Depends on the soil they grew in but like all fruit they will have varying amounts of N, P, K, Ma, Mg, Z, Fe, Ca, etc. It would be difficult to even guess how much without a good nutrient test.

well theres a lovely nutritional website that I have found, it may help a bit to give you an idea of what you are adding to your compost. Lets say you need a little more potassium or a trace element. well you can search for a particular food or food item and get the nutritional data, from mineral content to amino acids and almost everything inbetween. Iam still learning how to read the colorful graphs.

Here is a link that might be useful: nutrition for lemon peels

For the purposes of your compost they contain some nitrogen. Most likely the bulk of the final nutrient load of your compost will come from the leaves. Unless you are struggling with a major deficiency of some kind in your soil I wouldn't worry about it, everything you need will be there.

The main issue with vegetables, more so with fruit, and especially so with citrus, is acidity. Piles with a lot of foodstuffs tend to go acidic which slows down the composting. Commercial composters of this sort of material add lime (not the green fruit!) to the initial mix so that it doesn't go too acidic. Worth remembering if you encounter problems with the pile going rancid instead of heating up.

Also, worms may be put off by the citrus. This is crucial in vermiculture but usually not a problem with regular composting since the lemon peel will be unrecognisable by the time the worms want to move in. Just another things to worry about on those long winter nights ;)

I'd question the adding of lime part, shrubs, the organic acids in foods don't = pH

I compost large amounts of food waste that I get from store produce depts, and there has never been an issue with acidity, even when I include whole tubs of citrus scrap from a juice bar - misconception that food waste makes compost acidic, and any commercial composting operation would be wasting resources by adding lime, as the microbial action requires a slightly acidic condition and over time works to neutralize that, and lime will actually depress microbial action ... finished food waste compost is nearly always very near neutral pH

the primary problem with large amounts of food waste is moisture, as most foodstuffs are high in water, particularly things like cukes, tomatoes, and most fruits - if a compost "goes rancid", it's excess moisture/ lack of air, and requires coarse high-C "bulking material" added, which commercially is usually wood chips

and the reason worms aren't keen on citrus is because the "zest" [limonene] in the skins causes slow attack by microbial action, and it's really the microbes the worms are after, once the zest breaks down, the citrus disappears quickly

and ixnod, that site you linked has to do with human nutrition, not the bio-nutrients availabe to the micro-herd or plants - lemon peel will have a much wider range of mutrients and micro-nutrients than they would cite

Bill

As Bill points out there is no real reason to add the lime when composting citrus fruits since lime does cause loss of Nitrogen and does nothing to help your compost according to current research.

yes I wouldnt worry about adding the lime either, compost tends to neutralise itself by the end anyway so even if it does get acidic during the process it wont finish up that way. lime however is a good addition if you have a problem with maggots in the compost, I dont know exactly why this works (whether its due to the ph change or not) but i do know from experience that it does clear up a maggot problem very quickly but adding it to avoid acidity isnt necessary.