Submitted to: Applied and Environmental Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 15, 2009
Publication Date: October 1, 2009
Repository URL: http://parking.nal.usda.gov/shortterm/21163_Sucrose_paper.pdf
Citation: Blank, R.R., Young, J.A. 2009. Plant-Soil Relationships of Bromus tectorum L.: Interactions among Labile Carbon Additions, Soil Invasion Status, and Fertilizer. Applied and Environmental Soil Science. Volume 2009:1-7. Article ID 929120. Interpretive Summary: We quantified how the growth of the invasive grass, cheatgrass, was affected by soil type and its interaction with sucrose application, which immobilizes soil nitrogen. Soil previously noninvaded by cheatgrass had an inhibitory factor that was absent in soil invasive by cheatgrass for several years. The inhibitory factor could be reduced after several growth cycles and more quickly when sucrose was applied. Sucrose application reduces the growth of cheatgrass, but immobilization of soil nitrogen is but one factor and we suspect that pathogenic microorganisms are encouraged by sucrose. Greater understanding of the inhibitory nature of noninvaded soil may lead to new control strategies for cheatgrass.
Technical Abstract: Invasion of western North America by the annual exotic grass Bromus tectorum L. (cheatgrass) has been an ecological disaster. High soil bioavailability of nitrogen is a contributing factor in the invasive potential of B. tectorum. Application of labile carbon sources to the soil can immobilize soil nitrogen and favor native species. We studied the interaction of labile carbon addition (sucrose), with soil invasion status and fertilizer addition on the growth of B. tectorum. Soils were noninvaded (BNI) and B. tectorum invaded (BI). Treatments were control, sucrose, combined fertilizer, and sucrose + fertilizer. The greenhouse experiment continued for 3 growth-cycles. After the 1st growth-cycle, sucrose addition reduced B. tectorum aboveground mass almost 70 times for the BI soil but did not significantly reduce growth in the BNI soil. B. tectorum aboveground mass, after the 1st growth-cycle, was over 27 times greater for BI control soils than BNI control soils. Although sucrose addition reduced soil-solution NO3--N, tissue N was not significantly lowered, suggesting that reduction of soil available N may not be solely responsible for reduction in B. tectorum growth. Noninvaded soil inhibits growth of B. tectorum. Understanding this mechanism may lead to viable control strategies.