Soil care...

Hi guys and girls. Quick question about soil care for potted cacti. I have a lot of small potted cacti and re-potting them every year is just to much effort and $$. What do you do to ensure that soil is in the best of condition to ensure good growth year in year out? (Apart from obviously adding fertilizer)

I've been adding coarse sand and sometimes rough orchid mix to my soils to keep them with a good consistency and improve drainage. Sand also works to distribute water around so helps with wetting and drying due to its hydrophilicity (water is attracted to the polar Si-O bonds). However it can be a lot of work to get the sand free of fine dust particles. If the sand has a lot of dust in it then it can do more bad than good.

Yeah I have found some sands to be good whilst others seem to bind together. I have tried adding marble dust to a few pots lately. In small quantities it is very good but overdose the soil and it turns into an impenetrable crust. Has anyone experienced a loss of lime from pots over time? I glanced over a post a while ago which stated that they add lime every year to help with coming out of dormancy. Is this a viable option and if so whats the best way to administer it without re-potting?

I use Pumice as base  for my soil mix. It breakes not up (like Spongelite), holds water and nutrients and makes it is easy to readjust the ph. There is no humus in my substrate which gives good growth in the beginning but degrades quickly and blocks the aeration later, making repotting necessary. I also avoid fines <1mm in my soil. If there is later to much salt from watering built up, I flush the whole thing from top with lots of water, readjust the ph and apply fertilizer as normal.
Thats not my idea, its from an old lady having some cacti (mostly Mammis) for 10+ years in the same pot.
Recently there was a link to a very interesting article of a Romanian Journal here in the forum  (about the "Stone Eaters"). Worth to read.