Compost is not so much a fertilizer as a soil builder. It buffers disease and with the organic matter in it, increases the holding capacity of sandy soils and helps clay soils be less stiff and sticky. All soils benefit from compost, and I don't believe you could hurt any plant by its application.

Indeed, if one were to subject their compost to a chemical analysis, some very low levels of the big 3 nutrients would be observed. So yes, it could be considered a fertilizer...if that's the purpose for which you are using it. But Lacy's example is closer to the truth-it is always and everywhere a soil amendment. We don't tend to believe in amending the backfill when planting plants, but amending large areas can be helpful in boosting soil microorganims that go on to produce further benefits. When spread on top of the soil surface, and perhaps then covered with an uncomposted organic material, like wood chips or bark, you're getting the double whammy of soil improvement plus the mulch benefits.

There is but one way that I'm aware of where a person can use too much compost: Compared to our field soil in this area, which is clay-based, compost is very light and airy. So, let's say you replace all the field soil in some planters or other with straight compost. It may tend to dry out too fast. Since it is so well aerified, it does tend to dry very quickly. If your field soil is sandy, then adding compost will improve moisture retention, so to some extent, it depends on what material you're starting out with. I use compost in my ornamental plantings and it's made a huge difference. But i wouldn't use it in the same manner for trees and shrubs. For those, it's either modify large areas or just leave well enough alone. I do like the gradual improvement though of using such materials as top dressing.

trees dont need compost or fert ... a mulch would be much better ... and though compost can be used as a mulch ... it will probably be gone by late summer ... it will just disappear ...

as a soil builder .. you benefit much more.. by using it in a veg garden ...

unless your soil test shows something is lacking from the soil ... fert just isnt needed for trees ...

the most important thing for you trees and conifers.. the first 2 or 3 years .. is proper water management ... not food ... and after such.. if you fert your lawn .. and they are near your lawn ... they will get the roots to such

ken