Dr. Curtis Swift

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October 25, 2012
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SWIFT: Biochar, good for the soil

Some things that happen at this time of year are natural such as the change in color of my asparagus plants. They are a uniform golden color. A week ago the asparagus ferns next to my lawn were yellow, while the ferns near the flower bed were still a healthy green. Now all of ferns have a golden hue.

As soon as they turn brown I'll cut them down and either add them to the compost pile or turn them into biochar. I've got quite a pile of dried plant debris in my back yard waiting to be burned into char. I've already turned some of this pile into charcoal and intend to burn the rest before the end of the winter. I'll mix this with manure or compost to charge it with nutrients and then work this black carbon material into my garden where it will increase the aeration and nutrient-holding capacity of my soil. While this may seem like a new concept, it was used by the people of Mesoamerica thousands of years ago to increase the fertility of the soil where they were growing crops.

I recently purchased a propane burner for my essential oil still so will use that to turn my plant debris into biochar. I could dig a big hole in my backyard, pile everything into the hole and set it afire but I think the local fire brigade might not like that. Even though the fire would be covered with soil to create a burn in a low oxygen atmosphere I still think the fire chief would not approve. So, I will be setting a barrel on my propane burner, putting plant debris in the barrel, putting on the cover, and turning on the burner. I'll poke a hole in the top of the barrel and burn the plant debris in the barrel using a process called pyrolysis.

I'm not sure how long it will take to complete the process so I'll base the burn time on the escape of gas from the hole in the barrel. If the process works properly the escaping gases will burn off. I might even have to light these escaping gases to start the process. This is the same process used to create charcoal briquettes so it should work in my back yard. If I had a way to capture the escaping gases I could use these gases to heat my home.

If you are leery about burning your own biochar, but want to take advantage of biochar in your garden, you could always buy bags of Cowboy Charcoal from your local True Value or Ace hardware store. A friend drives his Jeep over bags of this charcoal to break it down into smaller pieces before working it into his garden soil. Even bones can be turned into biochar. I wonder if Rib City would be willing to save those bones from their luscious ribs for me. I'll have to ask next time I stop in for some of their baby back ribs.

Teddy Hildebrandt of T4 Tree Services dropped by the other day to bring me some soil samples to send off for analysis. We talked for awhile and finally got around to the idea of this year's drought-increasing problems for our plants.

He mentioned he had treated more Austrian pine trees this year for the black pine leaf scale than in past years. This insect is known to develop high populations on trees that are stressed, especially from drought.

When you have 20-30 scale insects feeding on one needle you know there is a major problem with the health of that tree. As these insects feed they create openings through which diseases can invade, but the major problem is the reduction of photosynthetic tissue needed to maintain the health of the tree. As more tissue is damaged, less and less energy is available for the tree.

One advertisement for this tree states "very hardy, withstanding city or seaside conditions, heat and drought, and clay and alkaline soils." If you believed the advertisement, this tree is great in any situation and should do great in our dry semi-arid conditions. If the advertisement was correct, we would not be having trouble with our Austrian pines. Maintaining adequate soil moisture is obviously critical for the health of this tree, but so is maintaining the proper soil oxygen and nutrient levels. For that reason, Teddy offers his clients the opportunity to have the soil in which their trees are growing analyzed.

Thus far we have found that many trees are growing in soils lacking adequate organic matter. Organic matter helps keep the soil open so the roots can breathe and take in the water and nutrients needed by the tree. While treatments containing dinotefuran or imidacloprid are quite effective in killing the scale, steps need to be taken to determine what is causing the stress responsible for the insect being successful in its attack on the tree in the first place. A soil test helps determine some of those stresses.

As a follow-up on the effect of this summer's stress on plants, particularly native plants, I will be talking about this very issue at the visitor's center on the Colorado National Monument Saturday, Oct. 27. This free session will start at 3 p.m. and conclude at 4. If you want to learn more about plant stress and how it affects insect and disease problems, stop by and participate. Hopefully, I'll be available to answer many of the questions you have on how you can maintain the health of your plants.

Dr. Curtis E. Swift is a retired horticulture agent with the CSU Extension. Reach him at Curtis.Swift@alumni.colostate.edu or check out his blog at http://SwiftsGardeningBlog.blogspot.com. He owns Swift Horticultural Consulting and High Altitude Lavender.


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The Post Independent Updated Oct 25, 2012 01:25PM Published Oct 25, 2012 01:24PM Copyright 2012 The Post Independent. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.