Our latest farm on Besevrona is the gravel and saltpetre farm. And as always, level 5 drops the same amount as level 6 planets. Source
The farm has a 2x3 plot area which contains 1144 gravel blocks (99%). The other blocks are 6 sand blocks and 2 clay, no stones or other annoying things.
The gravel farm can be reached through the Iconic Resource Hub.