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 study also indicated that it also took 3 years for mulch and compost benefits to kick in. While the other substrates had several positives, they did very little to improve the physical, chemical and biological properties of soil and tree growth - a major strength of the mulch and compost.
The complete study appeared in the October 2013 Tree Care Industry magazine and can be accessed at www.tcia.org.