The Effect of Wood Mulch Type and Depth on Weed and Tree Growth and Certain Soil Parameters
Katrina M. Greenly and Donald A. Rakow
Abstract: The use of wood byproducts as horticultural mulch has increased in the last decade as the horticulture industries and landscape architects have raised the public's awareness of the aesthetic and maintenance benefits to be gained from mulch use. The objectives of this experiment were to evaluate the effect that two types (chipped pine and shredded hardwood chips) and three depths (7.5 cm, 15 cm, and 25 cm) of mulch and an unmulched control would have upon: 1)' oxygen percent, moisture percent and soil temperatures; 2) growth of two thin barked trees (Pinus strobus and Quercus palustris); 3) establishment of weed populations; and 4) potential change in certain soil parameters (pH, nitrates, and soluble salts). After two years, no differences were found between mulch types, but soil oxygen levels declined (non-significantly), temperatures declined, and moisture levels increased with increasing depth of mulch. Weed density and diversity also declined significantly with increasing mulch depth. For both species, stem growth was greater with the 7.5 cm. depth of mulch than with other mulch depths or the control. Soil pH, nitrates, and salt levels were unaffected.