Poultry manure benefits in the garden

Ever since I was a kid growing vegetables I would dig out manure from the chicken house and add it to the vegetable garden.  Poultry manure and sheep manure were the only fertiliser I had access to back then, and they seemed to do the job.  

Even when I was young I knew (from experience) that if I used poultry manure straight away it would burn plants.  Instead, I would dig it into the garden, and let it sit over winter to do whatever it needed to do.  When the weather had warmed enough that I could plant out summer crops the poultry manure had aged enough not to cause any damage.  It worked well and I did this for years.  

I few years ago I bought some soil to top up a few raised garden beds.  This new soil is dreadful.  One of its many issues is that plants growing in it show obvious signs of nutrient deficiencies.   

Poultry manure is great fertiliser

These days I probably could buy fertiliser if I wanted to, but I don’t want to.  I grow everything organically.  To increase soil fertility I still use poultry manure from my chickens, I also use home made compost, vermicompost, and green manure.  

I have a few chickens and clean out the chicken house from time to time.  I added their manure to the soil to age over winter.  I wondered if poultry manure would be enough to fix the nutrient deficiency in my soil, or if I also need to add something else.  

I used to know a few soil scientists who I would love to talk to about this topic, sadly I have lost contact with them so have to work out this problem by myself.  I don’t remember what nutrients are in poultry manure, or if it is missing anything important for plant growth, so I did some research.  I figured this may be helpful to someone else so decided to put it in this blog post.  

Poultry turn weeds and insects into fertiliser

 
The thirteen essential nutrients for plants growth are nitrogen (N), phosphorous (P), potassium (K), calcium (Ca), magnesium (Mg), sulphur (S), manganese (Mn), copper (Cu), zinc (Zn), chlorine (Cl), boron (B), iron (Fe), and molybdenum (Mo).  According to everything I read, poultry manure contains all 13 of these main nutrients needed by plants.  Poultry manure contains roughly 3-5% nitrogen, 1.5-3.5% phosphorus, 1.5-3% potassium, and a considerable amount of each of the micronutrients.  This means that mixing poultry manure through the soil should add everything that is missing in amounts that are worthwhile.  Adding poultry manure should go a long way to fixing any nutrient deficiencies of my soil.  

Some nutrients may be present in the soil in good amounts, but are not available if the pH is too high or too low.  The soil in my raised garden beds is currently a bit too high.  The pH of poultry manure is usually 6-7.  Adding poultry manure certainly won't correct my pH problem, but also won't make it any worse.  

 

Even these cuties produce a lot of waste

When I clean out my chicken house, I am not just scooping pure manure.  What I am digging out is probably better called 'chicken litter'.  Chicken litter contains feathers and straw and things that are mixed in with the manure.  This not only provides essential macro and micronutrients, it is also rich in carbon.  All of this is good for soil health.  

Nitrogen comes in a few forms, and this is important to know.  The 'inorganic forms' of nitrogen (ammonium and nitrate) can be immediately used by plants, while 'organic forms' of nitrogen (I am using the scientific definition of an ‘organic compound’) must be mineralized (converted in form by soil bacteria) before it is available to plants.  Don't be confused by this, I am not talking about farming organically vs using synthetic fertilisers, I am talking about organic compounds and their need to be mineralised prior to being available to plants.  

From what I read it appears that most of the nitrogen in poultry litter is in an organic form (about 89%), but poultry litter also contains ammonium (about 9%) and a small amount of nitrate (about 2%).  Poultry litter contains 3-5% nitrogen, of which about 11% is immediately available to plants, while the rest is slowly converted to usable forms by soil bacteria.  This nitrogen becomes available to plants as they need it throughout the growing season.  This is all good for my soil.  

As well as adding all the nutrients required for plant growth, adding poultry manure to the soil generally tends to attract earthworms and other soil life.  I grow everything organically, and try to encourage some of this soil life.  These soil dwelling critters seem to make the soil better in a number of ways.  

Based my research (and from years of personal experience), it appears that poultry manure/chicken litter is excellent to use in the vegetable garden as long as it is properly aged.  Poultry manure works well as a quick acting fertiliser, a slow release fertiliser, it improves soil structure, and increases soil health.  

I have a few chickens.  As well as laying cheap and nutritious eggs, eating food scraps, disposing of pests, and being happy little friends for my kids, my chickens are producing manure every single day.  I may as well use this manure for something good.