Evaluation of Horticulture Applications of Light Expanded Clay Aggregates

Abstract

People involved in the nursery industry continue to seek more sustainable options to implement into production regimes. This search has been provoked by environmental and economic reasons. Several areas of popular nursery production practices have been explored to reduce cost and/or decrease environmental impact. The objective of these studies was to evaluate light expanded clay aggregates (LECA) as container mulches and as a bare rooting substrate. In the first experiment, two mulch depths of LECAwere applied to the surface of substrate in container plant production as a non-herbicide weed control strategy compared to a single pre-emergent herbicide. Twenty-five Oxalis stricta seeds were applied to the substrate surface in each container pre- or post-weed control method depending on the treatment. Results indicate that HydRocks®, at a mulch depth of 2.5 cm (1.0 in.) provided successful control of oxalis when seeds were already present in the substrate but only limited control of oxalis when seeds were applied on top of mulch. There were no visual differences in plant growth between treatments in the first experiment and no statistical differences found in plant growth in the second experiment. In a second experiment to compare yield and time to bare root, Ophiopogon japonicus and Ophiopogon japonicus ‘Nana’ bare root bibs were grown in common horticultural substrates and compared to the clay aggregates HydRocks® and Profile™. Results indicate that clay materials such as HydRocks® and Profile™, when compared to conventional substrates can provide suitable yields while also decreasing labor cost by decreasing time to bare-root. In two experiments, the light weight aggregate, HydRocks® was evaluated as a rooting substrate when compared to conventional rooting substrates. The first experiment focused on large HydRocks® (0.25 in) and combinations of sand. The second experiment compared a smaller (0.18 in) HydRocks® aggregate to several conventional rooting substrates. In both experiments shoot growth, root growth, and ease of dislodging substrate particles were compared to conventional methods of producing bare root liners. While the results of cutting quality vary depending on species, these studies suggest that HydRocks® can be used as a successful rooting substrate.