I’ve never taken soil samples of my garden or on any farm where I’ve worked. I have read about and taken classes on testing your soil for pH level and certain nutrients. For anywhere from $10 – $25 you can send in less than a cup of your soil (usually to a state university extension office) and receive results in the next few weeks on present levels of nitrogen, phosphorous and potassium (the NPK of virtually all plant fertilizers – good nutrients to have, but far from all your soil needs to optimally produce healthy plants.)
Alternately, you can look for signs in the garden itself for what the nature of your soil is like. Certain weeds grow prolifically in soils with higher nutrients, while some prefer to move in after the nutrients have been depleted. Generally healthy, fertile soils will be home to weeds such as foxtail, chicory, dandelion, lamb’s quarters and purslane. If your soil is not so healthy and has been stripped of many growing nutrients, it may have daisies, Queen Ann’s lace, plantain, ragweed, thistles or crabgrass.
It’s amazing that nature itself can tell us so many things about the very ground we walk on and eat from, if we will
only take a little time and effort to get to know it. God’s creation is living, breathing and organic in its very nature.
And red cabbage is no exception.
Red cabbage has a component called flavin, which changes colors
depending on the acidity present. Bright red indicates high acidity (lower than 7, getting closer to 0 on the pH scale); greenish yellow means a high alkaline content (above 7 and nearing 14 on the scale); while a purplish blend of blue or red indicates a fairly neutral soil pH.
To illustrate this, I mixed equal parts cabbage water with white wine vinegar. You can see the before-and-after difference.
If you can boil water, you can do this experiment.
First you chop up about 2 cups of red cabbage, place it in a pot and cover with water. Boil. Remove from heat to cool to room temperature.
While your water is cooling, go outside and gather some soil. About 1 tablespoon of soil from
however many areas you’d like to test. I gathered samples from my newly-planted strawberry bed, a bed I made last year and have grown vegetables in, some buckets of soil I brought home from a community garden dirt pile, and from a bag of potting mix.
Mix each of the samples with a splash of water (distilled is best, for its neutral pH – I used some tap water I let sit out over night so the chlorine could evaporate off.)
Only the potting soil showed an immediate color change (and in hindsight, I believe this was because the components of the potting soil were mixed so as to slowly take up and release water, which slowed the absorption of the cabbage water – good for new seedlings so they don’t become water-logged, bad for proper test results.)
The next morning however, each soil sample showed a deep turquoise tint to the brown water they were initially. Meaning I’m fairly confident that my garden soil falls within the very acceptable-to-plants neutral range on the pH scale.