Acidic Inoculants?

I am new to the bio-char arena and am excited, but also don't want to ruin the tender soil in this area.  We have "strongly alkaline" soil. (There are many fields covered with white alkali.) The rocky, dry, sandy soil is extremely alkaline; daily winds between 20-65mph and only 6-10 inches of annual rain.

Since biochar is effectually alkaline, I was hoping to find ways to utilize the water-retention capabilities of biochar while mitigating the alkalinity as it breaks down.  

It looks like certain feedstock (bamboo and pine needles) may have an acidifying effect when it's biochar is added to alkaline soil. I have yet to look into pyrolysis for pine needles.  However, would there be certain inoculants more acidic in nature that would compensate or mitigate the alkaline biochar? Basically making the biochar more neutral or even acidic?  Any suggestions?


References:
http://biochar.pbworks.com/w/page/9748050/Soil%20pH
https://soilseries.sc.egov.usda.gov/OSD_Docs/S/SAN_LUIS.html
https://www.usclimatedata.com/climate/alamosa/colorado/united-states/usco0004

This is a great question. I advocate inoculating with nutritious items that are inexpensive to you. I have an orchard, so I use rotten fruit, which should be acidic.

I heard, not sure where, that bokashi liquid (the liquid that drains out of a bokashi bucket during fermentation) is a good and acidic inoculant for biochar. Makes sense that it's acidic, it should be something akin to the juice from lactofermented veggies...

It is a whole process, but there is potential for wood vinegar to be utilized.

Honestly, I wonder if 'regular' vinegar could be used to the same effect. I'm trying to think of 'free' sources of acidification for biochar and coming up without a whole lot of ideas.

Keep in mind that the ph of biochar can vary. I have seen reports from neutral to very alkaline, like 11.  I think it mostly depends on how much ash is in it.  I try to be careful not to leave too much ash. Mostly I do that by trying to stop my TLUD by drenching it with water at the right time, before too much ash is generated.  NOrmally, I have a very small bit of wood that is not completely burned and I have to save it and burn it the next time, which is not a problem.  

I have read before that urine is neutral as it leaves the body, so I would definitely also use that. It's free and convenient.  

As Eino referred to, almost anything fermented will become quite acidic.  If you have old vegetables that you cut out, or banana peels, orange rinds, coffee grounds, compostable stuff etc., fermenting them would make them quite acidic.  That seems like the easiest and cheapest thing to do. Put them under water with a rock on the lid, or whatever your favorite method is.

John S
PDX OR

Such helpful input, Eino, Timothy, and John, thank you!

Eino, I actually started using the bokashi method this year and love it.  What  I haven't figured out yet is if I need to aerate the bokashi tea or not. (Since bokashi uses anaerobic environment.)  Definitely will try the lactofermented juice, that is a great idea.

Timothy, that is an interesting thought about wood or any vinegar, I'll look into that.  

I'm trying to think of 'free' sources of acidification for biochar and coming up without a whole lot of ideas.

I would love to hear any of your ideas!

John, Thank you for pointing me the right direction.  I have read many of your posts and tried to glean as much as I can from your experience, thank you for sharing what you have learned!  I have a stash of biochar saved up and planning on rinsing off any residual ash, I assume before soaking it in water. Also keeping the biochar as larger pieces and not ground down too much.  Regarding the urine, I wonder if rabbit urine would work well, as I try to separate rabbit "pellets" from the urine.  For the compost, I definitely use a lot of citrus, banana peels, veggies, etc. in my bokashi composter.

Appreciate any all all ideas!

Yes, I think rabbit urine would work well, but you may have a source even more reliable and convenient than that.

The compost sounds great, although I will warn you.  Red wriggler worms and earthworms are said to hate citrus.  So you may compost the citrus in a separate way.  We throw our alliums (onions, etc) and citrus off the deck so it just lands on the surface of the garden.  Worms avoid them, so I don't want that in the worm bin or the compost pile.  Once they decompose, I'm sure worms won't hate them as much.

Bigger chunks of biochar are better for very arid conditions. They conserve water in them.

John S
PDX OR

Thank you John!  Yeah, the citrus (and everything you can't put in a hot compost) gets fermented by the bokashi composter, so the worms don't get it until it after it is processed, then they love it.

Excited to employ all the ideas and see good results.

Working on a 200 sq ft garden over alkaline (ph 7.8) silt-sand, I just covered a 2" layer of 50/50 silt-sand biochar mix with a 4" layer of composted horse manure. The resulting planting mix is probably high in salt and ph so I'm interested in reviving this thread.
My plan is to hose the bed down (we only get 11" rain per year), then let the compost filter into the biochar for 6 months of inoculation. About a month before planting, I intend to add soil sulfur to bring the ph down then use a broad fork to blend the top 12". My goal is neutral ph.
Anyone see a problem with this approach or have suggestions to optimize results? Thanks for sharing any experience!

Seems to make sense.  Lack of rain is one of the main reasons for alkali soils, as the calcium, etc. is never washed out.

John S
PDX OR

Amy Gardener wrote:Working on a 200 sq ft garden over alkaline (ph 7. silt-sand, I just covered a 2" layer of 50/50 silt-sand biochar mix with a 4" layer of composted horse manure. The resulting planting mix is probably high in salt and ph so I'm interested in reviving this thread.
My plan is to hose the bed down (we only get 11" rain per year), then let the compost filter into the biochar for 6 months of inoculation. About a month before planting, I intend to add soil sulfur to bring the ph down then use a broad fork to blend the top 12". My goal is neutral ph.
Anyone see a problem with this approach or have suggestions to optimize results? Thanks for sharing any experience!

To me this sounds on the right track. Have you looked into gypsum(calcium sulfate dihydrate)? A mineral that has not only sulfur but calcium too. Either will take time but I think that even if you don't get a soil test to 7, if there is enough micro organism diversity and roots in the soil they can manage the rest. It will get better over time. Gypsum should help with soil structure some as well as long as you don't already have an overabundance of calcium for some reason.

Humates are thought to lower pH in a high pH soil and raise pH in a low pH soil. How humates work is somewhat of a mystery, started using them in 2025, both liquid and granular.

blackearth.com

Thank you all for your replies John, Les and Doug. In my case (as John alluded), the land and ground water have an excess of calcium as well as magnesium (limescale everywhere). Sulphur without calcium is necessary in my case but other readers without the excess may like the gypsum option.
Doug, the background that you provided is helpful in expanding my knowledge of options (apparently Northwestern New Mexico is a humate mining region). I will look at the viability of local sustainable options. Thanks for expanding the possibilities.

Amy,

You may want to check for an OMRI label on any humate you are considering, I am organic here so that is why I use Blackearth humic/fulvic acid. What is nice about humates is you need so very little, with the liquid it can be as little 8 to 16 ounces per acre in furrow. At $17.00 per gallon that is quite a reasonable fertility amendment. Humates are thought to make available the trace elements that can be complexed in high pH soil like I have here, my pH is in the low 8's. I do not get too caught up in soil pH as a high number likely means high potential fertility. I have high calcium, magnesium and potassium, all good in growing plants, need a working soil to make them available. Soil pH can fluctuate by quite a bit during the growing season as plants have the ability to somewhat adjust pH to their liking.

Got our soil test results back from Cornell Soil Lab, wow, so much great, new information. The 6 samples I sent in range from 7.2 to 7.7 pH. Yea !! My previous standard soil tests always came back in the low 8's. We did put on about 550 pounds per acre of gypsum in 2025 and this may have been partly responsible for the pH reduction although gypsum is thought to be pH neutral. This gypsum came from a mine in Ft. Dodge, IA and is known to be very pure. What I did notice in our garden this summer when using this gypsum if I got it on the leaves it could burn. I wonder if the sulfate in this gypsum is a bit faster reacting than is the calcium, hence the better pH readings? As it turns out we have adequate sulfur in our soils, some a bit excessive, maybe due in part to the added gypsum in 2025. Have used a lot of gypsum in the garden over the years, all in pelletized form, so the gypsum fines from Ft. Dodge are I think, a valuable nutrient source.

The good news is our soils are working biologically with 100% available phosphorus on all tests. No shortages in micronutrients (trace elements) so we will do no soil correctives this season. Will fertilize for the crop being planted with the idea the higher organic matter soils will have more ENR, estimated nitrogen release. We have a good way to go on building our soil organic matter (ranging from 1 to 5%), but the basics seem to be met, fertility wise. A living soil should soon follow.

We have the good fortune here of having some native prairie remnants to use as our reference soil. These soils are in equilibrium and give us a good guideline for nutrient balancing and potential soil organic matter improvement.

Congratulations on your efforts to bring down the ph in your fields Doug. Your dedication to testing, recording the inputs, testing again, then recording the soil changes are really admirable.
Now I am wondering about the scale of our respective projects and how that influences choices to achieve our goals.
Reading your posts, it sounds like you are running a real farm and working to amend previously farmed soil that may have been depleted or changed. Soil recovery sounds like the dream of the professional organic farmer and you are achieving that vision. Your clear guidance will help all readers optimize their outcomes with a land recovery goal. Your solutions are elegantly direct.
In my case, I am working a 1 acre property with a desert garden that is 200 sq ft. After clearing the dead saltbush in this area then burning them, along with some fruit tree trimmings, to char, I realize that I need some kind of living inoculant that can populate the micro-pores of that charcoal to achieve a living soil. The inoculants for biochar may come from decomposed horse manure but I thought, maybe, adding something extra (I'm thinking about a very small and local scale) could help build a tiny island of living soil that now includes little bits of charcoal. So the question arises, what can I add that is readily available in my local environment that could add life to my wanna-be biochar and, ultimately, the soil? It is a meandering journey! I'm using up the debris on the property and trying to reincorporate it into the land as biochar. This approach is really an extra step to contemporary land recovery: why even bother with biochar?  Well that's the funny thing: I'm super curious what I can do with the stuff that is already here in the yard.
In my case, I have a bag of soil sulfur sitting in my garage that came from the local feed store a mile away. This probably is not really a locally produced product but it is one that I happen to have and I'm wondering if I could amend my soil with that and do no harm. Alternatively, I could try some other household (homemade) acidifying compost additives that others have mentioned but have no real data or long-term experience to show results like those that you have achieved with the Blackearth humic/fulvic acid and/or gypsum.
What I've learned here is that we probably need lots of options to repurpose the products that accumulate over time in a semi-suburban consumer culture. The farmer may have the best options with the most data supporting the professional choices. But there is a delightful challenge in the smallest scale experiments to improve a little garden using what shows up.

Biochar retains 6 times its volume of water, so I would think it would be highly useful in a desert situation.  I would start with things that naturally grow there, improve the healthy soil "island" and spread out from there. The more you have growing, the larger number of things you can use to help bring your soil closer to 7.  Definitely fermentation comes to mind.

John S
PDX OR

Amy,

I like your all things considered approach to soil improvement. My organic farming journey is in its infancy, but my organic gardening (7 years) has been my proving ground for what we are doing on a larger scale. Adding and managing organic matter would be my first priority. As your soil organic matter (SOM) improves, I think your soils will start working biologically and your pH will head closer to the neutral point (7). This is what I believe we are seeing here. Our management practices of minimum and shallow tillage along with soil friendly amendments are showing up as lower pH and high phosphorus availability. I have never considered high soil pH as a detriment, it is a sign in our case of a high inherent soil quality. Our soils are high in calcium, magnesium and potassium, thus the high pH. Modern farming practices have done nothing to improve SOM and soil biological activity. Far better to have high pH to work with than an acidic soil. A small scale is much easier to work with than a larger scale as you can actually amend a garden size area to get things in balance. Not so on a farm scale, soil short of the macronutrients cannot be improved affordably. The renowned agronomist, Donald L. Schriefer, says you can't even bring up some of the trace elements like iron and manganese affordably. Better to add them in row to provide balance in the root zone. Microbial activity is the key to soil health and improvement, feed the microbes (cover crops and the like) and good things will follow. Soil hardness is also a very important factor in soil biological activity, soil needs oxygen, compacted soil does not allow it. Residue management is the number 1 priority (managing soil air)) for Donald Schriefer, you must have a conduit from the soil to the atmosphere to allow the exchange.

Thank you for your suggestions, John and Doug. I am integrating the ideas offered and appreciate your thoughtful replies.
Consistent with Doug's experience, I did harvest abundant corn, beans, and squash from last year's 200 sq ft garden next to this new 200 sq ft plot, despite the high ph. The soil with added horse manure compost (soil organic matter) has produced well. This new plot will have biochar and compost so I am interested in comparing the results.
The older garden did require an exceptional amount of water so I hope that John's experience with the water holding capacity of biochar comes true for this desert garden.
I'm learning more each season!

Amy,

I think you need to consider your subsoil as part of your water management/soil productivity. I remember reading about the growing of ancestral corn in dry areas, they would plant it in a trench, closer to the subsoil moisture. If I remember right, they would fill in the trench somewhat putting the roots deep into the soil. Your subsoil can be a help or a hindrance in retaining moisture and fertility elements. Our farm is sub irrigated here because we are on the higher base of Glacial Lake Agassiz, the Red River of the North is to our west. We also have Stony Creek flowing through our farm so this is our local drainage low point. In talking with our soil contact at Cornell Soil Lab, she looked at the USGS Soil Map for our area to further understand our underlying soil. She said we have about a 5 foot layer of semipermeable subsoil that will hold moisture but will also drain to points lower. We have been much above normal for rainfall here the last 2 growing seasons so plans for planting of crops followed by cover crops have not happened. We planted the crops, the grain quality was high but yields were off due to too much moisture. I need to develop a hydrologic interface to what we are doing here, planting crops that will do best with the moisture conditions in the topsoil and subsoil in that given year. Our 3 main tillable fields all handle subsurface water somewhat differently.

Gary Zimmer says pH levels can move one to two points during the growing season, the plant roots adjusting the soil to their needs. Magical when you think about it but so are all things growing.

Doug McEvers wrote, "I have never considered high soil pH as a detriment, it is a sign in our case of a high inherent soil quality."

Most of our fruits especially, prefer a slightly acidic soil.  Lower than 7 is good. So is above 6.

John S
PDX OR

From the book, Eco-Farm   My guide to understanding soils for the last 35 years. This is somewhat condensed for brevity, but the point is made for balanced fertility.

"Calcium, magnesium, potassium and sodium, all four are strongly alkaline in character. The acid condition of the soil means very little if not related to the availability or absence of these major cation nutrients. In fact we will not deal with pH as such. By bringing calcium, magnesium, sodium and potassium into equilibrium, we will automatically adjust soil pH in a soil system suitable for plant growth. In the meantime, pH provides a clue, albeit one that can be easily misread if fundamentals of soil balance are not kept in mind".

I think that many sources of ideas is optimal.  

When I had my soil tested, it was very acidic. I live in the PNWet, an area of frequent drizzle between November and May.  It was very low in calcium, fine in Magnesium, fine in Potassium, and slightly low in Sodium.  I have steadily added ag lime, a great source of calcium, since then.  I haven't tested it recently, but I imagine that the soil is much more balanced than it was.

Have you seen those charts where they show during which ph range minerals are available? I found those charts quite helpful.

John S
PDX OR

John,

Start a thread," understanding your soil" or something like it. You have a good soil knowledge, I am home schooled on soil but learning quickly on the job. I was fortunate many years ago to discover Acres USA. Went to a couple of their annual conferences and found out there is a mainstream agriculture counterculture. Most all of what Charles Walters and Acres USA published and taught came from the great minds like Professor William Albrecht. His early soil testing and reports were taken from Malabar Farm in Ohio, a pioneer in soil rebuilding. I suppose his research would have been somewhat different if not for Malabar farm and its living soil, brought back to life with grasses, livestock and diversity of crops. The soils were badly damaged when Louis Bromfield started Malabar but were brought back to a highly productive state with good farming practices. Professor Albrecht was able to establish good nutrient percentage guidelines using Malabar farm soils for reference.

We can restore our soil, understanding where you are currently is where it starts. Life in the soil is ultra complex and we will never know all there is to know. But we know what works generally. covers, limited disturbance, a move toward soil balance. This gets life in the soil going and the unpaid workers go to work.