Turnips didn't bubble at all

My first pickling experience I tried to make turnips and followed recipe from home preserving bible. 1 pound shredded turnips 1/3 cup pickling salt with three inches of headroom mashed the turnips under the juice put brine filled bag on top and left jar uncovered for three weeks at 67-74 degrees. There was no bubbling at all. The turnips turned brownish. They tasted crispy and pickled but absurdly salty even when rinsed. What happened?

I am not familiar with the brine filled bag on top. Can you elaborate on that?

Ferments need to be able to release gas and some bacteria (kombucha scobee) is sensitive to coming into contact with metal.

I wonder if the bag had a residue which impeded the ferment.

I use glass pickle stones to keep the mash under the brine.

In my experience when the fermented vegetable turns brown it is due to oxygen exposure or high temperature. It sounds like temperature was not the issue.
Did the recipe tell you to leave the jar uncovered? I've never heard anyone recommend doing that. With a lid on the jar the CO2 will build up and will cause the ferment to bubble. With a lid on you must burp it regularly to allow these gases to escape, because the pressure will build. If you ferment without a lid then I would imagine that would prevent any noticable bubbling and would expose the vegetables to oxygen, even when submerged under a brine.

Also, 1/3 cup (6tbsp) of salt is way too much for 1 pound of turnips. This recipe reccomends only .5 tbsp per pound of turnips: https://insaneinthebrine.com/sauerruben-fermented-turnips/

I was going to question the amount of salt as well. Too much salt will inhibit bacterial growth, so that might have been your problem.

For fermenting vegetables, my standard ratio of salt to vegetables is 1 tablespoon salt to 1.6 pounds of vegetables. If I need to add more brine, it's the same ratio 1 tablespoon of salt to 3 cups of water.

Joseph Lofthouse wrote:For fermenting vegetables, my standard ratio of salt to vegetables is 1 tablespoon salt to 1.6 pounds of vegetables. If I need to add more brine, it's the same ratio 1 tablespoon of salt to 3 cups of water.

Same here.  I use far less salt than that Daniel.