A five year study to evaluate the effects of organic and inorganic fertilizers on soil quality and tree growth was recently completed by researchers at the Morton Arboretum in Lisle, Illinois.
The substrates tested were hardwood mulch, compost, aerated compost tea, synthetic NPK fertilizer and a commercial biological product (mycorrhizae). The results showed that soil compost and mulch had the most dramatic impact on soil quality. Likewise, tree growth was greatest with mulch and compost.
The injury or death of trees and shrubbery from roots girdling their stems is becoming almost as bad a problem as volcano mulching and poor pruning.
The USDA-FS recently published a list of the major causes of girdling root problems. At the top of the list was container grown plants.
Here is the rest of the list:
Plant dormancy is defined as the resting phase of a plant's annual life cycle. It's characterized by a drop-off in energy use and major plant functions (i.e. transpiration, photosynthesis, respiration, etc.,). Triggered by shortening day-length and several deep frosts, the plant dormant period usually starts in late November and ends when plant buds begin to swell in late March-early April.That's a stretch of about 4 months of relative calm for trees and shrubbery.