manuring bed

i am planning on putting manure on some of my beds this weekend. im a new comer to allotments so hear goes. if my manure has straw or wood shavings mixed with it does it steal all the nitrogen. i am planning on putting it direct onto the beds and leaving the worms to take it down for me. should i cover the beds once manured with plastic or weed supressant or leave it for the frost and weather to get at it?

Sometimes the wood chips stay around for a while but you can just fork them in in the spring