I planted a Tuscan Blue Rosemary yesterday in relatively dry soil and watered it with the soapy saponin rich water from soaking broad beans for planting.
There are good reasons for not pouring this “waste” water down the drain. First, in bone dry places like New Mexico, using water twice is good practice. Second, this water is packing water soluble nutrients for your plants that leached out of the legumes when soaked. I consider this a free to me liquid plant fertilizer.
Another benefit is for house plants particularly, because they easily dry out to the point where the water passes through without moistening the soil. The very thing you are soaking out of your beans, saponin, is a natural surfactant (wetting agent) that holds the water in the soil. The saponin molecule attaches to water at one end and to soil particles at the other end, preventing the water from passing through. Add in the bioavalable nutrients from beans and it is also a good plant starter for outdoors.
I added this pint of water to a gallon of rainwater collected from my back porch roof:
As you can see, my rainwater has a bit of soil in the bottom as well. No problem, soil adds minerals to houseplants when I water them with collected rainwater, and I never repot due to depleted potting soil, because I increase micronutrients on an ongoing basis. I just stir the water enough to cloud it with the tiny bit of soil and its attendant microrganisms.
One note regarding sterilized soil medium touted by the market economy. Killing live soil is bad for the soil and bad for plants. Live microrganisms in soil “feed” minerals to plants and plants “feed” sugar water to soil microrganisms in return. This is a critical cycle that keeps minerals coming to stationary plants. Plants release hydrogen ions into the soil moisture that lifts metal ions stuck on the outside of soil organisms. Releasing them of the weight, I suppose. Organisms cluster around plant roots, receiving sugar water and releasing minerals. Both pesticides and fertilizer kill the microrganisms that feed plants naturally. Luckily, sterile cannot survive long, because trillions of microorgisms float into the pots on dust. One of the functions of trees is that they capture dust from the wind and when it rains, the fresh nutrients and soil biota are added to the soil beneath it. Over time it is a bit of an equalizer between nutrient dense soils and depleted soils; and between locally damaged soils and live soils.
The main argument used by the market economy for sterilization is soil-borne pathogens are killed. A healthy plant deals with pathogens every minute of the day (as do we). Saponin itself is made by plants to kill plant pathogens, and does so without killing the soil biota critical to plant health. Sterilization is like using a nuclear weapon to deal with a burglar.
It is common knowledge that people cannot digest saponins in legumes, and this is one reason why we soak them before cooking.
Some saponins are cut by intestinal bacteria, removing the sugar and releasing the other half to attach to the intestical wall, creating the holes called leaky gut syndrome. This same process allows some saponins to adhere to cancer cells and limit their growth. They can cause apoptosis of cancer cells by inducing mitotic arrest, which puts cancer cells into the natural cell death and cleanup system.
New research shows that there are at least 11 classes of saponins and that more than 150 individual types are found to possess significant medicinal benefits. Little is known at this time about the different saponins, and so far research only holds for one type at a time. Some of the results show that plants produce saponins to fight infections by parasites and when we eat them, they help our immune system protect us against virus, bacteria, and other parasites. A steroidal saponin can protect from bone loss. Some saponins naturally increase testosterone leading to muscle growth, increased strength, and enhanced athletic performance (this one is already sold in the market economy).
Amazing stuff. My little use of saponins in my garden seems like small beans in comparison! However, using just a little over a gallon of nutrient dense water with saponins to bind it to the soil around my small plant, I have “watered in” The Tuscan Blue Rosemary with extra nutrition to encourage root development into surrounding soil. Good enough for me.