Amending soil with Biochar. Discuss......

Last summer I attended a day course on improving soil for vegetable production, the course was held in the next village and the plot had even sandier soil that I have here.

We were taught the basics of soil fertility, the value of the soil microbiology and organic matter. Then moved into the value of inoculated Biochar in such circumstances for improving the possibilities of life, water and soluble nutrient retention and thus improving the growing conditions for everything in the soil.

I was already well down the track of improving the soil with compost and had several pallet bins filled with maturing compost that had already completed its hot stage by this time. My thoughts, post course, turned towards Terra Preta and I did some research. Many of the ‘recipes’ don’t include the original soil in any quality, but I believe this to be an important part of the mix, so have adapted several possible blends to suit what I feel will work the best for here.

Throughout the autumn I pruned, cleared and scavenged wood to make Biochar, I was surprised on a number of counts   - how easy it was to make, especially if all the materials were about the same size.   - how much I could process in a trench burn.  - how much water was needed to extinguish the fire and how easy it was to shred the damp Biochar with a shovel blade whilst digging it out of the hole.

I inoculated the char in a barrel of ‘soup’ ( diluted horse and goat manure, nettle tea, mares tales tea, urine, juice from fermented vegetables and anything else dubious I came across that might help) for a week and then folded it into each compost bin to absorb and grow for the winter.

I garden in fairly hot dry conditions and my plan is to convert a current growing bed into a much wider sunken bed to retain more moisture and reduce wind assisted evaporation a little.  

I have removed a sizeable volume of earth (all directly put to good use elsewhere) forming a trench alongside the current growing area and am now, in a vague style of double digging, demolishing the old bed, mixing in copious amounts of Biochar compost blend along with a barrow load of scoria every meter or so, filling the trench and lowering the final level of the soil by a few inches.

Roughly the make up is 40% top soil 45% compost 10% Biochar and 5% scoria  blended on site to a depth of 70cm

I’m hoping that it’s a long term investment, a huge undertaking for the sake of vegetable production, but if it lasts like I believe it will. I’ll be extremely happy in my old age.

I’ve scoured the Biochar threads and the soil threads here and haven’t come across any other posts explaining how it is used as a soil improver once it’s been inoculated and how it might be incorporated into a mature planted setting.

I’m looking forward to seeing your comments

Seems like you did good.  Wow 70 cm double digging.  I did that with my beds not as that deep maybe 24 inches.   Good work out.  Time will tell, see how things grow in it this coming summer.  It is always good up front to try to mix stuff in.

Sam Rellim wrote:

I’ve scoured the Biochar threads and the soil threads here and haven’t come across any other posts explaining how it is used as a soil improver once it’s been inoculated and how it might be incorporated into a mature planted setting.

I’m looking forward to seeing your comments

I, and I think many other people, simply pile the compost/biochar mix right on top of the ground around more mature areas, especially around trees and bushes.  Weather, worms, and other soil creatures can incorporate it for me at their pace.  I don't really incorporate anything into the soil after a create a new garden area, and many times, not even then.  I never incorporate anything into the planting hole when I'm putting in trees or bushes.  I plant directly in the native soil and add any amendments on top of the ground after planting.

I work the biochar into the soil or work biochar containing compost into the soil.

Biochar works better when it's in the soil than when it's just on top of the soil and with the heavy clay soil here I'm really not at convinced that no-dig is a viable methodology. The soil is so poor here that tillage doesn't do any significant damage and I believe that as long as you are adding significant amounts of biochar and/or compost while turning the soil then it does improve rather than degrade.

Of course tillage isn't a long term strategy and I only plan to do that till a certain area has improved enough. Also im not talking plouging up the whole land here, just small areas selected for the cultivation of annual vegetables

I also dig it in.  I slice down with a spade and pry open the soil to the depth of the spade (8-10 inches).  Then I gently place the inoculated biochar into that crevasse. That way I'm not tilling or grinding up the existing soil structure.  Most of what I have is trees and bushes, so I plant in a circle around the drip line of them. That's where the roots have the greatest growth and intake.   I have also planted the biochar into the raised beds and I'm excited to see it that will improve too. It makes a huge difference!  I have published my results here for a couple of years: https://permies.com/t/151346/year-biochar-results

John S
PDX OR

My current technique (always evolving) is to mix biochar and compost about 50/50 and spread it on top of a bed. Then I get out the broadfork. As I open up the soil, the compost-biochar blend falls into the cracks and the whole bed fluffs up. I then plant into this and mulch with copious amounts of wood chips or shavings. This is working pretty well on established beds.

When creating new beds, I usually put down some cardboard or paper, then layer lots of grass and weeds on top, and cover with a mix of soil, compost and biochar. Mulch goes on last.

Martijn Macaopino wrote:I work the biochar into the soil or work biochar containing compost into the soil.

Biochar works better when it's in the soil than when it's just on top of the soil and with the heavy clay soil here I'm really not at convinced that no-dig is a viable methodology. The soil is so poor here that tillage doesn't do any significant damage and I believe that as long as you are adding significant amounts of biochar and/or compost while turning the soil then it does improve rather than degrade.

Of course tillage isn't a long term strategy and I only plan to do that till a certain area has improved enough. Also im not talking plouging up the whole land here, just small areas selected for the cultivation of annual vegetables

Maybe we just look at incorporating it into the soil a little differently.  I drew a crude picture to represent what I mean.  On the left is the starting point, just showing a tree and the soil level.  On the right, a picture of how it looks after I first add a thin layer of coffee grounds.  After that a layer of compost (with pieces of biochar as chunks), and then a layer of wood chips.  So your soil level is 1.  When I am done, what is my soil level?  1, 2, or 3?  I would say it is at least 2, and within a relatively short time, the wood chips will break down, so now my soil level is represented by 3.  So I would say I incorporate it as well, just without any disruption or extra work on my part.  Your way is certainly a faster way of doing it.  I would say that my was is easier, and more "natural".  I don't think either way is wrong, just two ways of getting to the same place.

I did a test with charged biochar in our fall gardens and it made a big difference. I'm not sure how much was the char and how much was related to the release of minerals from it, but I think it's a combination of both.

This is what we're doing right now with the char:



It's a combination of many things together - getting the micros in there, plus encouraging fungally dominated soil.

And John - thank you for the link to your results!

Great video! It's interesting that you also found something that I found and I wasn't expecting.  The taste of several fruit improved dramatically after I put the biochar in.  Also some of the trees grew dramatically bigger after stagnating for years.

I also have evolved to adding several things to my biochar: whole wheat flour, calcium either in ag lime or crushed oyster shells, worm compost, leaf compost, rotten wood mycelium, and rotten fruit.   That's how I charge it.

I dig mine in, but we don't have sandy soil. I dig it in to the depth of the spade.  Here we have wet soggy clay. In the winter, our plants don't die from cold. They die from drowning and diseases caught during drowning.  Digging the biochar in at the drip line seems to improve the CEC, because if the soil drains better, the soil doesn't drown. Then it can breathe and exchange exudates in the soil, setting up the soil food web in the comfy hotels called biochar. It retains the moisture that it needs but lets the rest run free, and the minerals don't all wash out with the soil as much.  That's my theory.

John S
PDX OR

Yes, John! The transformation in flavor is very exciting. I really love to grow tree crops, but having just moved most of my experiments right now have been with annual vegetables. The radishes we ate from the biochar bed tasted amazing.

I am planting some Mysore raspberries this spring. In my old garden, they had a bland flavor. I am wondering if they will be transformed when they get into the biochar beds I'm making.

Paul of Back to Eden movie fame talks about this a lot.  I have heard many people talk about how the taste in food comes from minerals, and mineral depleted soils cause foods to taste bland.  It seems like these experiments are pointing towards that being true.  I personally use Sea-90 and Azomite, along with wood chips, to ensure all the minerals are accounted for.  I'm on a new property as well, so I'm excited to watch it evolve.

I can't believe I watched the whole video of John (the digger) and his wife just eating radishes, LOL. That's how much I miss tasty vegetables.
I will suggest my gardener friends to buy one small bag of biochar, just to test it. I've found a producer who sells it at 25€ for 10 litres, unfertilized, but we can mix it with our worm manure.

I have just added biochar to my second raised bed.  Vegetables, on average, tend to prefer a neutral ph, like 7.0.  We have naturally acidic soils here in PNWet.  Not only does the ash remnant make the soil more alkaline, I think that the greater diversity of microbes and drainage will allow the soil and plants to move themselves closer to their best condition.

John S
PDX OR