[gardenfelder]

While not stated in the piece, it's not unlikely that there are other factors involved in the reduction of fertilizers. This is a wildly complex situation:

On the one hand, modern agriculture has learned that you can increase crop yields through the use of heavy fertilizers, which lead to decreased soil capabilities, which lead to increased pest issues which lead to increased use of pesticides which leads to... a truly vicious circle, one quite profitable for the likes of monsanto

On the other hand, there is an emerging technology which, in the long run, is not emerging at all, but much closer to a return to agriculture's roots - it's known as Regenerative Agriculture - sometimes referred to as "no-til" farming. The idea being that you, quite literally, improve soil's ability to capture and retain carbon - something you give up when you plow the soil - and, from there, you reduce the amount of water needed, improve soil health, and measurably improve crop yields. There's a strong movement in that direction, and several feature-length films. A brief intro is found here: https://www.youtube.com/watch?v=V6m-XlPnqxI

[gardenfelder]

Brief update, regenerative ag was mentioned in a nearby HN piece:

https://news.ycombinator.com/item?id=32203620

[knubie]

The article specifically mentions that this new regulation does not limit fertilizer use itself, so the motivation seems to be entirely driven by climate change and not soil sustainability.

[loonster]

I would feel much more comfortable with subsidizing more sustainable practices than the hard handed approach of forcing a great leap forward.

[7speter]

You seemed to have left out the runoff from fertilizer that can throw ecosystems off, a prominent example are algal blooms