A quick update and a question: I've located Calcined Sepiolite in Industrial Absorbent format, apparently the local fire department uses it on flammable liquid spills. Unfortunately, the particle size it's available in is tiny -- fine sand (The bonsai crowd appears to have ruled out all the Sepiolite kitty litters, as none of them are calcined and they all break down eventually. This leaves me with the following options -- I'm having a hard time picking which one to use as a Turface replacement in Al's gritty mix and would appreciate your opinions. I've not yet completely given up hope on finding a Turface equivalent but things are looking grim. On the bright side, I've been able to locate coarse silica sand for aquarium use, 2-4mm. It's a bit pricey but available within walking distance and I don't have to screen it. One ingredient down at least! Still trying to hunt down pine bark fines in the right size range, the cheapest chipper I've been able to find is a whopping 700! No rentals available. :( Closest fines so far are in the 10-45mm range, way too big. The search continues... Option 1: Calcined Attapulgite in industrial absorbent format, available in "4/30 grain size". Still trying to figure out what size that is exactly, though I know 15/30 is 0.5-1.5mm. Option 2: Mystery clay! A Calcined Kaolinite/Montmorillonite mixture (5-10mm) used in ceramic production as grog. (Learned a new meaning for an old word!) Grain size seems a bit big, no idea if the stuff breaks down or is phytotoxic -- I was unable to find anything on Kaolinite in agricultural uses except as a pest control agent. Montmorillonite percentage is uncertain. Seems they only sell it by the metric ton, trying to get my hands on a sample. Option 3: The same company produces LECA/Hydroton in small grain sizes, so-called "mini LECA". Available in 3 formats and 3 different densities: 350 ± 50 Kg/m3, 550 ± 50 Kg/m3 or 750 ± 50 Kg/m3. I'm guessing lighter = more porous = more water retention, so I'd opt for the lightest of the three densities. The formats are ground (0-6mm), sand (0-4mm) or fine (3-10mm). Pictures in the link below. Option 4: Our final contender is raw Attapulgite (non-calcined) in kitty litter form, mentioned in previous posts. Conflicting reports from the bonsai folks on whether the stuff breaks down or not over the long term. If you were faced with these options, which would you choose?

BER relates more to consistent moisture levels than it does to calcium. The problem does manifest itself as a calcium deficiency, but the ultimate cause is moisture inconsistency. The cal nitrate is mostly just a way to apply nitrogen. The calcium in it can help in some ways, but it won't cure your BER by itself. Experiment with your watering frequency, or maybe try setting your containers in a shallow saucer of water so they never dry out completely. If you are drilling drainage holes in a container like a bucket, make them about 2-3 inches from the bottom on the sides. That will give the plant a moisture reservoir so that it never completely dries out.

jamesvlad Nice looking plants, and very detailed information. I believe you said you were using Fermented rice husks 70% and 30% grit for the growing medium. I am wondering if there is a reason the rice husks need to be fermented, or if that is just the way they come (I have never bought or used them). Also I'm not familiar with grit. I did a quick search for that term and came up with basically large sand or small gravel particles, is that right? Do the rice husks become compacted? I assume if grit is large sand or small gravel, it's there to help with drainage and add weight for support. Just asking because I am always looking for alternatives to traditional hydroponic growing mediums. I really like using coco chips because it holds moisture well. But on a larger scale, considering I have a lot of 3 and 5 gallon buckets I want to fill, coco chips are not really economical for me because 50% of the cost is shipping. I need to have it shipped to me or take a 7 hour round trip drive, and unless I'm really stocking up that's a lot of gas money.

"I'm curious to know what mechanism allows the soil to maintain that level of precision irrespective of water pH and the application of fertilizers." Well..soil is a living breathing ecosystem with built in buffering capacity... There are two kind of acidity which are important for soil testing. There is the "active" acidity which is the acidity which the roots "see". The active acidity is measured with litmus paper, indicator solutions or a pH electrode. This is the acidit y people refer to when they want to know their soil pH value. The other kind of acidity is referred to as the reserve or stored acidity. Clay and organic matter in the soil tends to store acidity. It takes more lime to raise the pH value of a soil with clay or organic matter present than it would for a sandy soil with very little clay or organic matter. Therefore, soils with more clay or organic matter have a greater ability to resist pH changes. The buffer pH is measured with a weak base that starts out at pH 8.00. Soils that will require lime and have an "active" acidity pH value of 5.8 or below are set aside in the lab to have this solution added. The more the solution decreases from pH 8. 00, the more stored acidity the soil sample has. The computer program will then recommend lime according to the determined stored acidity of the soil. As an example, a sandy soil from the central part of South Carolina and a a soil from the Piedmont with plenty of clay each have a pH value of 5.5. This would be the "active" acidity mentioned earlier. The laboratory determination of the buffer pH va lue of the sandy soil, though, could be 7.80 while the buffer pH value of the soil with clay could easily be 7.30. Since the sandy soil has decreased the buffer solution pH value of 8.00 less than the clay soil (7.80 vs. 7.30), the sandy soil will get a lower lime recommendation since it has a smaller amount of stored acidity. In this particular case, to bring these two soils up to a pH value of 6.5 the sandy soil will get a lime recommendation of 0.50 tons per acre while the lime recommendation for the clay soil will be 1.00 tons of lime per acre...twice as much lime, even though they both have the same pH value. If you DID want to conside application of fertilizer, you would see that through a choice of mineral sources nutrient solution buffering capacity can be engineered, or at least guestimated to great efficacy. Both chemical and organic fertilizers may eventually make the soil more acid. Hydrogen is added in the form of ammonia-based fertilizers (NH4+) , urea-based fertilizers [CO(NH2)2], and as proteins (amino acids) in organic fertilizers. Transformations of these sources of N into nitrate (NO3-) releases H+ to create soil acidity. Therefore, fertilization with fertilizers containing ammonium or even adding large quantities of organic matter to a soil will ultimately increase the soil acidity and lower the pH. NH4+ + 2O2-->bacteria-->NO3-+ 2H+ + H2O hope it helped