Improving Fertility of Your Soil
You improve the fertility of your soil by adding materials that provide a range of nutrients that your plants need for healthy growth.
The main kinds of materials you may need to add to the soil are :
- Manure
- Lime
- Fertilizers
Adding Manure
Manure comes in a number of different forms including, for example:
- Garden compost (See Composting)
- Farmyard manure
- Peat or peat substitute
The purpose of these products is to increase the level of humus in the soil - that is partially decomposed organic matter along with the hordes of beneficial bacteria that act to break down this material. The final result is improved soil structure along with valuable nutrients that are slowly released to feed and help your plants to grow strong and healthy. Ideally you should add these materials to the soil when you are digging it over.
Adding Lime
Lime is an excellent soil conditioner and because it tends to be washed away by rain, it is important to replenish it on a regular basis. Lime can be applied in a variety of forms but perhaps the most common and easiest to handle is hydrated (or slaked) lime.
The benefits of lime include:
- It reduces the acidity of the soil
- By reducing the acidity, lime also makes your soil more attractive to beneficial bacteria and worms
- In clay soils, lime helps the particles of clay to bind together into 'crumbs' and thereby improves the structure of the soil
- The main ingredient of lime, calcium, is an important plant nutrient
- Lime discourages some of the gardener's greatest enemies such as wireworms, slugs and leatherjackets.
It is important to add lime to the soil but not to add too much. The best way to determine correct quantities is not to guess but to use some kind of test to establish the level of acidity in the soil (see Testing Your Soil).
You should aim for a more or less neutral soil – not too alkaline and not too acid. The degree of acidity is measured in terms of pH level, where a value of 7.0 indicates neutral, anything less than 7.0 indicates acid and anything over 7.0 indicates alkaline.
In practice, it isn't necessary to hit exactly 7.0 but a value between say 6.5 and 7.3 should suit the majority of garden plants.
Of course if you wish to grow particular plants that are either acid loving (such as azaleas or hydrangeas) or that are alkaline loving (such as Carnations or Delphiniums) then you may need to adjust the pH level of that part of your garden by adding peat (for acidity) or additional lime (for alkalinity).
Adding Fertilizers
There is a bewildering array of fertilizers available at any garden centre or nursery. Some are general-purpose fertilizers such as the well-known Growmore. There are many others that are sold for specific purposes such as lawns, roses or tomatoes.
The purpose of fertilizers is to replenish the nutrients that have been removed from the soil by the previous season's crops. Of these nutrients, the three that particularly need to be replenished are:
- Nitrogen – which is particularly important for leafy plants such as grass, and leafy vegetables. If your plants are showing stunted growth or pale leaves, the chances are they are short of nitrogen
- Phosphorus – which helps to promote strong root growth and therefore is particularly important for root vegetables and, indeed, any plants that are young and in the process of developing their root structures. Clearly a shortage of phosphorus will result in stunted growth and low production
- Potassium – which improves resistance to disease and helps with the production of fruit and flowers. A shortage of potassium will result in diseased plants and low yields
Apart from the three main ones, other nutrients and trace elements that your plants need include: calcium, magnesium, sulphur, iron, molybdenum, boron, zinc and copper.
For the majority of gardeners who are adding plenty of manure to their gardens, along with a good general-purpose fertilizer and perhaps lime dressing, most if not all these additional elements will be present in sufficient quantities for healthy growth.
Read more about Types of Soil |
Read more about Soil and Climate |