Topsoil is the name given to the uppermost layer of our earths surface, This fine layer, often only 15cm in depth is what gives life to all plants, flowers & trees on our planet and is home to hundreds of thousands of different insect species.
The surface layers of our planet are broken into 5 distinct regions, O, A, B, C & R. O stands for the Organic layer – this is the layer of decaying organic life that will eventually breakdown into humus in the earth’s topsoil layer. A is the topsoil layer and this is where plants & insects are most active. It is in the topsoil layer where plants can obtain all the necessary plant nutrients, air & water. What makes one topsoil better than another is the balance of water, air & the availability of nutrients
Topsoil Facts
- Topsoil is home to a huge variety of life from micro organisms to earthworms, insects & burrowing mammals. This diversity makes topsoil a very important ecosystem
- 1 teaspoon contains over 1 billion bacteria
- Soil is basically a substrate that contains all the essential elements for root & plant growth. These being water, air & nutrients. The ideal balance of these elements in soils is 25% water, 25% air, 45% soil substrate & 5% organic matter (humus)
- Soil is an endangered natural resource. Through poor agricultural practices, intensive farming, deforestation & flooding, we are destroying this precious resource at an alarming rate. Currently approx. 40% of the worlds topsoil is considered ‘degrading’ & at current rates it has been suggested that within the next 70 years we will have destroyed 99% of the earth ‘growing layer’
- It takes 1000 years to make 1″ of topsoil. The processes under which topsoil forms, involves the weathering of bedrock material (limestone, sandstone, etc) & the decomposition of organic material (grass, forests, insects, fish & animals)
- The A layer stores carbon dioxide – It is believed that 10% of the worlds carbon dioxide is stored in topsoil. As our topsoil is degraded, this carbon dioxide is released into the atmosphere
- Some of the bacteria & fungi in soils has a symbiotic relationship with plants. These micro organisms sit on plant’s roots are allow roots absorb essential plant nutrients that would otherwise be unavailable to plants
- The tallest of coniferous trees only require a 30cm layer to grow & achieve their soaring heights
- If soil degradation is not controlled in the next 20 years it could lead to a drop in worldwide food production of up to 30%
Because soil is such an important natural & limited resource, we need to do everything possible to maintain it & protect it. In the garden there are a number of simple steps that we can do to ensure the quality of our soil is maintained. A lot of these principles are the corner stone of organic gardening
- Reduced cultivation
- Excessive cultivation can lead to soil erosion, death of earthworms & micro organisms
- When preparing vegetable plots you should only loosen the top 3″ of soil – Leave the rest to rest!
- Use of cover crops in winter & green manure
- In winter, bare soils are a problem
- Bare soils mean less insects in your soil & more risk of soil erosion
- In autumn, once you have harvested your crops you should sow green manure on your plot
- Reduce & control use of chemicals
- Crop rotation
- Use of soil renewal products such as soil renew & use seaweed based fertilisers
- Protecting the earthworm
- Earthworms are essential for healthy soils. They improve air air flow & drainage, they help to breakdown organic matter & they help to recover soil nutrients
- Protect earthworms by reducing cultivation, reducing chemical usage & by using garden forks instead of garden spades
- Avoid mixing soil layers
- Top soil is distinct from subsoil in many ways (most notably colour). When working soils, digging & renovating homes & gardens it is essential to not mix topsoil & subsoil
- Stay vigilant to invasive weeds
- Always be on the look out for weeds such as mares tail & Japanese knotweed. These weeds will quickly take over soils & render them useless
- If you find mares tail & Japanese knotweed, please contact the garden shop for advice on how to remove it safely & effectively