Managing nitrogen additions and assessing water quality under the root zone in field nursery production

Michigan's nursery industry is localized in an area of high risk for ground water contamination. This study aims to evaluate the impact of nitrogen fertilization approaches on crop growth and nitrate-N concentration of water under the root zone, and to determine the validity and logistics of applying relative addition rate principles to nursery crops. Two nurseries were used in this study. Each nursery had two fields one growing Taxus spp. and the other growing a Euonymus spp. The fertilizer treatments were: (1) control (no fertilizer); (2) operational fertilization (based on the nurseries' current practices); and (3) relative addition rate (additions based on crop growth). Soil water below the root zone was collected after every significant rainfall event using porous cup lysimeters. Nitrate-N concentrations were found to be high when compared to other agricultural systems, reaching up to160 ppm in September. The RAR treatment reduced nitrate-N leaching in two out of the four fields. Crop growth did not differ among the treatments. Implications of the results indicate nursery management practices should be altered to improve the efficiency of fertilizer use.