Fertilization and Irrigation Considerations for Container-grown Nursery Crop Production
Controlled-release fertilizer (CRF) is currently used in containerized nursery production to improve nutrient use efficiency and reduce run-offs. However, specific strategies involving the improvement of nutrient management for environmental and economic reasons are still needed. The objectives of this study were: 1) to determine the optimal CRF top-dress rates to reduce production time of two flowering shrubs; 2) to investigate the influence of irrigation regimes, based on substrate water volumetric capacity, on plant growth and nutrient leaching; 3) to determine the rate of release from incorporated CRF placed in storage. Results of this study show that a top-dressing application range of 10.0 to 15.0 g N/pot for both Hibiscus and Hydrangea can improve plant quality and flowering time. Spirea shrubs irrigated at 0.35 m3･m-3 had best overall growth and reduced N leaching while Hydrangeas performed best under rate 0.75 kg N･m-3. Stored CRF-incorporated substrate for 10 days did not reach concerning levels for moderate to high salt tolerant plants; however N release began 24 hours after incorporation. Consumer potting mix stored for six months did not exceed 1.0 mS･cm-1.