How to Improve Soil!

It may be just dirt to some people but the soil you grow your fruit and vegetables in is critical to the success of your crops. Having a basic understanding of your soil type, its level of fertility and pH will allow you to take specific actions to improve your soil both generally and to tailor it for specific crops.

All soils are made up of 3 basic ingredients in varying quantities:

  • Clay

  • Sand

  • Silt

    The relative amounts of each of the above will determine the type of soil you have and how it should be treated.

    Soil Types...

    Clay Soil

    These soils are ‘heavy’ but fertile. Clay is a critical element in all soils because its unique layered structure at molecular level is negatively charged. This allows it to capture positively charged nutrients such as nitrogen preventing them from being washed or leached out of the soil. The captured positively charged nutrients are only released when plant roots produce positively charged atoms which are swapped for the nutrients.


    So clay in soil is generally a good thing. That’s said too much and your soil will be sticky and difficult to work and as the clay particles pack closely together particularly if you walk on the surface the soil will have very few air pockets in it which the plants roots need to survive and grow. In spring a heavy clay soil will be water logged and cold while in summer it will dry out and crack badly.

    Dealing with a clay based soil requires you to dig in quantities of well rotted manure and for smaller areas applying course grit will help increase drainage.

    Sandy Soil

    Sandy soil is light and free draining but is very poor at retaining nutrients and holding water during the dry summer months. In the spring it warms up quickly which ensure that plants get a good start but unless fed and watered regularly they then can fall back.

    To improve a sandy soil add large quantities of organic matter such as peat or well rotted manure and mulch the soil regularly throughout the season to prevent water evaporation.

    Silt Soil

    This is a soil where the particles are bigger than clay but smaller than sand. This type of soil is fertile and reasonably free draining but like clay soils are easily compacted.

    Working with a silt soil is similar to a clay soil but less difficult. The quantities of organic matter and the need for the application of course grit are less.

    Loamy Soil

    Loamy soils contain good quantities of sand, silt and clay and are in many ways the best soils to start with. They are good at holding nutrients, free draining and fertile. They warm up quickly in the spring and yet retain water reasonably well during the summer.

    pH – What is it and why is it important?

    pH is a measure of the acidity/alkalinity of your soil. The scale runs from 0 to 14 with neutral being 7. Anything above 7 is considered to be alkaline anything below this is acid.

    Most plants prefer a neutral to slightly acidic pH (down to approximately 5.5) although many will tolerate a slightly alkaline pH (up to 7.5).

    Testing the pH

    If you are starting a fruit and vegetable garden from scratch it is worth testing your soil to see what the pH is. This is easily done using a readily available test kit. Simply mix a small amount of soil with water, add a test chemical and see what colour the water changes to. Compare this colour to a chart provided to see what the pH level is. Depending on the result it is possible to adjust the pH by the application of chemicals such as lime which is used to raise the pH particularly in brassicas to ward off club root problems and provide good growing conditions.

    Digging – Why and how to do it

    Once you have assessed and tested your soil it will need working to variously incorporate organic matter, fertilisers, course grit etc. to prepare it for planting. While this can be physically demanding it is the only way to ensure you get a good crop year after year.


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