More souls?
Zhang Xiaoman found the crux of the matter. A planet with only plants won't do; low-level plants simply cannot give rise to civilization.
According to normal evolutionary rules, the most common method to acquire souls is to wait for the planet to evolve on its own. As long as there's water and a suitable environment for life to thrive, after countless eons, animals will be born, which will gradually create their own civilization.
But this process is extremely prolonged, and waiting for them to evolve into a civilization could take an unknown amount of time.
Currently, the Boundary Value of the Original Realm does not support him using the authority to accelerate the flow of time, so acquiring souls through such natural evolution is clearly unrealistic.
