Seed traps positioned 1 to 100ensp;m into a cultivated field were used to assess the seed rain from an adjacent weedy pasture. The cultivated field was in the fallow phase of a crop-fallow rotation. Two sets of traps were used: one set contained steampasteurized soil and the other contained untreated soil from the field. Traps were left in the field for 12 months and then transported to a greenhouse where they were kept for 12 additional months. Seed content was determined by field and greenhouse emergence of seedlings. The pasture was dominated by grasses, the most abundant beingPoa pratensis,Stipa comata,Bromus inermis, andAgropyron repens. Seeds of pasture species were found in decreasing numbers in the fallow field, with few found more than 7ensp;m from the fence line in traps of both sterilized and nonsterilized soil. The fallow field was dominated by species such asSetaria viridis,Thlaspi arvense,Descurainia sophia, andSalsola kaliwhich were not found in abundance in the pasture. It was concluded that seed rain from the pasture had a significant influence on the germinable seed content of the soil of the cultivated field (at the edge only). The incursion of pasture species into cultivated land presumably has been restricted by cultural practices.
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