When using arborist's wood chips (not retail bark chips) in the garden, the chips do not bind up nitrogen in the soil if you just lay them on top of the soil. Here the arborist's chips are free but you do have to take a truck load, about 10-13 cu.ft. if you are spreading them yourself. Research on this topic can be found at: http://gardenprofessors.com/new-extension-publicat… Cheers, Bracey San Jose CA