The Impact of Composted, Municipal Biosolid Amendments to Soil on the Growth and Nutrient Content of Rhododendron × `PJM'

Abstract

Field experiments were conducted in 1998 and 1999 to determine the effect of soil-incorporated, composted municipal biosolids on the growth and nutrient content of 30.8 cm-38.5 cm Rhododendron × `PJM' grown as containerized plants. Biosolid compost produced in Endicott, N.Y., was incorporated in May 1998 and 1999 at rates of 0, 9.8 Mg/ha and 19.7 megag/ha to a depth of 23 cm. Each treatment was replicated six times in a randomized block design. Plants were planted 10 June 1998 and 8 June 1999. Plants were harvested 10 June, 19 Aug., and 22 Oct. 1998 and 8 June and 22 Sept.1999 after which they were dried, weighed, and analyzed. During 1998, there was little difference in dry weight or nutrient content in plants harvested at the August harvest date, however, dry weight and most nutrient levels increased with increasing rates of compost application in plants harvested at the October harvest date. In 1999, no statistical differences were noted at the September harvest date in plant dry weight or nutrient content. In 1999, measured soil physical properties (water retention, bulk density, water content, and soil strength) did not differ significantly between treatments. Excellent soil structure and drainage, relatively low rates of compost application and a severe drought may have contributed to the lack of any conclusive results noted in 1999 though some positive plant responses to the treatments were evident in 1998.