I have two short raised beds made of cinder blocks (8 in. and 16 in. tall) that isn't finished yet. I was wondering if it's okay to fill the voids of the blocks with excess soil from my yard? I live in a country where it never goes below freezing so I don't need to worry about moisture freezing and cracking the block. I've heard that soil inside a block can cause a moisture issue. But, it's being used as a retaining wall so it will have moist soil in contact with one face of the block always. What is the difference between this and having the moisture inside the block? Will filling them with soil causes the blocks to degrade faster? Is there even any structural benefit in filling with soil?