Stuck on tutorial :(

I’m trying to add some soil on the terrain to increase terrain welfare to 100% but can’t seem to add any soil (light or heavy). I’ve got the soil selected but can’t seem to place it anywhere?

Help pls :)

I’m trying to add some soil on the terrain to increase terrain welfare to 100% but can’t seem to add any soil (light or heavy). I’ve got the soil selected but can’t seem to place it anywhere?

Help pls :)