Selected mechanical properties of wood produced by loblolly pine trees fertilized with sludge

The practice of using sewage sludge as a fertilizer on forestland is becoming more common and has the benefit of increasing forest productivity. This study examined some mechanical properties (bending stiffness, bending strength, compression strength, and shear strength) and density of wood produced in a loblolly pine stand that was fertilized with sludge to see whether the structural quality of the wood was affected. The number of annual rings on wood samples was also compared. Besides the three levels (0, 400, and 800 kg TKN/ha) of sludge treatment, the soil type, tree height, and growing period were also examined. Results show that the concern that sludge application may produce wood with poor mechanical quality is unfounded. The statistical analysis indicated that one application of sewage sludge in the amount up to 800 kg TKN/ha will not significantly affect the mechanical properties of loblolly pines compared to those without sludge application.