Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/2/2008
Publication Date: 9/21/2008
Citation: Teasdale, J.R. 2008. Role of allelopathy in the stimulatory and inhibitory effects of hairy vetch cover crop residue in no-tillage sustainable production systems [abstract]. 5th World Congress on Allelopathy. 84:57.
Technical Abstract: Cover crops can provide multiple benefits to sustainable cropping systems including building soil organic matter, controlling soil and nutrient losses from fields, moderating radiation and moisture exchange, releasing nutrients for subsequent crops, and suppressing weed and pest populations. Many of these benefits are particularly important for no-tillage systems where cover crop residue interacts directly with nutrient, moisture, and weed/pest dynamics at the soil surface. Hairy vetch (Vicia villosa Roth) is a winter annual legume cover crop that has been the subject of extensive research on its capacity for providing nitrogen to subsequent crops as well as its weed suppressive capabilities. The potential of hairy vetch for promoting crop growth also can result in the promotion of germination and emergence of selected weed species responsive to inorganic nitrogenous compounds. In addition, surface vetch residue can create “safe sites” for both crops and weeds by maintaining more uniform soil moisture and moderate temperature under hot, dry conditions. However, high levels of hairy vetch residue also can inhibit weed emergence by attenuating environmental cues required for germination, by physically interfering with the upward movement of the emerging seedling and the downward penetration of light, and by releasing phytotoxic allelochemicals. Allelopathic compounds appear to be released into soil only during the initial phases of residue decomposition, primarily from leaf tissue, and appear to only contribute to weed suppression for a couple of weeks. Research has shown that phytotoxins may be more effective at suppressing weeds when combined synergistically with the etiolating influence of a surface mulch; this is a potentially important area for future investigation. As a result of these multiple stimulatory and inhibitory effects, it may be difficult to predict weed suppression by a leguminous cover crop such as hairy vetch. Clearly, more research is needed to optimize management of these complex interactions to selectively promote crop production and limit weed interference.