Soilbuilding in the developing world

[dice]

Originally Posted by dice

The composting process tends toward neutral
pH, whether the inputs are acidic or alkaline, so that is one
way to use something like seed meal or post-oil-extraction
seed cake without making significant changes to the soil pH.

Apparently rice paddy flooding tends toward neutral pH, too:

Effect of flooding for a rice crop on soil phosphorus and soil pH:
http://msucares.com/crops/college/07...-with-rice.pdf
(Acidic and alkaline inputs via the mulch can be ignored for any
effect on pH for the subsequent rice crop. No need to compost
neem seed cake or any other post-oil-extraction seed cake
before adding it to a mulch on a crop in rotation with rice. I am
assuming that adding inorganic P2O5 is not practical in your
application, so adding phosphorous would happen via the mulch
or manure.)

A document on rice in rotation with sugarcane in the Florida
Everglades ( http://edis.ifas.ufl.edu/ag123 ) mentioned that
the rice crop is usually fertilized with calcium silicate slag
(from some industrial process would be my guess) to raise
silicon levels that boost both rice and sugarcane production.
This would be a positive side-effect of spreading granite dust
(or other rock dust) on top of your mulch when growing
vegetables or other crops in rotation with rice. (It does not
need to be composted first, although adding it to compost
will help the compost itself by raising earthworm populations
in the compost.)