Concern over the degradation of our soils is mounting. In this article, I want to give you practical ideas of how you can maintain and even improve your soil as we mark #WorldSoilDay on December 5th 2019
If you've read part one, you'll already know how important soil health is to us as gardeners and to the whole of humanity.
There's no shortage of things that we can do to get our soil into good shape. Here, I'll talk you through the plenty of options you can choose from. We'll be looking at natural fertilisers, mulching materials, and even growing green manures.
Rough dug garden soil covered in frost
Natural fertilizers and soil improvers
- Farmyard manure is the most widely available natural fertiliser but can be hard to source in large quantities.
- Bagged farmyard manure should be available from any reputable garden retailer. If you have a large garden, this is an expensive way to acquire it.
- If you live in the countryside, you may be able to source bulk quantities. However, farmers are increasingly looking to incorporate as much farmyard manure into their own soils as they can so may not want to part with it.
- The animals that produce the manure can be relevant. Poultry, pig and horse manure is high in nutrients. Manure from cattle is less fertile.
Cattle produce god manure for gardeners
- Farm animal bedding is also relevant to gardeners looking for good farmyard manure. Straw is excellent, but care should be taken to check that persistent herbicide residues are not present. Wood shavings and sawdust are also good but can take longer to decompose.
- Bedding that contains high fibre content may 'lock-up' nutrients - especially nitrogen - as they decompose, temporarily robbing plants of this vital nutrient.
- In practice, nutrient levels in farmyard manure are relatively low when compared to both dry-organic and man-made fertilisers.
- Seaweed can be an excellent natural fertiliser, and it contains many of the minor nutrients needed to grow healthy plants. If you live close to a beach and collection of seaweed is permitted, then this can be a free source of plant feed.
Seaweed mulch on a vegetable plot on Iona
- Waste products are produced by many manufacturing processes. The food and drinks industry can be a source of inexpensive natural fertilisers and soil improvers.
- From the brewing of beer, 'brewer's grain' may be available.
- From cider manufacture 'apple pulp' might be obtained.
- Less common, 'shoddy' - the dirty off-cuts from sheep fleeces - can also be used as a soil improver.
- Many of these waste products are perhaps best added to the compost heap before applying to the garden.
Other soil improvers; organic matter
Garden compost bins covered with old carpet
- Garden compost is, of course, the best source of organic matter for most gardeners. What could be better than recycling the nutrients in your plant prunings back into your soil?
- Read more about making good compost here:
- Green Waste might be an ideal compost source if you're not in the countryside.
- Roadside collection of green garden waste combined with professional composting on an industrial scale has revolutionised the green waste supply.
Steaming pile of green garden waste
- Bagged composted green waste is available from most garden retailers and from some local authorities too.
- However, since there is no mechanism in place to check for the presence of heavy metals and herbicide residues, this may not suit every gardener.
- Leaf mould is a fantastic form of organic matter, but very difficult to obtain. You can always make it yourself!
Filling refuse sacks with leaves to make leaf mold
- Composted bark is readily available and an excellent way to improve soil, by adding as a surface mulch or digging into the ground.
- Avoid bark peelings and wood chip unless you're going to allow it to decompose before use. It generally contains too much lignin, which needs to break down before being added to soils.
- Peat used to be popular. However, harvesting peat has terrible environmental consequences, so should be avoided.
- Coir to some might be an acceptable alternative to using peat, but this material is not without its adverse environmental implications.
- Spent mushroom compost is an excellent soil improver and has the added advantage that it is free of weed seeds. You can buy this in bulk, making it especially suitable for allotments.
- Regularly covering the top five to seven centimetres of your soil with an organic mulching material will improve the soil structure.
A garden border with mulch
- Earthworms pull this mulch underground and turn it into humus. This releases nutrients and improves the soil structure.
Green manure crops
- Green manure crops trap nutrients, preventing them from being leached out of the soil.
- A green manure crop can have immense benefits to soil structure and the organic content of soil.
Red clover green manure crop
- A crop covering the soil in winter will reduce water runoff and therefore also reduce soil erosion.
- Any fast-growing crop is suitable to be sown and dug into the soil before it flowers.
- Much of the benefit of these crops is from the extensive root systems that they have. The top of the plant can be shredded with a lawnmower before it too is dug into the soil.
- Fast-growing grazing rye is a popular choice for green manure, as are field beans, clover, fenugreek and alfalfa.
- Mustard is particularly suited to covering soil quickly but it is not winter hardy.
Mustard green manure