The feel, water retentive properties, pH, nutrient content, trace elements and micro organisms and fauna (such as worms) in your soil are crucial to growing and growing healthy plants. However, as soon as you’ve got the balance right and understand how to keep it, you’ll be growing vegetables that are fantastic.
pH Values Explained
Briefly, soil is classed as either acidic, neutral or alkaline. This variety is measured on what is known as the pH scale from pH1 (very acidic) through to pH 14 (very alkaline) Neutral is pH 7. For example a pH of 6 could be considered slightly acidic or a pH of 8 could be slightly alkaline.
It’s possible to discover the pH value of your soil via an easy test which can be purchased from many garden centres and stores. I would strongly recommend completing 1 or more tests in your own vegetable plot to determine the pH of your soil as it will let you determine if your soil pH needs improving, or is acceptable for the vegetables that you want to grow. The test is usually done using a corresponding color chart. Results which are red, orange or yellow are acidic (pH below 7), green is neutral pH 7, blues and purples are alkaline (pH above 7)
In general terms soils comprise of particles which vary in size, the smallest are clay particles, then there are the slightly larger silt particles, and lastly, sandy particles being the biggest. These particles blended together constitute distinct grades of soil. There are seven primary soil types. Which one best describes yours?
- Clay soil
- Heavy Loam
- Medium Loam
- Sandy Loam
- Sandiger Boden
- Chalky / limestone soils
- Peat lands
The Qualities of a clay soil are:
- Consist of very little particles, or grains (less than 0.002 millimeters in diameter!)
- These little particles fit together quite closely with few spaces.
- These particles easily aggregate (stick together) when moist.
- Insufficient air spaces signifies poor aeration and bad drainage.
- Clay soils are slow to heat up in the spring.
- Clay will be high in nutrients, but the soils structure means that these can be inaccessible to plants.
- Wet clay is sticky and greasy to the touch.
Dry clay is strong, hard and lumpy.
- Clay is generally neutral in pH (pH 7)
- Tend to be tough to work.
The Qualities of a sandy soil are:
- Consists of large particles, or grains (apx 0.05 up to 2mm in diameter).
- These grains have loads of air spaces between them.
- The grains don’t aggregate (stick together) easily so water drains easily.
- This draining can lead to nutrients being washed off (leaching).
- Sandy soils are usually low in nutrients.
- Sandy soils tend to be acidic (pH of less than 7)
- They feel gritty to the touch
- Sandy soils are usually light in colour.
- They are quite simple to operate (dig).
- Sandy soils warm up fast in the spring.
- They do dry out quite quickly in the summer, getting dusty.
The characteristics of chalk soil are:
- Tend to be pale in color.
- They also have a tendency to be shallow in depth.
- Chalk soil is generally low in nutrition.
- Can be sticky when wet and lumpy when dry.
- These are often quite acidic and not acceptable for most plants.
- Tend to be rich in organic matter.
- May get waterlogged.
(Varying from sandy to heavy). The best lands are called friable loam. These have a fantastic balance of clay, sand, organic matter and nutrients.
These lands are easy to operate, have good rich color, and have a crumbly texture, and great drainage.
Okay, that is the soil types and I’m sure you’ve worked out which one bests describes yours and you have some idea of the pH of your soil also. Now in the event that you’ve got a lovely friable loam soil with a pH in the range of 6-7 then blessed you!!! If however you don’t then don`t grief. Whatever dirt you have it can be enhanced for your vegetable growing or we can use methods on really shallow or poor lands such as raised beds.
Sandy soils can be improved by the addition of organic matter (well rotted farmyard manure, compost, as well as seaweed). These can be dug in to improve the soil structure, help water retention and consequently may encourage beneficial soil organisms. Adding organic matter will include nutrients but further feeding with fertilizers may be necessary.
Clay soils are also significantly enhanced with the addition of organic matter, as this helps to prevent the particles sticking together, adds air spaces and improves drainage. Sometimes the inclusion of horticultural grit are also of advantage.
If your soil pH is less than 6 then you want to increase the pH a degree or two. This may be accomplished by the addition of lime, the amount used depends on how much you will need to increase the pH by.
If your soil is high in pH (above 7) then to attain the reverse and lower the pH you can try adding wood shavings, or flowers of sulphur.
It’s unlikely a pH change of over 1-2 levels will be possible with these methods, and the consequences will be short lived and will likely have to be repeated to keep the desired pH.
Micro Organisms and Soil Fauna
These are underestimated in their importance to plants. Just what are we talking about this? Well soil is filled with little organisms and creatures. Some are good for soil and are known as beneficial soil organisms. Some aren’t so good or harmful soil organisms.
Beneficial soil organisms include earthworms, some bacteria, some fungi, some nematodes (simple worms), some beetles, and protozoa. Each of these plays an essential role in your soils environment. A soil which has many earthworms is a great sign.
Harmful soil organisms incorporate some nematodes, wire-worms, eel-worms, and the dreaded slug.
If your plot suffers from poor drainage in spite of a better topsoil, then you might have an underlying problem perhaps a layer of hard-pan (impermeable layer of subsoil) under your topsoil or maybe the water table (the top layer of water in the floor beneath a well drained topsoil anytime )) is obviously near the surface.
It might be in this case that a drainage system may be required, or that the hard-pan will have to be broken up. An easy drainage system would require digging little trenches into which pipes are laid resulting in a soak-away or other drainage system.
For vegetable growing you’re going to require a good 18 inches or 45cm depth of viable, free draining soil (roughly 2 spade depths). If the coating of hard-pan is unbreakable or the water level to high, or a drainage system not possible, then building raised beds might be the solution.