Nitrogen accumulation by conifer seedlings and competitor species from (15)nitrogen-labeled controlled-release fertilizer

• Published in: Soil Science Society of America journal Vol. 67; no. 1; pp. 300 - 308
• Main Authors: Hangs, Ryan D, Knight, J Diane, Ken C J Van Rees
• Format: Journal Article
• Language: English
• Published: Madison American Society of Agronomy 01-01-2003
• Subjects: Fertilizers; Growing season; Leaching; Nitrogen; Pine trees; Seedlings; Soils; Trees; Vegetation; Weed control
• ISSN: 0361-5995; 1435-0661
• DOI: 10.2136/sssaj2003.3000

A major impediment to the establishment of outplanted conifer seedlings is competition for available soil N by early successional species. The objective of this field study was to determine the fate of controlled-release fertilizer (CRF) N in soils with outplanted white spruce (Picea glauca [Moench] Voss.) and jack pine (Pinus banksiana Lamb.) seedlings, and the effect of weed control or vegetation management (VM) on fertilizer N accumulation. Nitrogen-15 labeled CRF was placed next to the seedling root plug during planting at four boreal mixed wood sites. After one growing season in the control plots, fertilizer N recovery as a percentage of 15N added was 4% in seedlings, 3% in competing vegetation, less than 1% leached, and 85% residual CRF. After two growing seasons, fertilizer N recovery was 15% in seedlings, 20% in competing vegetation, less than 1% leached, and 58% residual CRF. Overall, VM increased seedling fertilizer N uptake by almost 300% compared with conifer seedlings in control plots. In VM plots, fertilizer bags contained more N than in control plots after two growing seasons. In both treatments, greater than 50% of the fertilizer N remained in the fertilizer bag, presumably remaining available in subsequent seasons. Calamagrostis (Calamagrostis canadensis) was the primary competitor for fertilizer N in both growing seasons, with minor competition from fireweed (Epilobium angustifolium L.), and aspen (Populus tremuloides Michx.). The use of a point source CRF delivery method resulted in high fertilizer use efficiency (FUE), and minimized losses to competing vegetation and leaching.