As I told you before, I’m a fan of organic gardening. Not only is fertilizer from organic sources a good additive to your soil than enhances its structure (especially for sandy soil!) but it’s also economically more viable than chemical fertilizer. Inorganic fertilizers only feed your plants and are often washed away, therefore wasting the environment.

Disadvantages of organic fertilizers are that they contain much less nutrients per weight unit (which makes them more expensive when it comes to transportation) and that they release their nutrients much slower than inorganic fertilizers.

From a chemical point of view, “organic” would be the counterpart to inorganic, which could for example be limestone. However, when I say “organic” I refer to substances not attained from chemical processing. I want to list the most important and handy forms of organic fertilizers in the following article.

Organic fertilizers

Manure: Besides being an umbrella term that also encompasses compost and so called “green manure”, manure means animal feces (from pig, cattle etc.) that may come in liquid or dried form. Manure generally improves soil structure. Its fertilizing value depends on the respective animals, f.e.:

• chicken litter is high in nitrogen and protein
• sheep manure is high in nitrogen and potash

You should, of course, consider the odor of manure from animal waste. One other important factor is its source – it may be contamined with antibiotics if the respective animals have been treated with antibiotics.

Seaweed: Seaweed supplies all three macro-nutrients (n-p-k) and amino acids; you can use seaweed as mulch or as a component of your compost heap. One potential problem is that it contains quite a lot of salt and may be harmful for worms in your compost heap. You should try (especially if you live near the coast) and observe the effects carefully. Seaweed may also be bought in processed form (dry and liquid).

Vermicompost: Vermicompost is a special form of compost that has gained popularity in recent years – it’s ordinary compost that has been thoroughly broken down by earthworms. It contains high amounts of nitrogen (which is a real bottleneck nutrient) than normal compost. You can process vermicompost in your own compost pile. See http://www.redwormcomposting.com/ for more info!

Guano: Due to its high levels of nitrogen and phosphorous, guano is a well liked organic fertilizer (plus it doesn’t smell as bad as other animal manure!). Pay attention to the fact that seabird guano is higher in nutrients than bat guano! Guano may also be applied to leaves as a fungicide.

Bloodmeal/bonemeal: Bloodmeal is high in nitrogen, bonemeal contains phosphorous in large amounts. This said, I personally don’t like to apply these both as I try to circumvent animal mass production. Ok, blood&bone-meal are only by-products, but they still add to the profits of animal farms.. You can, however, mix blood meal with water and use it as a liquid fertilizer for your plants. Bone meal is a real slow-release fertilizer that should best be mixed with the soil.

Peat: Peat (or turf) are partially decayed plants that have been trapped in moors; it may be used as fuel or by us gardeners. Peat increases soil acidity and improves its structure by storing nutrients (it does itself not contain important nutrients).

Cover crops: Cover crops are plants that are grown for some time and then mixed into the soil for structure and nutrients. Leguminous crops like peas or alfalfa are used most often, as they take nitrogen from the atmosphere and fix it into the soil, therefore guaranteeing a sustainable ecosystem. They’re also commonly used in conventional agriculture – but they’re not so convenient to use in your ordinary garden, as you would need to forgo planting of food crops for a certain time period. See my article on bio-intensive gardening for a method to circumvent this!

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