2017 ASHS Annual Conference

Calcined aggregates from shale (haydite) and clay (turface) were investigated for use as substrate components blended with composted pine bark for the production of container-grown woody ornamentals. Volumetric ratios of 5%, 10% or 15% of haydite or turface were blended with remaining percentages of composted pine bark to create different container substrates to compare with a control substrate of 85% composted pine bark:15% peatmoss (vol:vol). Hydrangea arborescens L., H. macrophylla (Thunb.) Ser., Physocarpus opulifolius (L.) Maxim. and Viburnum nudum L. were grown in the substrates for one growing season. Growth index, substrate volumetric moisture content, and leachate pH, electrical conductivity and nitrogen and phosphorus concentration were measured during the growing season. Samples for foliar nutritional analysis were taken in November and final dry weights were measured at termination. Growth index was lower for some of the haydite treatments than control for P. opulifolius and V. nudum toward the end of the growing season. Dry weights were lower for some haydite and turface treatments than control for H. arborescens, H. macrophylla and V. nudum. While growth was statistically lower for several of the treatments, the differences were not practically apparent. There were few differences in pH or EC due to treatment. There were few differences in substrate volumetric moisture content except for P. opulifolius, where all treatments were usually lower than control. Foliar analysis showed differences for all taxa due to treatment, particularly for H. macrophylla and V. nudum. Differences in foliar nutrition resulted in visible symptoms for H. macrophylla, most likely due to lower magnesium content. However, nutrient content was higher for several elements for H. macrophylla, P. opulifolius and V. nudum. Although there were visible nutrient deficiency symptoms for one taxa and some minor reductions in growth for several taxa due to treatments, the calcined aggregates should be suitable components for use in pine bark based substrates for woody ornamental container production.