It is spring as I write this and all the horticulturists are getting upset at folks calling soil dirt. While I usually use the term soil myself, this is strictly a snobbish convention rather than a meaningful separation of terms. Let’s take a real look at dirt vs. soil.
“Soil” comes from the Old French word soilier meaning land, area, or place. Other comparable words are earth, mould, or dirt. “Dirt” on the other hand came from Middle English and means feces. You can trace the meaning back to a number of similar terms in the Germanic languages. The origins for what soil and dirt mean is pretty far apart. Meanings do shift over time and at some point these came to mean the same thing. This is shown by the simple translation of soilier as being dirt. You can easily argue that it is in fact the best translation of compared to the other terms given.
The fact that they are interchangeable for more definitions than just the stuff that we grow plants in is more evidence for the equity of the terms. Have you ever heard that someone soiled their trousers or a baby soiled its diaper? Then you know what I am talking about! There is a difference though, when we talk of something being soiled, we are trying to pretty it up a bit. There is an effort to try and make the language hide the offensive nature of being unclean.
Where this linguistic tidying up comes from is not clear, but it likely goes back to the centuries when the royalty of England were from France and spoke French as a ruling language. If you look at pig vs. pork, sheep vs. mutton, and cow vs. beef you will notice a distinct pattern. The animal as taken care of by the poor native farmer is called by an English name, and as eaten by the rich ruling class it is called by the French name. I believe this is why dirt gets such a poor rap. It is a word from what was the poor, subjugated, working class language.
It still surprises me that such a strong influence from so long ago is still in effect. But it matches the general pattern for English speakers. We prefer French derived words as being the superior choice. Ironically, the top way for improving fertility has been to add manure (feces) to the ground! Maybe it is time to just call dirt dirt and take care of whatever you have as best you can.