Organic fertilisers: how manure and other goodies can help your vegetable garden
The most important difference between organic and chemical fertilisers
is easy to remember: organic feeds the soil through slow release, chemicals
feed the plants directly with an immediate injection. In our first feature
we already cover why organic is better. Organic
growing improves the soil, encourages earthworms and good bacteria, which
give your plants a natural boost. Chemicals can kill these earthworms
and good bacteria.
Now Please tell me what I need to Know
So instead of grabbing chemical fertilisers in a box why not follow the
ways of many successful gardeners and go organic. Fertilisers are normally
expressed by their NPK rating. This is the ratio of nitrogen (N), phosphorus
(P) and potassium (K) - all vital ingredients in a rich soil.
Put simply nitrogen makes all the green stuff grow like crazy. Phosphorus
makes the roots strong and gives flowering a boost. And potassium keeps
the juice pumping through the plant, helps your plants during difficult
times (very low or high temperatures, lack of water and during disease)
and gives fruit and seed production a push along. They're all critical
to healthy plants.
Also of importance is calcium which prevents new growth from dying and
a swag of problems. Sulfur is also important in keeping growth going.
Then there are the micronutrients. All those small quantities of other
nutrients which maintains plant health. Fortunately mother nature (sometimes
with a little processing help by mankind) has all these elements in abundance
so you can give your soil a boost.
One thing to always remember when handling manures, soil or any organic
matter is to always wear tough gloves to protect you from bacteria getting
into any cuts.
Manures
Matured animal manure is one of the most important things an organic
gardener can get their hands on (while wearing gloves of course!) Manures
are generally good all rounders having a fair amount of nitrogen and a
little bit of everything else, including very small amounts of micronutrients.
You should be able to easily buy bags of aged manure from your local nursery.
Mature manure has had time to rot down a little, losing its volatility
which can "burn" plants. If you have access to fresh manure
make sure it "cools" down. Pile it up and let it rot down for
6-8 weeks, making sure it's covered to keep flies away and to stop rain
leaching the nutrients out. You can also add it to your compost heap.
The next big question is what manures are better for your garden? This
varies depending on what you want to achieve. Chicken manure (fresh or
in processed pellets) is very high in nitrogen. Plants boom with chook
manure (maybe they're trying to grow away from the smell?) But chicken
manure is lacking in almost all other nutrients. The rest of the stable
(literally) is more balanced. Sheep, cow and horse manure are well rounded
fertilisers which will help boost the organic content of your soil.
Compost
Compost is fantastic. Rich in NPK and packed with micronutrients and
micro-organisms it is a must. Problem is you can rarely buy it in a bag
from the nursery although this is changing. You generally have to make
your own. Making compost is an important enough topic to have its own
feature. We'll aim to write it over the next month.
Mushroom compost
This you can easily buy in a bag. It's a bit of a mix between compost
and manure. Afterall, it's just horse manure which has rotted down and
had mushrooms grown in it. It doesn't have as many nutrients though as
most organic fertilisers. But it's great for bulking up the organic content
of the soil. A good use for mushroom compost is when you start making
your vegetable patch. The root crop and onion bed doesn't like a lot of
nitrogen, but needs organic matter. For this bed mushroom compost is very
handy.
Blood meal
This is packed with nitrogen. Every wonder where the cows go after they've
made the steaks? Now you know. It's fantastic for promoting green growth
and micro-organisms in the soil love it. In Australia you won't find blood
meal as a distinct product. It's usually packaged with bone meal and marketed
as blood and bone - and it's the best stuff you can get!
Fish meal
Now take the cow analogy and apply it to fish. Fish meal is a great nitrogen-phosphorus
all rounder with a lot more N and P than manures. It's higher in phosphorus
than blood meal as it includes crushed and processed fish bones.
Fish liquid fertilisers
Just like fish meal but in a liquid rather than a powdered form.
Bone meal
Blood meal's brother but packed with phosphorus instead of nitrogen.
The good part about bone meal is it breaks down quickly for faster use
by the plants.
Rock phosphate
This is nothing more than crushed rock high in phosphorus. Sprinkle it
around for a slow up take of phosphorus.
Sulphate of potash (or Sul-po-mag)
Sounds like a chemical fertiliser but it's not. This mineral product
has an incredible amount of potassium which is good news for fruiting
vegetables (eg tomatoes, peppers (capsicums and chillies) etc) and your
fruits (including melons and all fruit trees). Because it's so packed
with potassium you don't need huge qualities, just a nice sprinkle around
your plants (1 part to 10 parts of blood and bone meal will give you a
great all round fertiliser). It's also readily available which is very
handy when your fruits are forming. Sulphate of potash is also very high
in sulfur which keeps your plants healthy. In Australia, you can only
get suplhate of potash, not sul-po-mag so you'll miss out the magnesium
side of things (which you can get in dolomite...)
Lime
Normally when you think lime you think about increasing the pH level
of your soil. But it is also a handy source of calcium. If you can get
your hands on dolomite lime you'll also get an added boost of magnesium.
Gypsum
If you've already got a very alkaline soil and don't want to risk adding
lime try gypsum. It's not only a clay breaker it's also rich in calcium
and sulfur.
Liquid seaweed fertiliser
This is one of the best organic fertilisers you can get. It's made up
of lovely seaweed found in colder seaside climates, not the grassy trash
around here. It's fantastic not so much for NPK, but for the micronutrients
and trace elements not often found in most of the fertilisers above. We
use a capful of concentrated seaweed fertiliser with a litre of water
to dilute it. Sprayed onto the leaves early in the morning it is absorbed
to give a real boost. You can also give a bit of a spray at ground level
onto the mulch where it will eventually seep down to the roots. One fertiliser
you've got to have.
Liquid manure (compost
tea)
This is a real make your own organic fertiliser without much science
involved. Get a nappy bucket or small rubbish bin and fill it with water
(We find the nappy bucket is a lot more manageable). Then either mix in,
or put into a hession bag, all your organic goodies. We usually toss in
manure, a little compost, blood and bone meal, a capful of concentrated
seaweed fertiliser, add a few comfrey leaves and give it a good stir.
Put a lid on it to keep the smell in (because it does smell) and the flies
and mosquitos out. Around a week later we put 2 litres of the mix into
a 10 litre watering can and then add 8 litres of fresh water (1:4 ratio).
This dilutes the mix otherwise it's too strong. The ratio can sometimes
blow out to 1:6 as it is very potent at the bottom of the bucket. Then
we start pouring it into the soil around our vegetables and fruit trees.
Done every 2-3 weeks this helps keep your plants healthy.
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Two green manure crops: the background crop has just been dug
in, while the younger crop in the foreground is just getting started
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Green manure
During slow growing seasons you can boost the organic nature of your
soil by growing green manure. Sounds odd but green manure is just plants
that are dug into the soil to add organic matter and improve its quality.
One of the key ingredients in green manure are legumes which fix nitrogen
into the soil. To get the best nitrogen boost though you need to make
sure the seeds are inoculated with a special bacteria.
You normally sow green manure into a bed which has had its nutrients
sapped by a hungry earlier crop, like sweet corn, pumpkins, cucumbers
and melons. Till the soil before hand and toss around a mix of green manure
seeds. This is done early in winter in cold climates and early in summer
for very hot and humid climates. Then with a rake cover them a bit, water
and walk away. Around 2-3 months later you should have a lush knee high
mat covering the bed. Then all you have to do is dig it into the soil
where it breaks down over 1-2 months. Once you've done this the bed is
ready for the next crop and the soil is even better than when you started.
For cold climate winter green manure go for:
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Lupins
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Tic beans
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Oats
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Subclover
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Fenugreek
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Barley
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Woolly pod vetch
For humid and hot summer green manure go for:
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Cowpea
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Japanese millet
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Grey sun flower
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Buckwheat
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Lablab
Last updated
23 October, 2008
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