|
Harry A. J. Hoitink, The Ohio State University, Ohio Agricultural Research and Development Center, Plant Pathology; Daniel A. Herms, Pierluigi Bonello, |
How Long Do Effects Last?
The effects of a two- to three-inch layer of hardwood bark lasts well into the third year. The lignin (dark material) and waxes in bark resist decomposition, which is the reason for the long-term effect. Pine bark harvested from 20-year-old trees typically is at least an inch thick and consists almost entirely of lignin and waxes. When used as mulch, this type of bark lasts for several years. Bark from Western Ponderosa pines (decorative bark) lasts even longer. However, much of the pine bark sold as mulch today is harvested from 10- to 12-year-old trees. This thinner and younger bark breaks down more readily but still forms a good mulch that typically does not immobilize nitrogen as long as its wood content is low.
Composted manures, biosolids, and leaves decompose rapidly and should be incorporated into the soil based on fertility needs. These amended soils then should be mulched thereafter for optimum effects. The length of time that each product lasts depends on the resistance of the material to decay and how it was treated during storage. The best time for soil incorporation is in the fall.