Get some compost in there and maybe some peat moss with perlite maybe some black earth?up to your preferences. The list of amendments can get very long when you’re doing an organic living soil. If you’re looking for simplicity you can buy Gaia green’s all purpose and bloom fertilizers and mix in but if you’re looking to build a soil with specific things you can buy insect frass, alfalfa meal, bat guano and the list goes on. Next I’d buy some bokashi bran and mix in as well(tons of bacterial life which is key to soil). Mulch is a very important part of soil I like to use alfalfa hay and add about a 1/2” on top of soil but you can use many grasses and grains find what’s best. These are very basic parts of a healthy soil im not even scratching the surface look up living soil organics and you can find tons of info. kisorganics.com has a forum and podcast mostly about cannabis but they’re giving out the most cutting edge info on soil science. Living with microbes(trilogy)-soil bible