I appreciate that there is some controversy on the use of mineralized topsoil (MTS) as an aquarium substrate, but I would like to relate experiences on using this material as a nutrient enhancement for emersed plants in riparium planters. I have been using MTS in a casual way for a couple of months and my un-scientific observations suggest that it does improve plant nutrition and that it might serve as a long-term, slow-release nutrient source inside of the planter cup. In this first post I describe the general planting method that I use when including MTS in the planter.
The following picture shows the material that I used.
I acquired a box of this in trade with a member of another forum.
Proceeding through the steps of planting that I followed, the next photograph shows the planter cup with the basic substrates. On the bottom of the cup is a layer of Hydroton clay pebbles. These are topped with planter gravel filled to about 1/3 of the depth of the cup. Lastly, a shallow layer of mineralized topsoil was added on top of the planter gravel. I included 1 1/2 tablespoons of MTS.
If you look closely you can see that the MTS layer is below the level of the suction cup keyholes in the back of the planter cup. Since it will be covered with another layer of gravel this placement will help to prevent it from washing out through the keyholes.
Here is the plant that I used, a few stems of Ludwigia repens. It forms a pleasing floating carpet if planted in the Hanging Planter, then trained to grow across a Trellis Raft.
This last picture shows the planter with all substrate layers, Trellis Raft and plant. The thick top and bottom layers of planter gravel should prevent the mineralized topsoil from washing into the aquarium. It will be even more tightly held inside the planter cup as the plant roots begin to form.
With time to grow and some pruning to control shape, the plant will eventually cover the raft and planter from above and form a nice floating carpet of foliage.
The following picture shows the material that I used.

I acquired a box of this in trade with a member of another forum.
Proceeding through the steps of planting that I followed, the next photograph shows the planter cup with the basic substrates. On the bottom of the cup is a layer of Hydroton clay pebbles. These are topped with planter gravel filled to about 1/3 of the depth of the cup. Lastly, a shallow layer of mineralized topsoil was added on top of the planter gravel. I included 1 1/2 tablespoons of MTS.

If you look closely you can see that the MTS layer is below the level of the suction cup keyholes in the back of the planter cup. Since it will be covered with another layer of gravel this placement will help to prevent it from washing out through the keyholes.
Here is the plant that I used, a few stems of Ludwigia repens. It forms a pleasing floating carpet if planted in the Hanging Planter, then trained to grow across a Trellis Raft.

This last picture shows the planter with all substrate layers, Trellis Raft and plant. The thick top and bottom layers of planter gravel should prevent the mineralized topsoil from washing into the aquarium. It will be even more tightly held inside the planter cup as the plant roots begin to form.

With time to grow and some pruning to control shape, the plant will eventually cover the raft and planter from above and form a nice floating carpet of foliage.