My cats are indoor cats. I use a plant-based recyclable kitty litter. My garden is mostly clay because the builder scraped off the surface layer and probably sold it (I am currently building extra new beds with introduced soil). I apply the used kitty litter as fertiliser for my daylilies. It is the only fertiliser I use on them. I also keep an eye on acidity and apply lime when necessary. When I plant, I apply a handful of matured cow manure in the bottom of the hole. I don't use the litter in the vegetable beds. Epsom salts is something I had not thought of and will now use. I have to be careful with phosphorus because it is very poisonous to native plants, especially here in the low-nutrient wallum.
I have no sewerage. The present beds sit on top of the septic system so the area never dries out. However, the water is tertiary treated and contains no nutrients.
Regularity of fertilising depends on the cats and their efforts.
