Evaluation of composted biosolid waste as an amendment to a standard horticultural nursery mix for container grown Callicarpa and Ilex production

Abstract: Growth of Callicarpa dichotoma (Lour.) 'Early Amethyst' and Ilex glabra (L.) 'Compacta' liners were evaluated in substrate containing 20, 40, 60, 80 and 100% composted biosolids as compared to a 3:2:1 (v:v:v) pine bark:peat:sand horticultural mix. Biosolid waste substrate amended with biosolids had higher pH, EC, nitrate, bulk density and container capacity compared to a standard horticultural nursery mix. Total porosity and air-filled capacity were greater for the control compared to substrate amended with biosolids. The effects of substrate amended with composted biosolids on growth varied for each species. Callicarpa dichotoma "Early Amethyst' liners grown in substrate amended with 20, 40 and 60% biosolid waste had greater shoot and root dry weight and a better visual evaluation compared to the control. Ilex glabra 'Compacta' liners grown in the control (standard nursery mix) had greater shoot and root dry weight and a better visual evaluation compared to any biosolid amended substrate. It was concluded that substrate amended with biosolid waste can be utilized for the container production of plants, however, its usage may be species specific.