Justin Glover

I've recently become curious about this as well.  I recently read a paper that investigated using different types of agricultural residues and pyrolysis temperatures to increase CEC in "weathered" brazilian soils.  As I recall, they had the largest increase in CEC using dried coffee husks pyrolyzed at 350C for 30 minutes.  I also recall another paper showing where palm fronds pyrolyzed at an estimated  320C in a cone pit showed significant improvements as well.  This was in an area where I assume palm kernels are grown for oil/fat production.

Here in SC, I would have to source different materials to use.  I've been thinking about just collecting yard waste from all the neighbors, but theres probably >98% chance that persistent herbicides will have been used in the source area.    I'm thinking about experimenting with using palmetto fronds as they're somewhat plentiful here.  Perhaps I can experiment if I can find some material from known un-poisoned land, vs. the stuff that I get from the neighbors.

The little information that I've read so far seems to indicate that certain non-woody "high ash" K? biomass sources are best for improving CEC in sandy, poor soils like what we have in the lowcountry, though it must be added gradually over the course of several years to minimize severe PH increases.

My next door neighbor has numerous citrus trees in her backyard.  I will say that it is well protected by it's smallish size, fencing, outbuildings, and the fact that a significant area is concrete (lots of mass/heat buffer).  

She has different varieties; some are in the ground & some are in large pots, but they all stay outside year round.  I'm not sure of which varieties they all are.  Usually when I ask, the common name she gives is something like Japanese orange / lemon / grapefruit.  She is originally from Japan.  

She does have a fairly large tangerine tree that her husband bought from one of the home store garden centers approx. 15 years ago and it produces proliferously most years, probably due in part to the fact that he kept a compost pile continuously fed near the base of the tree.  I think that they taste very good, but I also dont mind all the seeds.

usda zone 8b

I give this seed source 9.9 out of 10 acorns.  

As their name implies, Strictly Medicinal Seeds is primarily focused on selling medicinal plant seeds.  I've ordered from them a couple times and found their service & way of doing business was quite nice.  Along with seeds, they also sell botanicals and live plants, as well as some seed & medicinal processing equipment.  They also have a limited selection of cover crop seeds as well as fruits, grains, and veggie seeds.  

Their seeds come in small paper envelopes and their catalog is compact, printed in black and white so there is minimal waste involved, at least as I perceive it.  You can also download a PDF copy of their catalog from their website.  

The proprieter, Richo Cech, seems very knowledgeable about medicinal plants and although I haven't personally interacted with him, I have seen that he appears to be eager to help and quick to respond to people who have questions.