P-24 Elevated Soil Sand Content Enhances the Suppressive Effect of Mustard Seed Meal on Velvetleaf Growth

Buller Hall

The use of mustard seed meal (MSM) as a biofumigant in managing weeds in agricultural settings has been well documented. However it has been suggested that soil types may differ in their ability to foster the deleterious effects of the meal on undesirable plants. Work with MSM in altering velvetleaf (Abutilon theophrasti) seedling soil growth has shown that certain soils were better suited for weed suppression than other soils. The most effective soils had elevated levels of sand in comparison to less effective soils. The hypothesis that soil sand content influences the effect of MSM on velvetleaf growth was tested by adding sand in varying amounts (final soil content: 29-70%) to a silt loam soil where velvetleaf seedlings were grown short-term. The resulting pattern of growth was consistent with the hypothesis that increased sand levels correlated with decreased weed growth. Weed seed germination was reduced at the highest sand levels. Possible mechanisms of the effect of sand on MSM effectiveness will be discussed.