Chicken manure

Ah, chicken manure, that wonderful bi-product of poultry rearing. Chicken manure is a valuable and free resource, but using chicken manure in the garden is not a case of simply spreading fresh manure on the soil. It is important to understand the properties of the manure, and to age it or compost it before it is used.

Chicken manure is an excellent source of nitrogen – one of the three main nutrients essential for plant growth. It also has reasonable amounts of phosphorus and potassium and it also has smaller quantities of other plant nutrients – including calcium. When we talk about how good a manure or some other soil amendment is as a fertilizer, we tend to use a ratio known as NPK. This gives the percentage nitrogen, phosphorus and potassium content of the material.

Fresh chicken manure is very variable in its NPK values, since so much of it depends on the diet of the animals and conditions in which they were kept.

There are a number of reasons why it is not a good idea to spread the manure directly around your edible garden. Firstly, and most importantly, like other manures, chicken manure can contain bacteria and other pathogens. Some of these, like salmonella, can pose a serious threat to human health. It is therefore very important to wear gloves when handling the material, and to wash hands thoroughly if you do come into contact with it to avoid contamination.

Secondly, fresh chicken manure is also high enough in nitrogen that it can ‘burn’ plants, and may even kill them. The roots of a plant can be damaged if they come into contact with too much nitrogen.

Lastly, though it is lesser than the above concerns, there is the issue of smell. Fresh chicken manure can be rather pungent and it is certainly not something that you want in proximity to edible plants, nor in regularly tended areas.

Fortunately, it is very easy to compost chicken manure so that it is safe for people and plants and can be spread around your growing areas or used in other ways in your garden. The quickest way to compost chicken manure is using a hot composting system whereby you build a compost pile (in one go) that is at least one cubic metre in size. The chicken manure in the pile should heat to 60-65oC for at least 15 days. The higher temperatures in such systems mean that the material breaks down more quickly and pathogens usually die at these higher temperatures too. This significantly reduces the risk of contamination.

Alternatively, you can use a typical cold composting heap or bin. In this case, materials break down much more slowly. The manure is safe to use only after a much longer period such as one year.
Once the chicken manure is composted, you can use it as you would any other compost in your garden.

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• Gardening