ARS | Publication request: The influence of tillage and crop on giant ragweed emergence and seed persistence in the soil

Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract
Publication Acceptance Date: January 30, 2008
Publication Date: February 5, 2008
Citation: Nordby, D., Williams, M., Chee Sanford, J.C. 2008. The influence of tillage and crop on giant ragweed emergence and seed persistence in the soil [abstract]. Weed Science Society of America Meeting Abstracts. Available: http://www.wssa.net.

Technical Abstract: A long-term study of giant ragweed (Ambrosia trifida) seedbank persistence was initiated in the fall of 2002 at the Northern Illinois Agronomy Research Center near Dekalb. The study system is managed to prohibit seedbank additions, therefore focusing on seedbank losses from an initial giant ragweed population. The effects of two tillage types, conventional and no-till, are tested in both crops of a corn/soybean rotation. At the onset of the study and each succeeding fall, soil samples are collected and analyzed to determine seedbank density at depth increments of 0 to 2 cm, 2 to 6 cm, 6 to 12 cm, and 12 to 20 cm. Seedbank losses due to emergence are also monitored weekly and biweekly from early April until no further emergence is detected every year. Emergence of giant ragweed from the plot area has been observed and ranges from 8 to 29% of the seedbank present in the soil. Tillage has had no long-term effect on persistence of giant ragweed seed in the seedbank. Differences in seed distribution due to tillage were more pronounced at the onset of the study and have since become undetectable. The number of viable seed remaining in the seedbank has decreased significantly from 2002 to 2007, with the greatest decrease in seed number between years 2002 and 2004. During this period, 98 percent of the seedbank had dissipated. Long-term evaluation of this study will be beneficial in developing tactical approaches to controlling giant ragweed and for exploring the role of microbially-mediated seed decay in seedbank ecology.