Manuring Our
Allotments
This is a complex subject and doubtless large portions of
degrees on agriculture and horticulture are set around this subject. If you can get hold of a copy of a book, now
out of print – Know and Grow Vegetables –P.J.Salter;J.K.A. Bleasdale; and
others – from The National Vegetable Research Station, it is a unique,
interesting and comprehensive study of
many aspects of vegetable growing.
However, most plot holders just want to know which of the
manures available will give the best results on their plots.
It must be remembered that adding any organic manure will
contribute to the acidity of the soil due to the breakdown process of the
compost. But, for most plotholders on our heavy clay ground, adding organic
matter, no matter how poor in essential nutrients, helps to break down the
heavy structure of the soil and allows for freer drainage and greater nutrient
uptake – of course, it is more complicated than that.
As a simplification of the needs of plants – Nitrogen[N] is
used for leaf growth, Phosphorus[P] is for seed germination and root growth and
Potassium [K] for flowers and fruit.
Not all of our members are dedicated organic growers and
their choices must be respected though, continued addition of non-organic
fertilisers brings its own problems and there is an argument to suggest it is
not sustainable.
I have gained the following information from:
NPK Values of Animal Manures
|
|||
N Nitrogen %
|
P Phosphorus %
|
K Potassium
(Potash) % |
|
Cow
Manure
|
0.6
|
0.4
|
0.5
|
Horse
Manure
|
0.7
|
0.3
|
0.6
|
Pig
Manure
|
0.8
|
0.7
|
0.5
|
Chicken
Manure
|
1.1
|
0.8
|
0.5
|
Sheep
Manure
|
0.7
|
0.3
|
0.9
|
Rabbit Manure
|
2.4
|
1.4
|
0.6
|
Growers usually have a
preference for either cow of horse manure but, for the most part it does
depend on what is available and how much straw [or even hay] is mixed in. Of
course, the addition of the straw is very useful for improving the quality of
your soil, particularly in heavy clay. Resist the temptation to add fresh
manure to your ground – it too strong. At least pile it up, cover it with a
plastic sheet, a tarpaulin or an old carpet and leave it for a couple of
months – longer is preferable.
With
all poultry manure it is generally too strong to use directly on the garden
but it does make an excellent activator for a compost heap. There is little
bulk in poultry manure so using it as an activator makes most sense. The only
plant that you can apply it to directly is comfrey.
NPK Value of Home Made Compost
|
|||
N Nitrogen %
|
P Phosphorus %
|
K Potassium
(Potash) % |
|
Average Home Made Compost
|
0.5
|
0.27
|
0.81
|
NPK of Natural Fertilisers
N Nitrogen % P
Phosporus % K Potassium %
Bloodmeal 12
0 0
Bonemeal 3.5 18
0
Hoof & Horn 12 0 0
Fish, Blood & Bone 6 6 6
ChickenManurePellets 4 2.5 2.3
NPK - Liquid Comfrey – although
low, it is immediately available to plants
Having covered manures and compost, the next thing to look at is a
fertiliser you make yourself, comfrey tea. Following the recipe of 6 Kg (14lbs)
of wilted comfrey in 90 litres (20 gallons) of water in a barrel, produces a
liquid feed with these values
N
Nitrogen % P
Phosporus % K Potassium
%
Comfrey
0.014 0.0059 0.03440
That said, none of these tables shows
the availability of or the importance of the trace elements. And, how do we
ensure our plants have enough of these to assure excellent growth and crops.
I will put up more information on adding lime and trace elements on my next blog.
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