Compost tea (aerated) adds far more than N. The organic feedstocks such as fish hydrosolate, kelp extract, P source of choice, humates etc do provide a small, though statistically significant amount of nutrient, including secondaries and micros. Feed the soil not the plant. If forest soil or a decent commercial innoculant are added just before application, mycorrhizea may provide some benefit as well though they dont survive long without a host or in the aerated bath.
If you're talking a straight up compost extraction, then nutrient levels are only at what were to be found in that given volume of compost along with its associated humic substances and microorganisms. Not much nutrient at all which isn't necessarily a bad thing.
Most mycorrhizeal species don't survive the composting process.
Bacteria, protists, fungi, and nematodes found in the soil abd compost are largely beneficial and most of the nasties are killed off in the thermophilic stage if composting though one does need to regulate what goes in. Ours is plant and topsoil derived, no manures other than the potential for some critters to do their business in the compost yard.
Again, if we can't sell a large bed expansion and appropriate understudy plantings, I try to add at least some of the benefits of what said mulch/compost bed would have provided. Dealing with trees in turf in the burbs.
No arguement about mulch beds being better, just saying it can be a good thing when done right.
