Location: Application Technology Research Unit
Title: Fertilizer applications for container-grown ornamental tree production Authors
Submitted to: Journal of Environmental Horticulture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 25, 2012
Publication Date: June 14, 2013
Citation: Zhu, H., Zondag, R., Merrick, J., Demaline, T., Jeon, H.Y., Krause, C.R., Locke, J.C. 2013. Fertilizer applications for container-grown ornamental tree production. Journal of Environmental Horticulture. 31(2):68-76. Interpretive Summary: Optimal management of nutrients relies on irrigation practices, fertilizers, potting substrate contents, and species. There are so many variables that affect the tree growth. Even the same species with the same nutrient management, but grown in different locations, can have different growth rates. Because of vast varieties and species, scientific guidelines are lacking for growers to improve their nutrition practices based on their specific production circumstance. Fertilizer practices with topdressing, incorporating and liquid feeding methods can cause substantial labor cost and excessive nutrient runoff loss. To provide solutions to this problem, this research compared various fertilizer practices and nutrient applications by determining the Acer rubrum growth (caliper, height, canopy size, foliage density, leaf color and root systems) in above- or below-ground containers. The comparison also included irrigation practices for trees with buffered pond or city water, and fertilizer practices with fertigation and with the potting substrate that had nutrients incorporated, topdressed or both with slow-release granular fertilizers. Test results demonstrated that shortening tree production time and saving labor costs could be achieved by maximizing the one-year growth of container-grown trees through the optimal fertilizer practices.
Technical Abstract: Knowledge of better utilization of nutrients during the growing season is needed to produce marketable container-grown ornamental shade trees economically. Fertilizer practices to grow Acer rubrum ‘Red Sunset’ trees in two separate fields (each containing four plots) irrigated with either city or pond water were tested to compare the tree growth in a commercial nursery. There were 16 different treatments in each field, and both fields received the same 16 treatments. Two slow-release granular fertilizers (18-5-12 and 12-0-42) were applied separately or jointly as incorporation, topdress or both to potting substrate for trees grown in 26 L (7 gallon) containers placed either above or below ground. Trees receiving pond water also received supplemental liquid nutrients throughout the growing season along with nitric acid to lower the pH of the potting substrate. Tree growth was assessed by measuring stem diameter (caliper), height, canopy size, leaf color and root. Trees treated with the 18-5-12 fertilizer and irrigated with either pond or city water had significant higher caliper increases than those treated with the 12-0-42 fertilizer. Trees with the topdressed 18-5-12 fertilizer in pond water irrigation plots had significantly higher percent increases in caliper than those with the incorporated 18-5-12 fertilizer. With the same slow-release fertilizer applications, trees receiving pond water with supplemental nutrients had greater percent increases of caliper, larger canopy areas and better root systems than those receiving city water, but the differences in tree height increase were not as great as the caliper increases. However, maintaining higher tree growth in pond water plots required additional inputs with extra nutrients and labor costs throughout the growing season.