FOSS gamedev and creative worlds

One thing that really bugs me when walking around in-game is the frequency with which deserts spawn. I've poked around in the game files, but I can't seem to find what I'm looking for. What I want to do is modify(reduce) the rate at which deserts are encountered.
The map_meta.txt file in ~/.minetest/worlds/ contains a line "mgv6_freq_desert = 0.15", but changing the value doesn't seem to affect anything.
Any help pointing me in the right direction would be greatly appreciated.

You shouldnt modify map_meta.txt of an existing world. That is not good.

The proper way is, set mgv6_freq_desert in minetest.conf and create a new world, it will contain the setting in map_meta.txt then.

Yeah, modifying an existing world felt a little kludgy to me. I'll make the change and test it out when I have more time. Thanks for the prompt reply.

Hate to cast Animate Dead on a thread, but does a lower number correspond to a higher spawn rate. I've been out of the loop for a while and just upgraded to the latest stable version(0.4.10).