Assessing Alternative Organic Amendments as Horticultural Substrates for Growing Trees in Containers1

Abstract

Abstract Conventional substrates for nursery plant production typically are soilless media that are comprised of low bulk density material with either organic or synthetic components. These mixes aim to provide a lightweight medium that provides acceptable water holding capacity and nutrient retention and create a suitable environment for root proliferation and biomass growth. In an effort to identify alternatives to traditional container substrates, a comparative amendment study was conducted to observe changes in media qualities and plant growth response of Aronia melanocarpa ‘Viking' and Acer saccharum over a period of 16 months. Materials used to amend traditional medium included composted green waste, biosolids and wood chips, biochar, aerated compost tea and vermicompost. The results of this study found that all amendments performed equally as well as control (NULL) treatments for root, shoot and total biomass production for both Aronia melanocarpa ‘Viking' and Acer saccharum. After a period of 16 months, significant changes in biochemical properties had occurred in mediums amended with biochar, wood chips, composts and biosolids. This study provides data on a variety of alternative materials that can be used as substitutes for traditional greenhouse medium in production of nursery tree stock. Index words: aerated compost tea, biochar, biosolids, carbon to nitrogen ratio, compost, dissolved organic carbon, electrical conductivity, fertilizer, microbial biomass carbon, control, active carbon, microbial respiration, leaf fluorescence, soil water tension, total nitrogen, total organic carbon, volumetric water content, wood chips, water holding capacity. Species used in this study: ‘Viking' black chokeberry [Aronia melanocarpa (Michx.) Elliott]; sugar maple (Acer saccharum Marshall).