A Technical Report from The Bartlett Tree Research Laboratories 409
There are many materials that are used for mulching trees and shrubs. One of the most economical is fresh woodchip mulch produced by tree pruning and removal operations. Fresh woodchips are a mixture of wood, bark and leaves. This mixture is very desirable because of its carbon:nitrogen (C:N) ratio, which is lower than pure wood-based mulches. Research data confirms no nitrogen tie-up occurs when this type of mulch is applied to the soil surface.