that looks like a super soil. guess a premade one. i read that you can do that method to not burn your plants but also if your watering that you dont want to water til run off as you'd be leeching all the nutrients in the soil so if you do water to run off you'd have to add more ammendments down the road. idk though i never used it but i've seen people doing both waysnever tried it but i read about it once and people say it works
https://www.amazon.com/gp/product/B00S1HRLPQ/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B00S1HRLPQ&linkCode=as2&tag=growwcom07-20&linkId=NB6QZIT7DTNBBKZG