Effect of fertilizer nitrogen on weed emergence and growth

Amy E. Sweeney, Karen A. Renner, Carrie Laboski, Adam Davis

Research output: Contribution to journalArticlepeer-review


The timing of nitrogen (N) fertilizer application may influence germination, emergence, and competitiveness of weeds. Research was conducted to determine the influence of total inorganic soil N (Nit) on the germination, emergence, and growth of five weed species. In a greenhouse experiment, seed of five weed species were exposed to four levels of N, and seed germination was measured. In the field, urea ammonium nitrate (UAN 28%) was applied at multiple rates at three spring timings, and Nit, weed emergence, and growth were measured for 21 to 35 d after application (DAA). Germination of the four dicotyledonous and single grass species was not stimulated by 450 ppmw of N compared with the untreated control. In the field, Nit of 112 or 168 kg N ha-1, measured at 7 and 21 DAA, was always greater than Nit in the untreated control. The duration of the available N pulse in the upper 8 cm of soil was dependent on N application rate and timing. At 8 to 16 cm of soil depth, Nit was greater when 168 kg N ha-1 was applied compared with no N at 21 and 35 DAA in 2004. Emergence of common lambsquarters increased as N application rate increased for each application date in 2003, but not in 2004. Emergence of ladysthumb increased with N application rate for the April 15, 2003, date; emergence of giant foxtail increased with N application rate for the April 6, 2004, date. Weed biomass was always greater when 168 kg N ha was applied compared with no N, and at four of six N application dates, when 112 kg N ha-1 was applied. This research shows that spring N fertilizer applications increase Nit and weed growth, but the influence of N on weed emergence is dependent on the weed species, seed source, and environmental conditions.

Original languageEnglish (US)
Pages (from-to)714-721
Number of pages8
JournalWeed Science
Issue number5
StatePublished - Sep 2008
Externally publishedYes


  • Dormancy
  • Integrated weed management
  • Nitrogen fertilizer
  • Nitrogen timing
  • Seed germination
  • Soil fertility
  • Weed growth

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Plant Science


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