El proyecto de café de residuo cero

Vermicompostaje con pulpa de café. Una charla con María Rodríguez, BYOEARTH, Guatemala.

In early July, Mariamawit Solomon (Technoserve/Ethiopia) and I had the opportunity to have a virtual conversation with Maria Rodriguez. Maria has been running vermicomposting in Quetzaltenango, one of the "strongholds" of Guatemalan coffee cultivation, for 15 years. During this very pleasant and informative conversation, one thing became clear right away: Maria does not do vermicomposting, she lives it. She loves her worms, and because of her success, one could almost believe that the worms love her too.

What made it so interesting for us to talk to Maria is the fact that the worms are almost exclusively fed coffee pulp. Only when there is a shortage of pulp, usually just before a new harvest, does she buy other organic waste or cow manure. In the early days, she also experimented with urban organic waste, but very quickly abandoned it. It was impossible to separate uncooked vegetable waste from cooked food scraps with all their meat, fish and bone residues. "It was just a big mess!" she said. Since this "adventure", she has concentrated completely on coffee pulp as feed - and is highly satisfied with it.

Maria primarily processes the pulp from her parents' coffee farm. In addition, she trains not only coffee farmers in the area, but also far beyond. Her mission as a social entrepreneur is to enable farmers to produce their own fertilizer from the pulp of the coffee processing instead of having to buy it at high prices.

Early days

It all started when Maria, at the age of 21 first heard about vermicomposting from one of her teachers in connection with the transformation of organic waste. She was very impressed, especially because vermicomposting was still quite new in Guatemala at that time. The red wiggler worm had been introduced in Guatemala only a few years before; the worms were seen as one of the possible solutions to at least partially manage the uncontrollably growing mountains of organic waste. At the same time, she saw the possibility that vermiculture could be a new or additional source of income for her as well as for others. Maria did not hesitate for long and soon after she founded her social enterprise "Byoearth".

Maria Rodriguez (middle) with community vermicomposting members in Sumpango, Sacatepequez, Guatemala

The right feed and the right worms

As the child of a third generation coffee farmer family, it was natural to consider the most important by-product of coffee production in terms of volume and weight, the pulp, as a food source for her worms. Since she does not need to sort the pulp, it is a much easier feed source to handle compared to the problematic urban organic waste.

When using the coffee pulp, Maria says it is important to let it sit and pre-compost for a few days. This makes it easier for the worms to ingest the pulp. Therefore, on Maria's farm, as is often the case with coffee producers, the pulp is simply left somewhere for an extended period of time. The degree of rotting increases continuously; it may not look pretty, but the worms are happy. This practice provides feed almost all year round. The only downside of this method is that the decomposition process of the pulp releases greenhouse gases, but much less than unused pulp. Also vermicomposting is not completely free of GHG emissions, but since it is an aerobic process, no methane is released, unlike in classical composting.

Maria feeds her worms every two weeks. A single worm produces about 1 gram of humus-like fertilizer per day (note: for the sake of simplicity, I will call this fertilizer-like fertilizer simply fertilizer in the following). So a lot of worms are needed to get an economically valuable amount of fertilizer. However, the worms take care of this themselves due to their high reproduction rate of up to 1000 eggs per worm annually. Worms are hermaphrodites, i.e. they have both male and female sex organs. As a result, each individual worm produces offspring. Each worm produces a capsule, which will hatch after about 20 days. Reproduction, however, is sexual; nature has not considered self-fertilisation.

For vermicomposting in general, so-called epigeic (Greek for "upon the earth") worms are used. These worms live on the surface of the soil and live on decaying organic matter. The most commonly used worm is the red wiggler (Eisenia fetida), also known as the earthworm, composting worm, Californian red worm and in Guatemala known as “Coqueta Roja”.

These worms are highly efficient "transformers" of organic matter: 40-60% of 100kg of biomass is converted into fertilizer. The rest is used for the growth of the worms and is lost as moisture and a small amount of CO2. Nothing will be left behind. Energy is not needed and the worms do not need to be paid for their work. The investment costs are close to zero (worms feel at home in all kinds of containers, from old barrels and tubs to brick or wooden plank beds), and the rather light physical work with the worms is not labour-intensive either. Only in large-scale production can the handling of fertilizer be physically demanding.

A look at the nutrients of a vermicompost based only on coffee pulp as feed shows us that it is a highly valuable fertilizer: nitrogen, calcium, phosphorus, magnesium, boron, potassium, iron, copper, manganese, zinc; and the list is not complete! The average pH is about 7.2.

An interesting and important aspect is that the worms obviously can break down the caffeine that's in the coffee pulp. All the laboratory tests she has had done so far have shown no traces of caffeine. Unfortunately, I could not find any further information about this ability of the worms.

Some business aspects

The fertilizer that is sold is finally packed in polyethylene bags. These bags are good to pack 100 pounds. They have very small holes that let the fertilizer “breathe” and preserve at the same time its humidity at adequate levels. The costs per bag are momentarily $0.50US for a new one, and $0.15US for a used one.

Asked about the biggest expense item, Maria answered: the transport costs to the customer! And since these are not incurred when the fertilizer is used by the farmers themselves, vermicomposting is a worthwhile business, especially for coffee farmers: with comparatively little effort and both little investment and low operational costs, high-quality fertilizer can be produced. The coffee trees will be grateful!

However, I did not mention one particular cost: the worms! If you buy 1 kg of red wigglers in Guatemala, you currently pay $20.00US. In countries where the worm does not occur naturally and you cannot pull your "starter worms" out of the ground yourself, this initial investment is unavoidable. But this initial capital is always worthwhile because of the worms' reproductive capacity. In addition, after some time, surplus worms can be sold. This is also for Maria an additional source of income. Before we spoke, Mario told me that she just sold worms to a nearby sugar cane and a cocoa plant.

So far, Maria has not needed to do any marketing. The word-of-mouth promotion works very well, so there are no costs for her in this respect. She only uses Instagram (@byoearth_gt) and Facebook to engage with customers and get some orders.

A 100lb bag of fertilizer currently brings her $12.00. But she does not only sell her own fertilizer. In the meantime, she has joined forces with two other vermicomposters in different regions of Guatemala and sells their fertilizer as well.

A driving force

Maria Rodriguez is a driving force in the spread of vermicomposting. Thanks to her and her "love for the worms" she hopes that more and more coffee farmers and farmers/producers of other agricultural products in Guatemala will convert their by-products into valuable fertilizers. She is always open to enquiries from interested people from all over the world.

Last but not least: one of her heartfelt passions is the support of groups of women that want to become producers and use vermicomposting as a force to empower themselves and their families. Improving their soil conditions and the food they eat will make them stronger - in many different ways!

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