Before you consider making your own organic fertilizers, you need to know why they are beneficial for your garden. So what are organic fertilizers and what do they do? Basically an organic fertilizer makes soil more fertile – richer in nutrients, more able to hold water and hence to effectively sustain the growth of plants.
The use of fertilizer is especially advantageous in the cultivation of vegetables, which require many nutrients for active growth.
Organic Animal Fertilizers
Naturally occurring animal manure, or faeces, is a basic form of organic fertilizer. Farm yard manure is usually mixed with straw bedding. Animal slurry is liquid manure, sourced from more intensive live stock farming that uses concrete and slats.
Animal manures all have different properties – for example, sheep dung is high in potash and nitrogen, or chicken litter is a concentrated source of protein and nitrogen. All animal manures need to age before they can be used on the garden or vegetable plot.
Manure improves the aggregation, or structure of the soil. It bulks it out and allows it to contain more water and nutrients, as well as encouraging microbial activity in the soil. Commercial organic animal manures are already well rotted.
If they are marked as ‘100% organic’ then they are precisely that. If the packaging contains words like ‘fortified’, ‘boosted’ or ‘organically based’ – then they are only partly organic. Depending on what else they contain, they may still be acceptable to the backyard organic gardener – for example, they may have added seaweed or minerals which are not certified organic, but which add to the nutrients in the soil. Always check the ingredients before you buy so you know you are happy with what you put on your garden.
Organic Vegetable Fertilizers
Vegetable compost is a good soil fertilizer, and if you compost your own organic vegetable scraps, you know where they came from – especially if you grew your own!
You can also make use of green manure, created by digging leguminous, or nitrogen fixing plants into the soil – clover for example. Their plant roots have nodes that contain Rhizobia bacteria, which fix nitrogen into the soil.
(See our article on making your own compost too!)
Simple Organic Fertilizers
There are various ways of making your own organic fertilizer, and some are much simpler than others. The main consideration is what nutrients you need to introduce to the soil. For magnesium loving crops – tomatoes, potatoes and peppers – simply adding a tablespoon of Epsom salts to a gallon of water will introduce sulphates as well as magnesium, and you can use this to water the plants once a month.
Ground egg shells introduced to the soil between crops will raise PH levels, and can be used in the same way as you would use garden lime. If coarsely ground and sprinkled on the soil around vulnerable plants, they can also (well so they say!) dissuade slugs and snails. Apparently they don’t like the ‘gritty’ feel on their bodies, although frankly, I think I have some kind of variety of super slugs in my garden, though I do live in famously rainy Manchester, England! (Editor’s note: apparently slugs can sometimes go under the soil and so avoid the egg shells. Not so snails though.)
If you’re not convinced about the slugs, ground egg shells also introduce calcium carbonate to the soil – and it is easy to grind them up in a blender. Fire place ash is also rich in calcium carbonate, as well as phosphorus. Sprinkle on your soil – though do not do this if it is very alkaline, and avoid using it on acid loving plants. If you keep fish, aquarium water is a useful and very handy liquid plant fertilizer, as it is rich in nitrogen.
How to Make Liquid Organic Fertilizer
Liquid fertilizers are very versatile. They can be applied to the plant leaves as well as to the soil, and they can help to break up compacted soil. Foliar application of fertilizer is a very quick way to get goodness to the plants. Regular compost, like aged manure or rotted vegetable scraps take longer to fertilize the soil. Liquid fertilizer is easy to apply with a watering can, or a hose.
If you soak a bag of organic animal manure in water for several days, you produce a cheap and simple liquid fertilizer. It is considered best to compost it first as fresh manure can carry bacteria like E coli, though I’ve heard of people who just soak the fresh manure for several days and get on with it! Personally, if I was using animal liquid fertilizer on my vegetable plot, I would prefer to use aged manure.
Vegetable Based Liquid Fertilizer
To make a vegetable based organic liquid fertilizer, you can use various ingredients. Green plant material – especially comfrey, clover and alfalfa, which are nitrogen fixing plants – can be chopped up, together with vegetable peels and scraps, egg shells, coffee grounds, grass clippings. A quick and convenient recipe for liquid fertilizer is to chop up a cabbage head, and put it together with ground egg shells and some grass clippings.
If you want the mix to be ready more quickly, you can bake the egg shells at about 300 degrees F for ten minutes, then place in a food mixer to turn into a powder – the heat will make the egg shells more easy to break up, and more easily degradable. Also some say there is no remaining egg ‘matter’ to attract rats, though if the eggs are in a sealed bucket this shouldn’t be a problem.
Place the mixture into a large (about 5 gallon) bucket, with a lid. Put in the vegetable matter, up to about half way, then fill three quarters full with water. Every other day, stir up the stuff in the bucket to introduce oxygen. The fertilizer will ‘brew’, and in about two or three weeks it will be ready for use. Diluted ( x 2 or more, if you prefer), it will be a great liquid spray for plant foliage, or use it fresh round the roots of plants.
I’ve sometimes read you need to put the bucket in a cool, dark area, but then a fellow allotment owner swears by a sunny spot! Unless the bucket is transparent, the sun could only provide heat, which may make for a quicker job, but it’s up to you. I suggest you trust to trial and error – just leave it outside, stir it every second day and let it do its thing!
Editor’s Note: Look out for Eileen’s next article on how to make Compost Tea. I want to make a little joke here about making yourself a cuppa – and one for the garden – but I’m just going to leave that right alone I think 🙂