Fabric Containers Increased Irrigation Demand but Decreased Leachate Loss of Nitrogen and Phosphorus Compared With Conventional Plastic Containers During Production of Dwarf Burford Holly

Fabric containers (FAB), due to their root-pruning properties, can be used as an alternative to conventional plastic containers (PLA) in container nurseries. Because sidewall evaporation in FAB has been shown to reduce container sub-strate temperatures, our objective was to determine if FAB would reduce the release rate of controlled-release fertilizer (CRF), resulting in less leachate loss of nitrogen (N) and phosphorus (P) and greater CRF longevity. Dwarf Burford holly were grown in 36-cm-diameter (18-L substrate) FAB or PLA in a bark-peat sub-strate with incorporated CRF. Spray stake irrigation was routinely adjusted to a target leaching fraction of 25%. Maximum daily substrate temperature, measured 3 cm from southwest-facing container wall, averaged 6 degrees C lower in FAB than in PLA. For two 31-week experiments where leachate was continuously collected and sampled weekly, FAB reduced leachate N loss by 30% and P loss by 47% despite requiring 66% more irrigation water and collecting 31% more leachate than with PLA. FAB reduced average N loss from 114 to 78 kg.ha(-1) and average P loss from 16.0 to 8.6 kg.ha(-1). FAB increased plant size by 8% and shoot dry weight by 12% for one experiment but had no effect in the other. We concluded that compared with PLA, the use of FAB can decrease leachate loss of N and P but require considerably more irrigation water to offset water loss via sidewall evaporation.