Good point. Even if the soil doesn't erode via physical removal (ie. soil erosion), it still erodes by consumption of organic material by the plant or microbes, etc. Fertilizer does not add organic material to the soil.

I see this clearly on my own land between the areas previously used to grow wheat and pasture. The cultivated area is dead and reduced to clay, you could use it to build adobe style buildings; whereas the uncultivated areas are loose, dark and crumbly in comparison. Modern farming methods have destroyed the topsoil, fait accompli, for anyone looking it is black and white, no yes, buts or perhaps.

Modern farming destroys the soil. Producing biofuels destroys the soil without producing food, which is doubly destructive. It is possibly the most stupid thing humans have ever done, in a long list of really stupid things.

I have absolutely no qualms about the production and use of biodiesel done in a sustainable way. This also absolutely negates any possible argument for their mass production or use to lessen the impact of Peak Oil. It simply isn't scalable and isn't a solution to oil unavailability in regards to the current economic system.

As far as I'm concerned, we don't need new technology, new energy sources or social systems. We just need common sense, we need to use what we have sensibly and we need to get rid of the nonsense that is unnecessary. If this cannot be achieved by society as a whole, then the individual must go it alone without society.

Triumvirate of collapse - Economy, Ecosystem, Energy

Consider the effect on the soil of growing perennial grasses instead, with all the non-CHO elements returned to the soil after processing the cut grass.