Know your Plot: Soil

Improvement

Not all soil is created equal.  And good soil can make the difference between your crops failing, wasting a year’s hard work and a bumper crop that takes first prise at your local allotment show!  Knowledge is the first key to improvement; hard work is the second key.  Whatever your soil type, location or pH balance; you won’t go far wrong by digging in some well rotted manure and making sure your ground is well fertilised throughout the year!

Soil type

Identifying your soil type is easy. Grab a small handful of soil and try and mould it into a ball, if it crumbles in your hand and feels gritty when you work it, then it is most likely sand.  If you succeed in making it into a ball then it may be loam – unless you can work it further into a sausage shape and bend that shape around your finger – then you have clay.

It’s quite a messy job but I find my kids love doing this test!

Clay

Clay is hard work, but once it has been worked it is a very rewarding soil type.  It holds the nutrients vital to the growth of your plants and will stay moist even throughout a dry spell.  Drainage can be a problem with clay, particularly if the clay has been compacted by walking on it, poor drainage will exclude air from the roots of your plants and will effectively drown them.  Also, clay can be slow to warm up after the winter and this should be taken into consideration when planning your planting calendar.  You can generally improve the soil by digging in organic matter such as leaf litter and manure.  This will bring it closer to the soil type loam (see below). 

Sand

Soil that is sandy at first seems like a gardeners dream; it is easy to work and will drain well even after a heavy downpour.  But plants sown directly into sandy soil without first boosting the soils nutrients are unlikely to do well.  If you have sandy soil, plant your crops earlier and water often in the summer.

Loam

Something of a holy grail for gardeners.  It combines the best elements of sand and clay.  Unfortunately loam is a very rare sight in an unmanaged plot; but fear not, with a little work digging in organic matter such as farmyard manure, wood bark or leaf litter you can transform sand or clay into beautiful loamy soil – the perfect conditions for most vegetables.

Soil pH level

Not all soils are equal in terms of acidity and alkalinity or pH balance.  You will generally find that most soils are in a pH range of 5.5 and 7.5 and crops will grow best when your soil is close to pH 6.5 or slightly acidic soil.  This is because soil at a pH level of 6.5 allow the most nutrients to be taken in by the plants roots.

There are two ways of testing your soils pH balance.  The first is to send off a sample of your soil for analysis at a lab.  This is going to give you the most accurate answer – but its not an instant answer and is likely to be significantly more expensive than the second option, which is to get a DIY litmus test from your local garden centre.  The DIY kit is basically litmus paper which changes colour according to the pH level of something it comes in contact with.  Simply match the colour with the provided chart and hey presto – you have your pH level!

So, you know the pH level of your soil and you know that the ideal pH level for your plants to thrive.  But how do you alter the pH level of your soil to the optimum?  Read on...

Making your soil more alkaline is easily achieved with an application of lime to your soil.  You will need about 4.5kg of lime for every 9 square meters of soil (or for imperial the equation is simply 1lb of lime per square yard).  Dig this into your soil and it will increase your soils pH level by one point (ie from 5.5 to 6.5).

Making your soil more alkaline is more difficult however.  This is because usually the reason for alkaline soil is because of where the soil is derived from.  For instance, if it derived from chalk then it will have a constant supply of calcium to leach back into the soil restoring the alkalinity.  Using sulphur instead of lime in the above quantities will have a short term affect on the soil pH level.  But digging in plenty of organic matter will be the best solution.

Location/weather effects

Ok, so you have done the best you can to make the soil as loamy as possible with a pH level as near as 6.5 as possible.  Now for something you can’t change, the weather – so you must be mindful of it.  Firstly if you have sited your crops where they are likely to get less than 6 hours of summer sun than forget it, it’s unlikely anything will come of them.  Your crops will need as much sun as you can give them.

Cold air and frost pockets can be damaging to plants by stunting growth in the outset and damaging crops later in the year.  You can alleviate some of these problems with the use of gardening fleece and cloches. But try planting your crops away from low lying hills or where walls and hedges meet, as cold air is likely to collect here and reduce the temperature by a degree or two.

Flora/fauna

Most wild life believe it or not is good for the garden. From worms that break up and enrich the soil to hedgehogs and foxes that will control your pest population.  Remember: in garden you are tweaking an ecosystem that has worked - and will continue to work - for millennia without your help.  Tread lightly and reap the rewards.