I’d just add more well rotted manure or anything else well rotted, cover it & wait til tge spring, although you might want to do a ph test, it might need some lime to help it, think I read in Johns guides (look on home pages) about lime helping plants take up the nutrients. So you’d have to apply lime & manure judiciously as you shouldn’t put them down together.
The science of it is that the lime reacts with the nitrogen compounds in the manure causing the release of ammonia, which is a gas so is lost to the air and therefore your soil.
I have also read that because ammonia is also highly soluble in water, if the reaction takes place in the soil the ammonia is captured by the soil water and subsequently recycled back into nitrates.
On that basis, spreading the lime on top of the manure would be the worst plan, manure on top of the lime should minimise the problem, and digging them both into the soil the best.
I'm not desperate to go against the conventional wisdom on the subject so I'll let you decide!
I have also been advised to only add manure every 3/4 yrs, I do carry out PH tests and add lime every year.