My New Garden

This year I went to a little gardening class that our Relief Society arranged.  I got really enthusiastic about doing a "square foot garden" and - guess what - Rob wanted to make my dream come true!  Lucky me, huh? 

My dad ground up charcoal into a fine powder, then mixed it with some other stuff and then mixed it in with the soil.  Even though he has explained it to me several different times and I read an article about it, I can't get all the technical details down enough to explain it to other people.  The point is this: the plants grow better and the soil is much stronger in following years. The technical details, as written by my dad, are at the end of this posting.

Clockwise: 2 kinds of Lettuce, Onions, Cantaloupe, Cucumbers and you can barely see the Strawberries and Peppers.  The Marigolds are supposed to help keep some kinds of bugs away.  Plus, they add color.

Clockwise: Tomatoes, Peppers, Strawberries, Carrots

This year I learned how to grow lettuce!  Romaine apparently keeps growing back.  You cut it off in the center, leaving some outer leaves, then the new lettuce grows in right where you cut off the first bunch.  And it starts growing back really fast, too.  Awesome, huh? 

This is Alex's gardening box.  He wanted a box all for himself, so Rob built him his own tiny little (12" x 12") box.  He's growing carrots. 

Our tomato plants are already growing tomatoes!  I'm so excited to have fresh tomatoes!!!

Terra Preta Soil

While reading a National Geographic article two or three years ago about the depletion of soils around the world I learned of a particular type of soil, found along the banks of the Amazon river, that appears to be the best soil in the world.  It is called "Terra preta de índio" in Portugese and goes by the shortened term "Terra Preta" in English speaking countries.  After many years of scientific investigation into the origins of this soil scientists came to the conclusion that it is man made, using a process of "slash and char" (NOT "slash and burn") that loads the soil with high concentrations of charcoal. 

Charcoal is the key ingredient in terra preta soil that make is so effective for growing plants.  For most of my life I assumed that jungle soils were very rich soils since they appear to support such massive plant life.  While studying terra preta soils I learned that I was wrong about that.  Most jungle soils are very poor soils because the high volume of rain in the rain forests simply washes the nutrients out of the soil and sends them down the river to the ocean.  Terra preta soils, however, hold onto the nutrients and prevent them from being washed away.

Charcaol is used in industrialized societies as a filtration material that is capable of capturing all kinds of toxins and aromatic hydrocarbons and holding them within the carbon structure until they can be disposed of.  Charcoal is the key ingredient in filters used on kitchen range hoods that capture smoke and odors produced while cooking.

In terra preta soils, charcoal captures all the nutrients that plants need to grow big and strong and holds them there in the soil where they will be available when the plant's roots reach them.  In terra preta soils, along the banks of the Amazon, the charcoal can absorb the nutrients flowing down the Amazon during spring flooding and hold them there throughout the normal crop growing season where they are available to the plants that the native people plant.  The charcoal is not used up in this process, but it simply acts as a buffering storage medium to capture, hold and release nutrients as they are needed by the plants growing in the soil.

As scientists studied how terra preta soils work they discovered that charcoal alone will not enhance the soil's ability to provide nutrients to plants because charcoal alone captures the nutrients and then holds them and will not give them up to the bare plant roots.  Another symbiotic life form is needed to work with the plant to withdraw nutrients from the charcoal "nutrient bank".  Fungi, working in a symbiotic relationship with the plant roots (a mycorrhizal relationship) can pull the nutrients from the charcoal and make it available to the plant.  (See http://en.wikipedia.org/wiki/Mycorrhiza for a description of this process/relationship.)

In Natalie's garden we added 2 bags of Cowboy brand charcoal, purchased at Lowe's after breaking it into small pieces and processing it through a wheat grinder to create very small particles of charcoal that we thoroughly mixed into the soil so it would be finely dispersed throughout the soil.  (If you choose to add charcoal to your garden, do not use normal charcoal briquets as a charcoal source since they contain additive binders that hold the charcoal in the briquet shape.  Use natural pieces of charcoal that are still shaped like the pieces of wood from which they were made.)

If you simply add ground charcoal to your garden it will suck up all the nutrients in your soil and not allow the plants you want to grow to use those nutrients - resulting in stunted plants that may not produce any fruit at all.  You must precharge the charcoal with nutrients so that it is already filled with nutrients when it is placed in your soil.  I used about two pounds of ammonium nitrate to precharge the charcoal we used in Natalie's garden.  In some parts of the world urine or urea is used to precharge the charcoal.  I used ammonium nitrate because it was what I had available at the time.  If I were buying fertilizer for this purpose I would use 16-16-16 fertilizer.

If you simply add charcoal to the soil without adding mychorrhizae it will also not produce the benefits you are seeking because the plant roots alone will not be able to access the nutrients held by the charcoal.  In Natalie's garden we made a "tea" using Sweet Earth brand organic root zone starter fertilizer mixed with 5 gallons of water and allowed it to sit for 24 hours before pouring it over our planting beds.  Any commercial product that contains added mycorrhizae will work to add the mycorrhizae you need.

The result, as you can see from pictures of Natalie's garden is lush, deep green growth that far surpasses the results of any other type of soil ammendment I have ever tried before.  Natalie's is the second garden I've tried this process in and the results have been identical both times - large tomato vines with an excessive amount of fruit growing on the vines.  In the past, whenever I  simply added ammonium nitrate to the soil in which tomatoes were planted without the charcoal and mychorrizae the result was massive vines but NO TOMATOES.  Creating Terra Preta conditions in the soil gives you massive vines that support the production of massive amounts of fruit.

The added charcoal also holds more water than normal soils will hold so you don't have to water quite as often and you do not have to fertilize at all during the growing season.  With most gardens, to get maximum yields, you have to refertilize the garden several times during the growing season and to get maximum yields you have to give the soil just the right amount of fertilizer at exactly the right time so the plants never starve for nutrients during their natural growing cycle.  With terra preta conditioned soils you don't have to do this because the charcoal will hold large quantiites of nutrients in the soil but those nutrients are not available to "burn" the young plants because those nutrients are not loose in the soil, they are tied up by the charcoal, waiting in place until the plant roots reach out to them as they grow.  When the plant roots reach them, they are instantly available to the plant as they are needed.  If your soil has excess nutrients in it that are not tied up by charcoal then, when you water the soil those nutrients are redispersed throughout the soil where they can be taken up by bits of charcoal that were previously emptied by the plant roots. This ongoing buffering action continually replenishes the "nutrient bank" held within the charcoal.  If you are using secondary water to water your garden instead of cullinary water, then that water very likely contains many nutrients that were washed down into the acquifer or reservoir where the water is stored and those nutrients, dissolved in the water, are available to be stored by the charcoal rather than simply washing them through the soil each time you water.

True terra preta soils are self replenishing . . . they do not break down and they do not have to be constantly replenished with commercial fertilizers.  In the Amazon basin, owners of terra preta soils periodically harvest and sell off the top layers of their soil and the soil actually grows more soil to replace the soil that was sold.  As the mychorrhizae die off they put more carbon back into the soil.  Terra preta soils get better and stronger each year, rather than being depleted like normal soils are depleted.  I don't have enough experience yet with the creation of terra preta soil here in Utah to know when it will be fully self replenishing so I'll continue to add some commercial fertilizer to the soil in the fall of the year for the next few years, after the harvest is over, so that I know the charcoal will be fully replenished with nutrients during the winter.

Here are some helpful links to read about Terra Preta and the production of Biochar (various forms of charcoal used to create terra preta soils):

http://www.sciencedaily.com/releases/2006/03/060301090431.htm

http://en.wikipedia.org/wiki/Terra_preta

http://www.css.cornell.edu/faculty/lehmann/research/terra%20preta/terrapretamain.html

http://www.css.cornell.edu/faculty/lehmann/research/terra%20preta/Flyer%20terra%20preta%20landuse%20strategy.pdf

http://biochar.pbworks.com/FrontPage  (Terra preta and Biochar FAQ page)

http://terrapreta.bioenergylists.org/

http://132.180.112.26/bodenkunde/terra_preta/

http://www.opednews.com/articles/Making-Terra-Preta-Soil-R-by-Ramona-Byron-080821-153.html

Hundreds of sites are available to study Terra Preta soils and other people's experiences with them.  Just Google "terra preta".