alt Hacker News> The vast majority is grown on marginal land, just above pasture.
I have no idea about the US, but in Europe it's absolutely not the case. We've replaced huge quantities of land that was twenty/thirty years ago dedicated to other crops.
Also, we could actually convert them to pastures, that have a much better ecosystemic value (or even let them grow into unexploited forests, for even better environmental effect).
> They can't grow better crops without massive works of engineering and tons more fertilizer and energy use.
Most crops in the modern world run an engineered soil anyway.
In fact, in Europe the most fertile soils have long been destroyed by urbanization (because they were where the population density was the highest in agrarian times and where the megalopolis arose).
> The "limited value" isn't so limited when we're talking about an additive to gasoline. The first thing we tried polluted the entire world with a background level of lead!
We only got there because it was promoted by denying scientific evidences for many decades. Diesel engines have their own issues but they don't require these additives and you cannot pretend they don't exist.
That's my fault, I should have prefaced that I'm just talking about the US. I have no idea what the situation is like in Europe (for some reason I assumed biofuels weren't big there). Due to US density and geography, most marginal land here wouldn't be returned to little more than pasture. It depends on the state but most of that land was never forest to begin with.
> Most crops in the modern world run an engineered soil anyway.
What do you mean by engineered? The most fertile places in the US (i.e. the southwest) run on multi-million year old alluvial plains where micronutrients are deposited from mountain runoff. NPK and some micronutrients are supplemented but the most fertile regions tend to be the least "engineered". The engineering goes into the massive irrigation projects, not the soil, precisely because engineering the latter is so much harder.