September Program Recap

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September Program Recap
Soil Amendments – Beyond Compost 
Presented by Tom Wilkinson, author

Tom Wilkinson was concerned that too much organic material was being sent to landfills. He began composting the organic material from his household waste and then improved his compost with red worms, creating a vermicomposting system. He sold his vermicompost at the local Farmer’s Market. Tom wrote his first illustrated book called Beyond Compost and later he became interested in biochar and added that to his vermicompost. This blend he named “BioPreta”. In 2013 he wrote the 2nd edition of his book called Beyond Compost +.

Tom gave us the background story of biochar. Spanish conquistadors in Peru about 50 years after the time of Columbus were sent on an expedition over the Andes and into the jungle led by Francisco de Orellana, along with Fr. Gaspar de Carvajal, a Spanish Dominican friar. They were looking for gold and cinnamon, a prized spice.

When the expedition reached the area where the Negro River meets the Amazon River they saw as Carvajal described: “large cities, well-developed roads, monumental construction, fortified towns, and dense populations.” Over the next 400 years, scholars thought that Fr. Carvajal’s report was unfounded. Later expeditions to the same area did not find evidence of that advanced civilization. The first expedition’s soldiers had exposed the indigenous people to diseases from which they could not survive. The jungle had taken over their wooden structures and gardens.

However, in the last fifty years, scientists have found proof that Dr. Carvajal’s writings were true. Archeologists have found evidence in Brazil, that there were thriving agricultural communities along the Amazon River. Rainforest soil is a very thin layer. Rain quickly drains right through it. They found that the ancient garden areas are still there with dark, rich, fertile, six-foot deep soils that were man-made. This soil is called Terra Preta del Indios, “dark soil of the Indians” Similar soils have been found in Africa.

Between 2500 to 9000 years ago people made these soils by combining highly-concentrated low-temperature charcoal (biochar) with composted organic waste, fish, feces, and animal bones. This mixture added to the soil layer produced as much as 880 times the grain crop yield than the unamended soils. Biochar does not disintegrate. It is “permanent soil restoration.”

Making charcoal is “baking biomass” (like wood) in the absence of oxygen. Tom explained that biocharringis putting carbon in the soil. Carbon in the soil provides a home for microbes in the soil. Plants do not take carbon from the soil. Plants putcarbon in the soil. Plants get carbon from the air. Carbon atoms that get into the soil stay there forever.

The rainforest has been intentionally set on fire for development. Slash and burn is not as effective as slash and char. Charcoal is not burned wood!
We learned that:
• “Slash and Burn” does not produce CARBON, except by accident.
• “Slash and Burn” produces mostly ashes.
• Ashes are not CARBON.
• CHARCOAL is CARBON produced on purpose by humans.
• Humans have made charcoal for thousands of years.

Tom suggests that the best size for a home composter is 3 ft. x 3 ft x 3ft. He starts by composting organic matter, then separates it with his VermiHarvesters. He then introduces red worms into the mix. Tom uses stacks of large plastic bread trays. The worms work their way through the compost spreading microorganisms and leaving behind their castings. Check out Tom’s book to learn how to build a Vemiculture System and a VermiHarvester.

A question was raised if worms can be left out in the compost all winter. Tom used to separate and bring the worms inside, but it was messy. He decided to try leaving them in the compost all Winter. He explained that Red Worms lay eggs the size of a grape seed in the Fall. Each egg contains 15-20 wormlets. In the Spring Tom found that all the adult worms had died, but he had so many more new young worms to replace them. Tom recommends purchasing Red Worms online from a reputable dealer—not from bait shops!

Tom kindly gave each of us a sample of his product, BioPreta. More information about BioPreta can be found at It is made by his method of composting a wide variety of ingredients. It is fed to worms that digest it and leave behind rich castings along with a wide variety of beneficial microorganisms. Then, the microorganisms are blended with finely graded hardwood biochar. The biochar remains in the soil attracting microbes and keeping them down at the root zone of plants. The website states: “Plant roots provide exudates to the microbes in exchange for nutrients in a natural balance as they need them.”

BioPreta can be used wet or dry. The BioPreta directions state that 1 cup of BioPreta can be mixed with 5 gallons of water. For best results, stir to add air for a week before using as liquid fertilizer. Alternately, one cup can be mixed with one cubic foot of organic potting mix (without synthetic chemical ingredients).

Tom ended his presentation saying that there is a new, promising use for biochar. It is starting to be used as fuel in countries like Haiti and Africa.

We thank Tom Wilkinson for sharing his knowledge of vermiculture and biochar with us. 

Information compiled by Ruth Oldenburg, WORC Communication Chair