Growth and Elemental Content of Slash Pine 16 Years after Treatment with Garbage Composted with Sewage Sludge
- E. J. Jokela *,
- W. H. Smith and
- S. R. Colbert
Landspreading of organic wastes remains an environmentally acceptable option for recycling nutrients. This study assessed tree growth and elemental tissue concentrations in a slash pine (Pinus elliottii Engelm.) plantation treated 16 yr previously with four rates (0, 112, 224, 448 Mg ha−1) of municipal garbage composted with sewage sludge. Tree growth was significantly greater where garbage compost was applied. Stem wood biomass increased from 55.7 to 94.7 Mg ha−1, a 1.7-fold increase over the control for the heaviest garbage application rate. Annual tree basal area increment responses were also largest and most long-lasting (up to 9 yr) for the 448 Mg ha−1 rate. Significant but modest treatment associated increases in concentrations of N, P, B, Fe, Al, and Zn in pine tissues (foliage, stem wood), and P and Ca in Rubus spp., a dominant understory plant, were found after 16 yr. Analysis of pine xylem tissues corresponding to the juvenile and post-crown closure growth phases revealed significantly higher concentrations of K, Ca, Mg, Cu, Al, and Zn in the latter period. Results suggest that landspreading and recycling degradable organic wastes in forests can increase tree and understory growth without long-term deleterious ecosystem effects. The applicability of these results to a typical community in a forested landscape is illustrated.
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