Understanding Different Soil Types

Understanding the soil in your garden is vital to producing a successful crop.

Different plants have specific needs from the soil they grow in.

While some plants are best suited to fertile soil, others may produce excessive growth at the expense of flowers and fruit. In addition, some plants may require constantly moist soil, whereas others will quickly rot if exposed to too much water in the ground.

When choosing plants, you must first know what type of soil you have and whether to alter the soil structure beforehand or add extra nutrients. The best way to find out about the soil in your garden is to pick up a soil testing kit and grab your spade!

Read also: Growing Unusual Fruit and Vegetables

Let's dive right in.

Table of Contents

Soil Structure

The first and most obvious thing you will need to examine is the soil structure. Your garden soil will generally fall somewhere between three main categories; clay, loam, or sand.

Clayey soils are usually nutrient-rich due to poor drainage, and the nutrients do not leach away. However, this also means that clay soils can quickly become waterlogged and may not suit plants that require good drainage.

On the other hand, loam soils have a good balance between clay and sand particles. They are the happy medium, retaining moisture and nutrients but not too heavy to prevent water from draining away.

Sandy soils are generally poor in nutrients due to the leaching action as water passes through the soil. Also, sandy soil is more prone to soil erosion during dry spells on exposed areas as the soil dries out much faster than other types of soil.

The easiest way to find out which soil category the stuff in your garden falls into is to dig some up and squeeze it. Be sure to dig down a fairway and test the soil at different levels as your topsoil may have a different consistency to your subsoil. If it crumbles apart immediately when you relax your hand, you will have sandy soil; if it stays in a clump but breaks apart easily, then your soil is a well-balanced loam. If it stays in a clump even after handling, then you'll have heavy clay soil.

Whatever type of soil you have, you can take remedial action to improve its structure. For example, grit can be added to heavier soils to aid drainage, and you can add organic material to sandy soils to improve water retention and replenish lost nutrients. In extreme cases of waterlogging, you can take further action to improve the soil drainage by building drainage channels.

Soil pH Levels

The pH levels of soil will determine which plants can be grown there effectively. A pH value of around 6.5 to 7.0 is considered neutral. A lower pH value means a more acidic soil, whereas a higher pH means a more alkaline soil. Outside of the neutral range, some of the nutrients within the soil will form chemical compounds, which will make them unavailable to your plants. Some plants will tolerate or even prefer more acidic or alkaline soils, but the further your soil strays from neutral, the harder it will be to grow a wide range of plants in your garden.

A soil testing kit will help you determine the pH of your soil (some testing kits will help you determine the nutrient levels in your soil). If your soil falls outside the neutral range, you can take remedial actions by adding lime if it is acidic or adding sulfur if it is alkaline. In extreme cases, you should consider container growing, where you will have complete control over the soil classification.

Soil Nutrients

The final factor when examining your garden soil is the nutrients it contains. Plants require around 13 mineral nutrients, which they draw from the soil. The three main nutrients needed for good growth are nitrogen (N), phosphorous (P), and potassium (K). Different plants have different requirements for nutrients; indeed, some plants will suffer if too many nutrients are available in the soil. A decent soil testing kit will give you information on the nutrients in your garden soil as well as the pH levels of the soil.

If you find your soil lacks nutrients, you can incorporate organic matter to improve the soil or consider using fertilizer. Commercially available fertilizer will usually carry a statement describing the nutrient balance (ie, 5-10-10, which represents percentages of N, P, K in the fertilizer); selecting the right fertilizer allows you to counter any soil deficiencies. You can also try making your soil conditioner and fertilizer; liquid feed from brewing nutrient-rich plants such as nettles or comfrey can add a much-needed boost to some soils. In addition, Leafmould will add bulk to sandy soils and help break up heavy clay soils.

Another approach is to select local plants or vegetable varieties that will thrive in your soil. Take a look around at what grows wildly, or look up native plants. The Natural History Museum has a 'Postcode Plants Database' that enables you to generate a list of local flora and fauna, helping you to discover just what plants are suited to your location and soil type.

When you have some spare time in the garden, then take a moment to examine your soil. Get to know more about its structure and the soil pH and nutrient levels if you have a testing kit. Understanding your soil will allow you to select the right plants for your garden and counter any potential problems before they appear.