Green ammonia is already being commercially deployed by folks like Talus. Yes, we'd have to invest hard in renewables and nuclear, but it's absolutely achievable. Ammonia production is whole integer percent of global energy use, that's not an impossible number to supply with hydrogen.
Additionally, pulse crop rotation is increasingly being used to provide some free nitrogen to the soil.
Bioreactors with Azotobacter vinelandii are showing promise in providing nitrogen fixing in a reactor.
And like, industrial composting produces fertilizers with plenty of nitrogen. Soybeans, in particular, need no nitrogen inputs and produce plenty of both useful food and nitrogen containing plant matter.
Our wastewater also contains tons of nitrogen, both from biosolids and from agricultural runoff. These are difficult to get at safely, admittedly, but not impossible.
If you pause to think about it, all that manure needs to come from feedstock plus other inputs (water, etc). If you diverted that same feedstock into producing fertilizer (in the case of soybeans) or not producing at all (in the case of dent corn) you'd have plenty of material and a reduced demand. Manure doesn't just magically come from no inputs.
Additionally, pulse crop rotation is increasingly being used to provide some free nitrogen to the soil.
Bioreactors with Azotobacter vinelandii are showing promise in providing nitrogen fixing in a reactor.
And like, industrial composting produces fertilizers with plenty of nitrogen. Soybeans, in particular, need no nitrogen inputs and produce plenty of both useful food and nitrogen containing plant matter.
Our wastewater also contains tons of nitrogen, both from biosolids and from agricultural runoff. These are difficult to get at safely, admittedly, but not impossible.
If you pause to think about it, all that manure needs to come from feedstock plus other inputs (water, etc). If you diverted that same feedstock into producing fertilizer (in the case of soybeans) or not producing at all (in the case of dent corn) you'd have plenty of material and a reduced demand. Manure doesn't just magically come from no inputs.