Effects of Fertilizer Placement on Greenhouse Gas Emissions from a Sun and Shade Grown Ornamental Crop1

The level to which ornamental plant production impacts rising atmospheric greenhouse gas (GHG) concentrations remains unknown. Research to date has focused on developing baseline estimations of GHG emissions from plant-pot production systems and their contribution to global warming potential. To date, pot size, irrigation delivery method and fertilizer application method have been evaluated in the production of common woody ornamental crops. In this study, two perennial herbaceous plants, full-sun-grown ‘Stella D'Oro' daylily (Hemerocallis × ‘Stella D'Oro' L.) and shade-grown ‘Royal Standard' hosta (Hosta × ‘Royal Standard') (Hosta plantaginea Aschers × Hosta sieboldiana N.Fujita) were grown utilizing one of three common fertilizer application methods (dibbled, incorporated or top-dressed). Plants were grown in 3.8 L (1 gal) nursery containers in a 6:1 pinebark:sand substrate with standard amendments. Gas samples were collected in situ according to standard GRACEnet protocols weekly for five months. Cumulative emissions for both CO2 and N2O were least for plant-pot systems using the dibbled fertilizer method, regardless of species. Cumulative CO2 emissions were highest for plants fertilized by incorporation, followed by those fertilized by top-dressing. No differences were observed between N2O efflux measurements for systems fertilized by either the incorporated or top-dressed methods. Results suggest that dibbling fertilizer could significantly decrease both CO2 and N2O emission. Index words: carbon dioxide, nitrous oxide, methane, trace gas. Species used in this study: ‘Stella D'Oro' daylily (Hemerocallis × ‘Stella D'Oro' L.); ‘Royal Standard' hosta [(Hosta × ‘Royal Standard') (Hosta plantaginea Aschers × Hosta sieboldiana N.Fujita)].