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If you are interested in growing healthy strong plants, whether for aesthetic reasons or to eat, you should be thinking about using manure in your garden1. If you are a vegetable grower with good taste and healthy living in mind, you should definitely be adding manure to the soil. It is a cheap and natural source of all things that are good for your soil and you should never have to buy a bag of chemical fertiliser again.
But what kind of manure is available? Can it be used fresh? In what quantities should it be spread? At what time of year should it be put onto the garden? Where can you get it? How much does it cost? All these questions, and more, are about to be answered.
Nature's Recycling System
Manure is the oldest and most effective soil fertiliser known to man. Not only does it fertilise the soil, but it also conditions it. It is the 'black gold' of the gardening world, particularly for the ever-increasing numbers of gardeners who want to steer clear of chemical fertilisers.
For millennia there was a closed system between man, animal and new growth. Man raised animals for food and clothing, collected the dung and worked it into the soil to feed and nourish edible plants.
Manure can return 70% of the nitrogen, 75% of the phosphorus and 80% of the potash that was taken from the soil to feed the animals. This is not a bad return when you consider that a single cow produces 13,000kg of manure each year. Until the invention of chemical fertilisers and the development of monocultural agriculture and horticulture2, this system dominated man's method of growing food.
The system is, of course, based upon Nature. Just look into a natural woodland and you'll see the same system in action. Plants flourish, taking nutrients and trace minerals from the soil. When the plant dies naturally, material is returned to the woodland floor, where it mixes with animal waste, is eaten by earthworms and used to feed the next generation of plant life. If the plant is eaten by an animal, the resulting dung is distributed across the woodland floor and the cycle starts again.
Manure In The Garden
Manure contains a wide range of minerals and nutrients, including abundant amounts of the three main chemicals that plants need for growth: nitrogen, phosphorus and potassium. It also contains many trace elements.
It also improves the structure of soil. It contains both animal waste and plant material (such as straw or hay). In other words 'humus' which enables the soil to hold moisture and promote easier, healthier plant root growth.
It is wrong to think that all manures are the same. The diet of every animal differs, especially between grazers and carnivores. Almost all of the manures used by gardeners are from vegetarian animals, such as horses and cows. But even these differ. For example, horse manure tends to contain undigested seeds eaten with grasses and gardeners using this manure often experience weedy gardens. Cows however have more effective digestive systems, which kill off the seeds and the resulting manure is less weedy.
In the UK, it is probably easier to get hold of (from local stables) than cow manure. It is quite easy to handle as it is relatively dry and usually mixed with straw or hay.
It is available in large quantities in the spring when cows are turned out and the winter yards are cleared. It is a good soil improver and contains high levels of nutrients. It is quite wet to handle.
This has a very high nutrient content, although it is wetter still than cow manure and therefore harder to handle.
Because sheep are not housed inside, collecting their manure is a labour-intensive job. It has to be collected by hand from the fields. It is also very high in nutrients, but because it is in the fields and not mixed with straw or hay, not so good for soil conditioning.
Chicken and Turkey Manures
This is powerful stuff, so it should not be used neat. It has a very high nitrogen content thanks to the fact that poultry eliminate their urine with their faeces. But if it is mixed with straw or hay and composted for a year or so, it is excellent manure.
It is alleged that this is the best manure ever. However, collecting sufficient quantities for a garden would be a challenge.
Seabird and Bat Guano
Seabird and bat guano are reputedly the bees' knees of the natural fertiliser world.
If you live close to a zoo, or if a circus comes to town, it is worth asking about their 'waste problem'. Elephant manure is highly prized by gardeners, both for its quality and quantity. And it will often be delivered by the trailer-load, free of charge.
How Much and When?
Never place fresh manure directly around plants as it can cause scorching of stems and leaves due to very high nitrogen levels. It is better to compost fresh manure for a few months to allow the nitrogen to dissipate and then use it, or obtain well-rotted manure for immediate use.
Well-rotted manure does not smell of anything more pungent than sweet earthiness and it tends to be dark brown, even black. You should not be able to distinguish individual pieces of straw or hay as it will all be rotted down. The length of the process depends upon the air temperature, the time of year (faster in summer) and the size of the manure heap. The bigger the heap, the hotter it will get inside and therefore the faster the manure will decompose. Generally, manure should be piled for at least 6 months before use. If it is mixed with wood shavings, leave it for a year as these take longer to break down.
Well-rotted manure should be spread and then forked into open beds in the spring, three weeks or more before planting.
As a rule of thumb, cow, horse and pig manure should be spread over the soil at an average depth of at least 3cm and then forked in; poultry and sheep manure - at least 2cm deep; rabbit, goat and exotics - at least 4cm deep.
When you dig a hole for a 'hungry' plant, such as a rose or a marrow, mix a spadeful of rotted manure with the soil in the base of the hole, so that the plant's roots can access all the nutrients straightaway.
If you are putting manure around existing plants, apply it to the local area and water it hard, to enable the nutrients to start feeding down to the roots. This is known as 'top dressing'. The most effective time of year to top dress is in the spring, as the plant begins to grow, but it can be done any time during the growing season if the plant requires a boost.
Another excellent way to use manure is to brew 'manure tea' to use as a liquid fertiliser. Put a handful of manure into a bucket of water for a couple of weeks. Dilute the resulting liquid, so that it looks like weak tea. Strain it through an old pillowcase and pour it over the plants you wish to fertilise using a watering can. You thereby feed the leaves, as well as the roots beneath, although this should be a supplement to, and not instead of, well-manured soil. This should be done once plants are established, in the summer and is particularly useful for fruit-bearing annual vegetables, such as capsicums, tomatoes and aubergines, all of which are heavy feeders.
The most common source of manure is the local stables. Unless they have an agreement with a local horticultural business, they are likely to have more than they know what to do with. Often stables will allow you to have it for free, as long as you cart it away. Private arrangements are common and many vegetable gardeners collect regular loads of manure in exchange for a box of produce each time they cart.
Many allotment societies have arrangements with stables or farms and get several trailer-loads of manure delivered in the spring, which allotment holders can then use.
Look out for advertisements in local papers and shops. You may have to pay a little if manure is bagged and delivered to your door. But if you really don't want to spend anything and don't have a stables handy, the circus or the zoo is the best option.
The Proof of the Pudding...
If you grow your garden in well-rotted manure, you will have fertile soil, which supports strong, vigorous and healthy plants. If those plants are edible, the food will taste as nature intended, not as designed by the supermarket buyers.
Go on. Give it a go.