Bonsai do not require anything special. Just like all plants, they need some nutrients in large amounts ( macronutrients, e.g. N: nitrogen, p - Phosphorous, K - Potassium being the main 3). They need some others to a lesser extend (e.g., Fe - Iron, Ca - Calcium) and others in a very low amount (e., Manganese). All in all it needs to be balanced (Think your ow diet: You need a bit of everything, not just potatoes 3 times a day)
By using some different fertilisers throughout the year you will vary the exact composition of what you give, which will reduce the risk of missing one of them.
Growth of plants is limited by the nutrient that is lacking in their system over medium term. So you can add loads of NP and K. But if the plant is in need of Calcium that is not going to help the plant a lot.
I use chicken manure pellets, some kind of organic pellets, most likely bone & nails. And I use liquid fertiliser '1$/liter from a discounter'.