April 2011

Composting

How to produce black gold to assure high soil fertility and a good crop yield

Arnold Brower
Director Huertos Educativos
Cochabamba


Once the crops are in place it is time to think of the future. The plants will be extracting nutrients and a continuous cycle of growing crops will eventually deplete the soil. Chemical fertilizer adds a rapid shot of nutrients, but also kills microorganisms and leaves you with an impoverished soil in the long run. You can buy organic fertilizer but you can easily make it yourself from material that is thrown away.

Compost is called black gold, because of its’ dark color and its’ high value for the garden and is made from organic matter piled in a heap. It is a natural product which not only provides nutrients, but gives structure to soil and helps improve soil life. A healthy soil contains all sorts of animals like worms who help aerate the soil. The trick with making good compost is using different layers of dry and green material mixed together as dry material has carbon in it, while green material contains the necessary nitrogen.

The best spot to build a compost heap is below a tree in a shady part of the garden. Begin by piling up branches and twigs cut into pieces of about 20cm; this layer will provide air. Then continue with a layer of 15cm dry material (leaves, grass, dried cutting flowers, etc.) cut up in small pieces. The next layer is green material (fruit and vegetable peels, garden weeds without seed, etc.), followed by a thin layer of compost, manure or dark soil in order to add soil life making sure that microorganisms can do their job consuming the organic matter. After this layer you lightly water the heap and continue with a second layer of fine dry material, followed by a green layer and then again the layer with the microorganisms. Once you’ve finished a heap (about 1 cubic meter) you wait for a week and then turn it, mixing all materials together; the heap should feel warm inside, if not it is too dry or too wet, in either case add water or dry material respectively.

Every week you turn the heap until it looks like a dark soil and smells of wet forest. Depending on the outside temperature, the material and the humidity and oxygen level you can produce compost in 2-6 months. A good way to make sure the compost is ready and not still cooking is by putting a bit of compost in a plastic bag and closing it. After 24 hours it should still smell of wet forest, if it smells rotten it is still being processed and you should be more patient.

What about Stevia?

The reason that Bolivia is facing this transition is that the prices of sugar in Bolivia are so low that sugar-producers, will gain economic benefits from selling the sugar abroad at elevated prices. According to online-newspaper Latin American Herald Tribune (LAHT) this made President Evo Morales to threaten the sugar producers who keep selling the sugar abroad with nationalization.

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