A few growers place charcoal in the bottom of containers to absorb excess salts and maintain sweet soil, if plants are grown more than a few months.
It is hard to get enough charcoal to do this
( z1 hard :ARG1 ( z2 get :ARG1 ( z3 charcoal :ARG1-of ( z4 have-quant :ARG3 ( z5 enough ) :ARG6 ( z6 do :ARG1 ( z7 this ) ) ) ) ) )