The other comment is probably right, that this varies widely, but getting a vague order of magnitude is still useful. From some amateur googling, it seems that an acre requires on the order of 100 lbs/year (50-300lbs, though the higher figures seem to also include things other than just nitrogen/ammonia).

So 1 ton/day (assuming metric tonnage), would be in the range of 8000 acres/year, though with obviously large error bars.

This being about 32km^2, combined with this: https://worldbuilding.stackexchange.com/questions/9582/how-m... and ignoring the "round-robin" nature of the per-day restriction, it seems this might help to feed 50,000 people per such installation

> A 200-bushel corn crop requires about 200 to 250 pounds nitrogen per acre.

So that’s about 240 lbs per acre of anhydrous ammonia.

https://www.rs.uky.edu/soil/calculators/mult_fert.php

depends on the soil, current crop and the previous crop, ground cover.

For example, farmers grow beans/legumes because they are nitrogen fixers. This reduces the need for fertilisers later on. However does mean that you might bot be able to grow as profitable crop in that time.

Soil health also comes into it. An allotment will be a shittone more productive per unit area than high grade arable land

This will depend entirely on the requirements of the crop. You won't get a generic answer per unit area.

It also depends on soil properties.

However, 100-200 lbs of fertilizer per acre is somewhat reasonable, so it’s probably on the order of 10-100 acres per ton of nitrogen atoms.

Source (this is an article about measuring available nitrogen, and their examples are in the 100-200 lbs per acre range):

https://www.agry.purdue.edu/Ext/corn/news/timeless/AssessAva...