Compost and Rubber Tire Chips as Peat Substitutes in Nursery Container Media: Growth Effects

Abstract

This research investigated the feasibility of using composted yard wastes, composted municipal solid waste and shredded rubber tire chips in nursery container media. Containerized Physocarpus opulifolius ‘Dart's Gold’, Forsythia × ‘Meadowlark’, Spiraea × billiardii, Juniperus chinensis ‘Seagreen’, J. sabina ‘Mini Arcade’, J. horizontalis ‘Hughes’, and Lamiastrum galeobdolon were grown in media amended with five recycled waste materials used as peat substitutes in a standard container medium of composted woodchips, peat, and sand (3:2:1 by vol). Waste materials used included three yard waste composts, one municipal solid waste compost and shredded rubber tire chips. Fifty or 100% of the peat in the standard growing medium was replaced with each amendment. Ten treatments (five amendments, each at 50% and 100% peat replacement) and a control (standard medium) were used for all seven plant species. Visual ratings, height and width measurements (crown volume), number of growing points and plant dry weights indicated that media in which 50% of the peat was replaced by an amendment produced larger plants of superior quality compared to the control. Rubber tire chips were acceptable as a 50% peat substitute for plants that prefer well-drained conditions, while 100% peat substitution with tire chips was detrimental to plant growth and performance. Use of immature compost in container media negatively influenced plant growth.