Reduced rates of controlled-release fertilizer lower potential nitrogen leaching from a Wisconsin bare-root tree nursery

Abstract

Controlled-release fertilizer (CRF) typically increases nitrogen (N) fertilizer uptake and lowers N lost from the rooting zone via leaching. However, questions remain as to whether lower rates of CRF could further increase this efficiency, especially in sandy bare-root nurseries in Wisconsin. We hypothesized that: 1) a reduced CRF application at 60 percent of the conventional rate (CRF60) would yield similar seedling morphology and biomass compared to a conventional application (CONV) and CRF at 100 percent of the conventional rate (CRF100); and 2) the CRF60 would result in significantly reduced potential N leaching (total N inputs minus plant N uptake) relative to the conventional rate. To test these hypotheses, we conducted a 2-year experiment in northern red oak (Quercus rubra L.) (NRO) at the largest bare-root nursery in Wisconsin. We applied a total of 259 kg N ha^-1 to the CONV (ammonium sulfate) and CRF100 (coated urea) and 157 kg N ha^-1 to CRF60 (coated urea) using standard application schedules. After two growing seasons, there was no significant difference in morphology (height, diameter, first-order lateral roots), biomass (stem, roots, total), and N content (stem, root) between treatments. However, the potential N leaching decreased significantly in the CRF treatments (30 percent under CRF100, 88 percent under CRF60) compared to CONV. Net N mineralization also decreased significantly under CRF (59 percent under CRF100, 32 percent under CRF60) compared to CONV. Overall, we conclude the CRF60 treatment would maintain seedling production goals for NRO relative to conventional levels but would signifi cantly reduce potential N leaching at a bare-root nursery in Wisconsin.

Parent Publication

• Proceedings, 17th Central Hardwood Forest Conference

Citation

Fujinuma, Ryosuke; Balster, Nick J.; Lee, Hyung-Kyung. 2011. Reduced rates of controlled-release fertilizer lower potential nitrogen leaching from a Wisconsin bare-root tree nursery. In: Fei, Songlin; Lhotka, John M.; Stringer, Jeffrey W.; Gottschalk, Kurt W.; Miller, Gary W., eds. Proceedings, 17th central hardwood forest conference; 2010 April 5-7; Lexington, KY; Gen. Tech. Rep. NRS-P-78. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station: 347-357.