Micronutrients - trace elements, salts etc. that plants need. Again, it is important to understand that not so much the total amount in a given volume of earth is interesting but the amount actually available to a plant (Mg tied up in the middle of some rock won't help). I think these cycle like macronutrients, but the slow breakdown of sand and rock is also an important source. But this is a slow process. On intensivly used fields, these will be added in addition to fertilizer. This gives you a hint that the processes supplying micronutrients happen slowly.
So if you think of soil as the sum of these three categories you can look at how fast or slow each is replenished and used. FArmers will watch for the nutrient balances as well as for the carbon balance of their fields.
However all of these influence each other, soil is really complex. While you can argue that soil is renewable since in some cases all three broad categories of stuff will be replenished eventually, IMO this misses the point how slowly this happens. It also misses the more important point that soil is not simply a mixture of stuff but ideally a living system where things happen.