Hi and welcome to the forum
Tanks with dirt substrate are often problematic and regularly have prolonged issues with ammonia being released by rotting organic matter in the dirt. These tanks can't be gravel cleaned and eventually they fail because of the massive build up of gunk (mainly fish waste) on the bottom, which harbours harmful disease organisms. This gunk also makes it harder to treat the tank if the fish get sick. After a period of time, the ammonia being released by the substrate stops and you end up with mud on the bottom of the tank.
Having a dirt substrate is in my opinion a waste of time. If you want a heavily planted tank, use a fine gravel, add aquarium plant fertiliser, provide lots of light and after things have settled down in a month or two, add a few small fish.