In the coastal habitat of Astrochelys radiata, the soil consists mainly of water-permeable, calcareous sand and rock of maritime origin. In the dry forests, a thin layer of humus is formed by falling and slowly decaying leaves, which is mixed with sand and weathered debris. Near river courses there are open and dense grasslands with a humus layer that can absorb and store moisture during the rainy season.
Inspired by this terrain, we use the following substrate types in both indoor and outdoor plants: In the dry zone, under heat lamps and at sunny spots, calcium-containing shell grit/algrite sand in grain sizes 1-6 mm has proven to be most effective. This shell sand does not dust even in very dry conditions and serves as a calcium supplement. It can be easily washed and, if necessary, sterilized in the oven at 100°C. In the transition zone we mix shell grit/algrite sand in the ratio 1:1 with garden soil. We also use this mixture in deep layers on the laying mounds. It provides good stability when digging and can be moistened sustainably. By regularly digging over the laying mound, moist substrate from deeper layers reaches the surface and the consistency remains nice and loose, which makes females that are ready to lay more likely to dig. Outside the dry and transition zone, we use pure garden soil. However, this should be moistened regularly (humidifier, ultrasonic nebulizer, spraying), otherwise it dries out easily and quickly becomes pulverized and dusty from the constant walking and weight of the turtles. For juveniles, tufts of grass or other suitable hardy plants can also be introduced in areas with garden soil.
The hiding and sleeping places are plastered with straw and foliage, so that the animals can easily dig in. Radiated Tortoises like it when loose, tactile resistance can be felt around the shell during the night's rest. It gives them a feeling of security and safety. In the wild or in an outdoor enclosure, large tufts of grass, low bushes and undergrowth are therefore preferred as sleeping places.
Excrements must be removed from the substrates daily, generously with a shovel. Due to residual contamination, all substrates must be completely replaced and recycled after a certain time. Always pay attention to cleanliness and hygiene in the indoor area! Since we keep a larger group of adult animals and an overuse of substrates is pre-programmed, we do without substrate completely in a large part of the indoor facility and keep the animals directly on a non-slip tiled floor, which we spray off 2x a week with a hose and can easily clean with a brush. However, this partial, substrate-free keeping in the indoor area is only legitimate because the animals can switch to areas with substrate at any time (laying mound, sleeping area) and there is direct access to the natural outdoor enclosure, which the animals can use independently every day in good weather from March to October.
Base your substrate selection on the natural habitat of Astrochelys radiata. Substrates with the following characteristics should be avoided at all costs: