> Eventually, you won't have a choice when fertiliser produced from oil runs out, becomes cost prohibitive, or is made illegal due to greenhouse gas problems

You mean, aside from the process of making ammonia using green hydrogen that doesn't use fossil fuel at all? A process that can be sustained indefinitely, using renewable energy?

The single big concern is nitrous oxide emission from bacteria in the soil, but that can be reduced by nitrification inhibitors, some of which can be produced naturally by plant roots (and likely engineered into crop plants.)

Promises of “green hydrogen” and fertiliser made sustainably haven’t panned out. I’ll believe them when I see it, but I’m not a believer in industrial farming, which is more akin to mining.