We all know that using manure in the garden is a great way to improve the soil and provide nutrients to plants. But why is this? What is the best type? How much of the stuff should I be using? Does poo stick to your fur?
First things first, no matter what type of manure that you are using, make sure that it has been aged, fresh manure can burn plants and may contain high levels of salt, weed seeds and other nasties that you don’t want to let loose in the garden. Fortunately all the manures that we sell at BAAG are aged and ready to go, how convenient.
Manures in general don’t have much in the way of nutrients to directly feed your plants. They are soil conditioners rather than fertilisers, your average synthetic fertiliser contains about 10 times the amount of nutrients. As a soil conditioner they help to unlock nutrients and feed the soil itself, help improve water holding capacity, plant nutrient uptake and soil structure. All of these things are critical if you want to keep your plants (and soil microbes) healthy and happy.
Which manure is best for you?
The best type of manure to use depends on what you want to do with it. The main types available are cow, sheep and chicken.
Nitrogen in cow and sheep manure is released more slowly than in chook manure. In cow and sheep manure about half the available N is released in the first year, the remaining half is released in the second year (as the N compounds are eventually converted into the nitrates which are available for root uptake –the slower release of N qualifies as a ‘good thing’ because it helps reduce leaching and extends N availability). Thus you need a lot of cow and sheep manure when initially preparing your ornamental or vegetable bed to make sufficient N available for the plants. However, this feature provides for more continued nitrogen availability in succeeding years, allowing for progressively lower annual application rates to meet plant requirements.
Chook manure commonly has the highest nutrient content because of the intensive nature of their diet. The higher nitrogen and phosphorus levels in chook manure make it ideal for vegie gardens and lawns but not so good for phosphorus sensitive native plants. You use less chook manure because it has about twice the amount of Nitrogen compared to cow and sheep manure and 90% of it is available to plants in the first year. The faster nitrogen-release from chook manure requires more constant but lower annual application to maintain nitrogen availability.
Good poo and bad poo
Avoid dog and cat poo… any poo that comes from an animal that eats meat really. The poo from these animals contains bacteria that you dont want to be playing around. They can make you very sick. Avoid manures from animals that have recently been wormed. This is generally more of a risk when using manure collected directly from stables and feedlots and then used directly on the garden or in worm farms.
Human poo on the garden is just plain wrong.
Fresh manures, especially from horses are likely to contain a large number of viable seeds. Aging or composting the manure helps to reduce the viability of almost all weed seeds. If you want to age manures, you will need to leave them in a pile for at least six months and turn them every once in a while. You can add straw or leaves to reduce the time and you will end up with a really nice compost, but it will reduce the overall concentration of nutrients in your pile.
How much manure should I use?
If using cow or sheep the general guide is about 25 litres per square metre, so about 1 cubic metre of manure will cover about 40 square metres of garden bed. After the first year of application you can use about half this amount. When using chicken manure dig in about 5 litres per square metre each year. Make sure that you dig it into the soil as much as possible when applying. Digging it in around a spade’s depth will give you the best results. In established gardens, work it through the soil as much as possible. Even if it is only into the top few centimetres is better than not at all.