Black Polyethylene Mulch Increases Survival and Growth of a Jeffrey Pine Plantation

Among site factors, available moisture is often most limiting to successful establishment of conifer plantations, especially in areas of the West where very little precipitation is received during the growing season. Several methods of reducing the critical firstyear drought loss have been tested (Hunt 1963; George 1965) ; among these are mulches. Mulches tested range from conventional materials, such as straw and sawdust, to rocks (Rotty 1958; Heidmann 1963), papers (Hunt 1963; Hermann 1964), and plastic (Walker 1961). The plastic films have several uses in agriculture (Spice 1963) ; .one of their most common uses is for mulching high-value row crops. The microclimatic and edaphic effects of black plastic mulch were documented and compared to other mulch materials by Waggoner, Miller, and De Roo (1960). These workers found a dampened diurnal fluctuation in soil temperature; and they as well as Clarkson (1960), Black and Greb (1962), and Harris (1965) discovered that average soil temperatures were slightly higher under black plastic mulch than under the surface of bare soil. The nitrate content of plastic-covered soil also is much greater than that of bare soil (Waggoner et al. 1960; Clarkson 1960; Black and Greb 1962). Probably the most important value of the plastic for nonirrigated crops is that it retards evaporation (Lippert, Takatori, an Whiting 1964), thus conserving soil moisture for later use by the desired plants. The reflected or outgoing radiation is about the same, whether soil is bare or covered with black plastic, hay mulch, or dusty translucent plastic (Waggoner and Reifsnyder 1961) ; hence, the transpiration rate should not show any increase due to these coverings.

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Author(s): Norbert V. De Byle

Publication: Tree Planters' Notes - Volume 19, Number 4 (1969)

Volume: 19

Number: 4