has anyone tried these soil amendments for thier citrus containers:

1-biochar
2- worm castings
3- composted leaves
4- bokashi compost

any experiences in these mixes or others?

None of the above. - Millet

You can basically use biochar in lieu of perlite; just like perlite, the size of the granules is important (most ~half the size of a pea, with some smaller and some larger); I also often use larger-sized pieces of bio char in the very bottom of the pot to prevent other materials from spilling out of the holes but allow water to drain through. I haven't specifically used any of the other materials you mentioned, but I do have a 15 gallon pot that I keep full of good organic material for potting use, and I use a little for citrus - perhaps a handful for a 3 gallon pot. It's an ever-evolving mix containing mostly leaf mold, (traditional) compost, composted palm fronds, and just a bit of native soil, and it certainly has worms in it. With the leaf compost, bokashi, or worm castings, be wary of using too much, since they all hold a fair amount of water and break down to create a heavier mix.

A comment: Citrus require mediums that give very good drainage, the use of the items you list above would be acceptable if used in smaller amounts, otherwise they are items that might cause the medium to retain too much water, thus not enough aeration. Elsedgwick's mention of bio-char as a replacement for perlite, calls forth another item I have been reading a lot about, is the use of rice hulls now being used by many commercial growers as a replacement for perlite. - Millet

I've been blending biochar into my potting blend this past year to improve drainage and reduce weight. I did an experiment in my garden at least 5 years ago and built a 4'x4' raised garden bed that was 50% biochar by volume. I could leave my garden hose running on it without making a puddle while the control bed I made at the same time without biochar had nowhere near the same ability to drain so rapidly. Both beds perform well. Initially biochar is hydrophobic, but it might have adsorbed water loving organic molecules onto its surfaces by now. I'll have to go out and repeat the hose test to see if the drainage has changed over the years. Also I'll have to pull a piece of biochar out, dry it and see how long it takes to absorb water compared with a freshly made piece.
Even if the biochar becomes a sponge for water, with the right particle size it should still allow for very good drainage. The stuff I make is pretty chunky and I don't grind it, I just crush the really big stuff.

BIOCHAR AS A SOIL
AMENDMENT

http://www.crec.ifas.ufl.edu/extension/trade_journals/2012/2012_Apr_biochar.pdf


i liked to share this article about biochar. although i don't know how effective is on container plants.

I think you have to differentiate Ag soil and cobtainers, anything applied to containers will have a greater effect than to soil where it has a vast area to disperse
worm castings contain live worm eggs, large worm populations not so useful in containers, maybe liquid worm juice better.
Leaf compost + Bokashi, could be hazardous to very young seedlings.
Solarising the above 3 may be beneficial ?
Biochar looks like it has good properties, but what about effect on pH ?

Also are you using them as ammendments/additions , or as a major part of your container mix ?

I measured the pH of my char and it checked in slightly alkaline...pH 8, but the char itself should be neutral. I think the slight elevation came from a bit of wood ash that formed due to my process...a little oxygen does get in and a tiny amount of ash does form for me. I figure that that bit of CaOH and MgOH that forms neutralizes out with the mix.

So far I'm been a bit of a wimp and have only blended it in at about 5 % by volume to see if anything bad happens...none observed. I'll have to step up the percentage to see how it behaves when it's actually at a percent that's large enough to balance drainage and water retention...I'm guessing 5% is much too low, but I haven't made time to do any measurements. That's what winter is good for here, extra time to tinker when my yard is buried in snow