I have a sourdough starter I created years ago, a sturdy rye/potato base inspired by a recipe in the cookbook put out by the Blood Root restaurant in Bridgeport.
Last week I had some turnip water lying around after making mashed turnips for dinner.
This may be a fantasy, but it appeared to me that the resulting loaf baked more evenly, and lasted days longer, than much of the sourdough I bake. I’ve used potato water as an extra ingredient many times, and typically put dried potato flakes in my non-sourdough sandwich breads. But turnip water, no, and I don’t think turnips have the same starchy properties of potatoes. I’m not getting any internet research action on the qualities of turnips in bread dough.
How did it taste? Sour and turnippy. Great for grilled cheese and Tofurky sandwiches. Great for buttered toast. Not so great for jams.
In any case, here’s the recipe. Note that I had yeast in this sourdough. That may seem like cheating, but it’s more about reliability in the rising. I add sourdough mainly for the taste. When I use my sourdough regularly, it can be the only rising agent I need, but gosh, I don’t need it to do everything. The yeast is right there in the refrigerator.

Sourdough with turnip water

Half-cup sourdough starter (mine is pretty heavy, fueled with rye or spelt flour and potato water)
2-and-a-quarter teaspoons yeast (my handy “yeast spoon,” purchased at the King Arthur Flour store)
3 cups turnip water (from the act of boiling turnips)
3 cups (approx.) white flour
1 cup (wheat flour

That’s it. No salt, no oil, no other added veg or fluids.

In a mixing bowl, ake a soft dough that’s not so soft that you can’t knead it with your hands. This can get sticky fast. You may need more flour than I suggested.You don’t have to knead as long as with white or non-sourdough—just so long as it’s blended and smooth and a little sticky.
Roll the dough into a ball, keep it in the bowl, and throw a dishcloth over the top. Let rise for 90 minutes.
After that 90 minutes, punch down the dough, knead it a little more, and put in a loaf pan. (I use a long ceramic loaf pan. Metal pans are not to be used with sourdough. Sometimes I use a rising bowl or no shaping vessel at all, but unless the dough is really firm it’s likely to sprawl a bit.)
Second rise should be 45 minutes to an hour.
Bake in a pre-heated 375-degree oven for an hour. You really want to make sure sourdough is fully cooked through.
Really interesting taste, with the turnip water. I’m going to turn what’s left of my last loaf into breadcrumbs/croutons now.