Having a dirt tank isn't as easy as just adding dirt then covering it with sand.... Since it looks like you're fairly new to planted tanks here's my suggestions based on being in the aquatic hobby for 23 years.
So your tank dimensions are 30" long X 15" deep X 21" high, now my question is what type of planted tank are you looking to do? Depending on what you want in your planted tank will depict the type of equipment the tank will need... For instance lets say high light planted tank, what this means is you'll have intense lighting such as a T5HO lighting fixture, this will mean that you'll need a automated co2 system, and a fertilizer dosing regime.
So lets discuss my old 75 gallon high light planted tank for a minute...
Here's a break down of the tank...
Lighting - 48" Coralife Freshwater Deluxe 4x65w, 48" T5HO Dual Lamp Fixture
Filtration - Eheim 2213 canister filter, Jabao 915 4-stage canister filter
Heating - 300w Hydor Theo submersible heater
Substrate - 2" Mineralized Topsoil, capped with 1/5" Flourite planted substrate, capped with playsand
Co2 - Azoo co2 regulator with a 10lb co2 aluminum cylinder fed into a Rex Griggs DIY co2 reactor attached to a Magnum 350 canister filter outflow
Fertilizers - EI dosing regime using dry fertilizers combined with osmocote plus root tabs
The lighting for this tank was a little excessive, but it gave me great plant growth because of the bulb selection I went with. The Coralife light fixture had a combination with the left front bulb was 420nm actinic, right front was 6700k bulb, left rear bulb was 6700k, and right rear bulb was 420nm actinic. Then on the dual lamp T5HO it had 6500k bulb in front, and 3000k bulb in the rear.
Since I've moved on, my latest planted tanks I chose to go with a T5HO quad lighting 4x54w; The reason for going with T5HO was simple, the bulbs are easy to find, and cost less compared to the Coralife deluxe power compact bulbs. Not to mention that it made it easier to manage the wavelengths of the bulbs. Here's a image of live plants photosynthesis wavelength peaks, as well as the pigment protein complexes wavelength peaks. Now why are these important is simple, plants have 2 chlorophyll stages in them, chlorophyll A and chlorophyll B. Each stage has different peaks of absorption...
So with a T5HO quad lighting 4x54w system I had the following bulbs, very front bulb is a 6000k, 2nd front bulb is a power chrome aquaflora, 3 bulb is a wavepoint ultra growth wave, and the 4th bulb is a 12000k 460nm white actinic. This selection of bulbs gave me the perfect lighting selection for optimum growth for the plants, here's the ultra growth wave wavelengths...
As you can see from the ultra growth wave image, it covers all of the chlorophyll A & B peaks, as well as the pigment protein peaks. So in my personal opinion I'll take T5HO lighting over LED every time... Now back to the dirt tank...
I preferred to go with minerlized topsoil as the main substrate because what the mineralizing process does is help to enrich the dirt by bringing out all of the minerals for the plants to feed on, unlike a regular dirted substrate means that it still needs time to break down into usable minerals and during the break down period it releases carbon dioxide gases that can get trapped in the substrate and form gas pockets that can kill your fish, and plants. Whereas mineralized topsoil is already broken down and the minerals are immediately available for the plants to use.
Here's a link on how to mineralize topsoil
http://www.aquaticplantcentral.com/...-mineralized-soil-substrate-aaron-talbot.html
So I would take it slow, read as much as you can about planted tanks, and then decide what route is best for you!!!
Also, that's just sand on the leaf of the anubias plant, however you never want to bury anubias in the substrate because they have a rhizome and if you bury it the plants will start to die. This is why you see most people attach anubias to driftwood or rocks, the same goes for any java fern species of plants. Hornwort is a very easy plant to grow, just toss into the tank and let it float around, and it'll grow like crazy.
