Soap as Plant Food

10 years ago

Howdy YouÃ¯Â¿Â½ll,

We often have bits and chunks of whatÃ¯Â¿Â½s left (mostly used up) of bars of soap in our soap dishes (sinks, shower, tub etc.) over the years, I've seen rich plant (mostly grass) growth in areas where grey water runs out on to the ground (e.g. mountain cabin). I know that plants like potassium (sometimes in soap) but as for all the other stuff in soap, I donÃ¯Â¿Â½t know.

For example, we often use Irish Spring Aloe and here is a list of all the monkey business in it:

Soap (sodium tallowate, sodium cocoate and/or sodium palm kernelate), Hydrogenated Tallow Acid, Petrolatum, Glycerin, Coconut Acid, Sodium Chloride, Fragrance, Polyquaternium-6, Aloe Barbadensis Leaf Extract, Pentasodium Pentenate, Pentaerythirtyl Tetra-di-t-butiyl Hydroxyhydrodrocinnimate, Titanium Dioxide, Chromium Oxide Greens.

IÃ¯Â¿Â½m also wondering about Dish Soap (in bottle) etc.

There are some salts and acids in this stuff but I think only in miniscule proportions so they probably wonÃ¯Â¿Â½t matter.

Does anyone have any ideas e.g. formulas, methods etc. to make fertilizer with leftover soap?

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Comments (3)

wertach zone 7-B SC
10 years ago
"I've seen rich plant (mostly grass) growth in areas where grey water runs out on to the ground"

I don't think it is because of the soap, I may be wrong. I think it is the extra water.

IMHO, a better use is to put the mostly used up soap, before it breaks, in the shower with a new bar. Then when you finish your shower, using the new bar, lay the now soft from the heat and humidity of the shower used bar on top of the other, flattest side down. They will fuse together before you next shower, at least Ivory does. Then there is no waste!

I haven't thrown away a partial bar of soap in 40 years!
Kimmsr
10 years ago
What many people today call soap is really a detergent, indicated by the presence of "Petrolatum" or something similar, a by product of petroleum refining. These products can kill plants, they are not plant food.
Real soaps, made from animal or vegetable fats reacted with lye, are fairly good insecticides, but also are not plant foods.
In the grey water some places are allowing to be used to water gardens that is usually not enough soap or detergent to cause plant distress or provide any nutrition, although the soap or detergent can build up in soil to harmful levels if not diluted with clean water.
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toxcrusadr
10 years ago
I agree that the extra growth is probably mostly from extra water. Perhaps there is some contribution from K as you said, and also N content of some of the chemicals. Don't forget that the 'dirt' that gets washed away by the soap also has proteins, etc. so there is some N there.

I would not use it for plant food though. Surfactants dissolve fats and oils, and in high enough concentrations they will begin to damage the cell walls of soil microbes as well as plant roots.

I agree with wertach, reuse it as soap. When the glued-on bits are just too small or won't stick well enough to the new bar, I put them in a box. When the box is full, grate with a box grater, soak in water, and cast new bars in a bread pan lined with foil.

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Soap as Plant Food

Comments (3)

wertach zone 7-B SC

Kimmsr

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toxcrusadr

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