A little bit. Have you?
the stuff like converting gallons of gasoline to miles or cars taken off the road, or gallons of water to showers and bathtubs is just arithmetic.
The original estimations or measurements come from a number of sources. And there is a large variation in the numbers. The scientific papers usually include the assumptions they have to make. For instance, some of the variations in calculating water, carbon footprints or petroleum in the production of meat or crop production is based on how far back the researchers go. For instance, when they talk about water that goes into beef, do they stop at the feedlot or do they calculate the water that went into the crops that are fed to the cows. And do they just calculate the amount of water that the animals drink or do they also calculate the amount of water used to operate, maintain, and clean the feedlot? Some Feedlots also have wastewater systems that use a lot of water. But there is a lot of variation on that as well. In some places they allow wastewater to go into rivers and lakes. but some places require some kind of wastewater treatment (which also uses water).
There is the fuel used in the cultivation of a crop, then the transportation of the crop. and some things get processed and transported agian.
I'm pretty sure that gold standard of estimating water usage comes form a scientific paper that was produced in Belgium. It gets referenced a lot so it might be able to be found with just a google. Hold on a second.
Ah. here it is, I'll put a link on the bottom. (1) I have to admit that I have not read the whole thing. but a lot of the things I have read have cited this one.
Here is one that I have read. And it cites the Belgium article and a whole bunch more. (2)
A lot of the other numbers come from the The 2006 report
Livestock's Long Shadow, released by the
Food and Agriculture Organization (FAO) of the
United Nations. (3) Again its not something I have read but it gets cited a lot of times in the things I do read.
As I mentioned earlier there are a ton of variation in the numbers being reported. Sometimes its just the variation in the study themselves. but honestly I know that some reporters cherry pick the numbers they report.
But regardless of which study you want to use, or the numbers being reported, animal agriculture is mostly a very wasteful use of resources. The type of agriculture you practice is probably the least wasteful of all. but you have to admit that it represents a very small fraction of the total.
BTW, did you ever check out the Omnivore's Dilemma? The author describes a "slow food farm". It sounds like your farm.
1.
https://ris.utwente.nl/ws/portalfiles/portal/5146091/Ercin11water.pdf
2.
https://academic.oup.com/af/article/2/2/3/4638610
3.
http://www.fao.org/3/a-a0701e.pdf