The chemistry of baking soda and how to use it for hair

You can experiment on it.  Baking soda reacts with oil similar to the process of soap making.  Therefore thick layers of grease in the kitchen can be cleaned up in no time.  You just rinse it off.

On the other hand, baking soda dissolved in water does nothing to oil.  This is a common fact that most things that dissolve in water or oil, do not dissolve in both at the same time.

Baking soda is completely opposite to soap and detergents that works on surface, and have a hard time to work on bulk grease.

So BK is ideal especially for oily hair.  If you apply BK to your scalp even after a week of nature camping with no shampoo, any oil and grease and odour disappear immediately.  Because the whole mass of hair has so many surface area, it's impossible to strip too much oil from the hair shaft, which can eliminate the need for conditioner.

Dry BK is messy and mildly abrasive.  So I use wash/rinse bottles with enough BK and water in it.  I keep shaking while applying to guarantee enough solid BK delivered to the scalp.

BK is pretty safe.  On a pH scale of 1 to 14, BK is at 8, one from neutral 7.  BK is used a lot medically and often to neutralize acids and maintain a near neutral pH.

BK is of course you can say "natural" and therefore biodegradable.  It doesn't degrade much as some form of sodium salt will always be there, which is natural occurring.  BK with hydrogen and carbon dioxide atoms could be safer than common salt with chloride atoms.

There should not be long term effects if you always rinse thoroughly.  And avoid excess stripping off body oil.  It may be a good idea to neutralize BK with organic acid.  Harmless sodium salts will be left and excess organic acid will degrade into something simple.

As for any shampoo and body wash, you may need conditioner and moisturizer for your scalp and skin.