My family are farmers in Australia. We are currently going through the worst drought we have ever had. We've had 7 inches of rain this year vs our annual rainfall of 26 inches. We are still growing a (very small) crop. This is possible because of soil conservation, no-till agriculture, and having healthy soil that conserves moisture.
Farmers who haven't adopted these techniques are bankrupt.
in the US and Europe, it is possible to not engage in best practice farming techniques, because government subsidies (20 Bn USD in America, 59 Bn Euro in the EU) remove the competitive pressures that that force best practice (it really isn't as simple as 'just forcing more production out of the soil by adding more fertilizer_.
Yes, of course there are still farmers not following best practice. It's a normal distribution
If only the world were just. As you say, countries with legislature captured by farming lobbies are no longer subject to survival pressures.
Fertilizer is like doping. It works! But it comes at a long term cost. Anyway, now we can go down two paths, hyper-modern indoor farming which is expanding in Europe and organic farming that is growing in the US and Europe. Conventional industrial farming is going to get hit from both sides.
Also, the big things keeping corn going is sugar duties and ethanol subsidies. Without those, alot of the crop would disappear.