Leaf mould

Fallen leaves

Deciduous trees lose their leaves in the autumn (fall). These falling leaves can be a nuisance – they can clog ponds, bleach patches on the lawn and cause paths to become slippery. Collecting them up is an annual chore for many gardeners, with leaves being stuffed into plastic sacks and left out for waste disposal.

You may feel a little better about the chore if you make use of your leaves to make leaf mould (or mold). Leaf mould is a simple compost that is made only from leaves, and when it is ready it makes a great low-fertility soil improver, or a mulch, or a perfect addition to homemade potting compost. Leaves that fall on borders and beds that are to lie fallow over winter can be left in place to cover the soil surface and protect it from bad weather, and then removed for composting in the spring.

DIY leaf mould cage

Making leaf mould is very easy, as all you have to do is collect leaves and store them long enough for them to rot down (which can be two years, or longer). A traditional leaf mould ‘bin’ can be made from a chicken wire cylinder supported by four stakes in the ground – allowing air and water into the leaves helps them to rot down more quickly.

Alternatively you can collect leaves in plastic sacks, make a few air holes in the sacks, then store them in a quiet corner until they’re ready. Ideally the leaves would be wet when you collect them, or you can add a little water before you close the sacks.

Only collect deciduous leaves – evergreen needles and clippings can be kept separate for use as a mulch for acid-loving plants. Some species take longer to rot down than others. Don’t use leaves that have been contaminated with road dirt, and don’t collect leaves from woodlands – they are needed there are part of the natural ecosystem.

If you want to speed up the process you can run the mower over the leaves before you collect them, as chopping them helps to speed up decomposition.

After a year or so your leaf mould may be mature enough to use as a soil improver or mulch. After another year it will look more like compost, and can then be used as part of potting mixes. The longer you leave it, the finer it will be.

Soil sterilization

The advantage of commercial seed composts is that they are sterile – the ingredients have been sterilized to kill weeds, pests and diseases. Small-scale sterilization at home seems to be reasonably common in the US, although I haven’t come across anyone who does it here in the UK. Pasteurization is the same process but uses shorter ‘cooking’ times or lower temperatures, and kills weeds and pests but not all of the microorganisms – many of which are beneficial.

If you’re a Garden Organic member then you can find out more about soil sterilization and pasteurization via the member’s section of their website. There is also useful information on the Colorado State University Cooperative Extension site.

Commercial soil sterilization is usually done with a steam sterilizer, and I believe smaller versions are available if you have a reasonable volume to get though. But most home sterilization is done using either the microwave or the oven – both of which risk alienating your loved ones as there is a smell issue and the ovens will need cleaning well after use. Also, if you’re using the microwave, be sure to remove any stones as they could explode. Apparently you can also use a pressure cooker….

If early attempts get you banned from the kitchen, or you’d like to try a low-energy approach, then you can try soil/ compost solarization. This involves spreading a thin layer of soil or compost out and covering it with a clear plastic layer. Heat from the sun then slowly sterilizes the soil. Very slowly, I would imagine, in an average English summer – there’s probably a reason why it’s more common in California.

Urine
Composting Toilet

Urine, as human waste product, can be problematic. Flush toilets use a lot of water (often purified to drinking standard), which is expensive to treat and pump and in increasingly short supply. Nitrates in human urine can make their way into water courses and cause pollution; denitrification is an expensive and energy-intensive procedure. And taking crops from your garden and not recycling the nutrients in your waste products (although using humanure is a step too far for most gardeners) means that you’re breaking the nutrient cycle – and those nutrients need to be replaced or your plants won’t thrive.

Urine is acidic and can be salty, but it’s safe to use as a liquid fertilizer if you dilute it. 10 parts water to to one of urine is a good general mix. Don’t go any lower than 5:1, and use weaker solutions on seedlings.

The one to three litres of urine produced by an adult every day should be enough to fertilize 300 m2. Use it fresh, as the nitrogen content decreases (and the pong increases!) during storage.

While it’s safe to use urine as a compost activator, don’t add it to a wormery, as it is acidic and will bother the worms.

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