soil and place it on the other side of the string. Put manure or well-rotted compost into the trench you have dug then dig a second trench parallel to the first, putting the soil from the second trench on top of the manure in the first one.

Continue digging in this way the length of the first half of the plot. When you reach the end, dig in a reverse direction down the other half. The soil from your first trench will fill the one you dig last.

Double digging

Double digging (twice a spade's depth) is used to improve drainage and break up compacted sub-soil. It is particularly necessary when growing root crops. Mark out your plot in the same way as for spit digging and dig your trenches in the same way, but make each trench 60cm wide. When you have dug out the first trench, use a fork to break up the soil and dig out another spit's depth. Manure as before and fill in the trench.

Non dig method

As an alternative to all this back-breaking digging, there is a non dig method. Simply cover your patch of earth with a thick layer of compost and plant your vegetables into this. You can continue like this for 2-3 years, but after that you will have no option but to dig.

Composting

This is the Holy Grail of the true organic believer. Indeed, Lady Eve Balfour, the original organicist, had her spiritual awakening beside a compost heap in East Lothian, so it is very fitting - although they probably don't realise it - that East Lothian Council, where I live, runs a composting scheme to help and advise those who want to compost.

Once you have discovered the joys of composting you will never look back and will become quite obsessively boring (as I am) to those who haven't yet ‘crossed the line'.

Composting is caused by the presence of bacteria which need air, light moisture and nitrogen. Your heap (or temple of fertility) must stand on the earth so it can draw nutrients out of the earth as well as worms. If you stand it on polythene sheeting, it will rot and grow mould and fungi.

The optimum size for a compost heap is a metre square and 1-1.2 metres in height. You can construct one quite simply with stakes at each corner and chicken wire between or you can build a fine version with wooden slats for the sides, but remember to leave some space in between the slats to allow the air to circulate. I am not a great fan of purposebuilt composters but . . . ‘chacun à son goût'.

Choose the site of your compost heap carefully. Don't put one under drippy trees or they will keep to wet, nor in full sun as they will dry out too quickly. It is advisable to have three compost heaps - one ready to take compost from, one maturing away nicely and one that you are building up.

Build it up in layers of 15-25cm and do not have a layer of all one type of material, grass cuttings or autumn leaves for instance, as this will slow the process.

Mix each layer well like a fruit cake, then cover with a thin layer of garden soil to supply the bacteria and, if your soil is acid, a sprinkling of lime to keep all sweet. When the heap has reached the right height, cover with a layer of old carpet to keep everything warm. Some people recommend plastic sheeting but I think that makes the heap too wet.

If the weather is exceptionally dry you may want to sprinkle the heap with water. A finished compost heap needs about six months before it is usable and after three months, if all your power sources fail, it's so hot you can cook in the middle of it, using the haybox principle. A compost heap in my village made only of grass cuttings spontaneously combusted once and burned, leaving the owner with nothing but ash!

Some people put autumn leaves on their compost heaps but I prefer to keep them separate and allow them to do their own thing and form leafmould. It takes about 2-3 years to make proper leaf mould from the leaves of deciduous trees but is worth the wait. You can speed up the process by keeping your leaves in plastic bags for about a year. Personally, I prefer the slower-matured variety.

Something else you can do is to grow lots of comfrey round the edges of your vegetable patch. This makes a wonderful addition to your compost heap as it helps the decomposition process. And add a few earthworms to your heap as well as they are great for breaking everything down and encouraging the bacteria.

Manure

Don't balk at the thought of manure; if it is well rotted it doesn't smell nasty or indeed very much at all. One of the problems in organic vegetable growing is obtaining organic manure, in other words manure from cattle or pigs that have been raised organically. As the organic movement grows this naturally becomes easier, but it is still quite hard to find and expensive.

Organic fertilizers used to be made of bone or fish meal which have now become pretty well illegal in the European Union. In any event organic fertilizer used to attract foxes who dug it up and ate it, thus ruining your planting.

You cannot use fresh manure in your trenches as it needs to rot down. If it is not well rotted it will burn the plants. If you have your own animals you will have a regular supply of organic manure after the first year but it is worth buying it in to begin with. You can obtain horse manure from a friendly riding stables.

Although horses are not eaten as food in England and consequently are not raised organically, there is not much in their diet to offend, so unless you are going for commercial organic status I'd use bought horse manure in year one. Personally I have always found the finest manure is well-rotted pig manure.

You can use spent mushroom compost instead of home-produced compost. I once had a car that grew mushrooms when it rained as a sack of mushroom compost I had in the back leaked and wasn't completely spent.

Chicken droppings are another alternative. It makes a very good manure for vegetables. Don't dig it in fresh but keep it for about three to four weeks. Grass cuttings are yet another possibility. You can put them into a bed intended for potatoes. Lay them at the bottom of the trench and fill in on top.

Watering and mulching

Never water in full sun as this will burn the leaves of your plants. Early morning is best before the sun has any heat. The evening is also good but if the plants stay wet all night this may promote disease.

Water closely around the roots so that the water doesn't dissipate, and on the leaves as well. Water needs vary with the different plant; brassicas for instance need 10-15 litres a week in dry weather, whereas legumes don't need much watering at the seedling stage as this promotes leaf growth at the expense of flowers and pods.

Once the pods are set however, they need watering to promote internal and external pod growth. Ten litres of water per square metre per week applied twice daily in dry weather is about right.

A good way of feeding the plants whilst watering is to fill a rain butt with water and throw in a good quantity of comfrey. Leave it to stand for a week or so and use it for watering.

Use it in the ratio of about one part comfrey slurry to three or four parts water. You can also throw manure into your rain butt which gives arich feed, but use this sparingly and do not water the leaves with it.

Mulching, the practice of applying compost or leaf mould around the plants, is another good way of retaining moisture and keeping down weeds. Apply after the seedlings are well up. It is easy to remove any wind-blown weed seeds from the soft surface. Don't feel romantic about weeds; they leach both moisture and nutrition from the soil at the expense of your vegetables.

Do not put on your compost heap

  • Eggshells as they will attract rats.
  • Any vegetable waste attacked by blight, i.e. club foot in brassicas, alliums suffering from white rot, blighted potatoes etc., as the disease may stay in the compost and be disseminated.
  • Woody vegetation such as clippings from trees, shrubs or fruit bushes, as this will slow down the decomposing process. If you have a proper shredder you can in theory add them, but I find the twiggy bits irritating when sieving the compost. Burn them instead, have a lovely bonfire, dance round it, roast potatoes in the embers and you'll have nice ash to use as well, which will help keep out slugs as well as providing fertilizer.

 

This is an extract from A Greener Life by Clarissa Dickson Wright and Johnny Scott (Kyle Cathie, £16.99) with photography by Vanessa Courtier.

Ecologist readers can buy the book at the special price of £14.99 inc free p&p (UK mainland only).

To order your copy, ring: 01903 828503, quoting ref. KC AGL/ECO or email: mailorders@lbsltd.co.uk

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