Title: Soil seed bank community structure of pastures and hayfields on an organic farm Authors
Submitted to: Canadian Journal of Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 2, 2014
Publication Date: May 7, 2014
Repository URL: http://handle.nal.usda.gov/10113/59059
Citation: Sanderson, M.A., Stout, R.C., Goslee, S.C., Gonet, J.M., Smith, R.G. 2014. Soil seed bank community structure of pastures and hayfields on an organic farm. Canadian Journal of Plant Science. 94:621-631. Interpretive Summary: Pasture management often focuses on the aboveground vegetation. A complementary potential plant community exists belowground in the form of buried seeds (the seed bank). Knowledge of how previous land use affects the seed bank in organically managed pastures would be useful in anticipating potential weed management needs. In this research, we characterized the soil seed bank of organic hay and pasture land with different management histories. As expected, some of the largest differences in seed bank composition occurred between hayfields and pastures. Annual weeds, such as shepherd’s purse and pigweed, were more likely to occur in hayfields and relatively young (less than 5 years old) pastures than in old permanent pastures (>20 years old). The younger pastures were similar to alfalfa hayfields in seed bank composition probably because of similar management history. Perennial forbs, annual grasses, and perennial grasses were more likely to occur in older, permanent pastures. Many of the other non-forage species in the seed bank could be tolerated in the vegetation or viewed as relatively useful as forage if grazed appropriately. Organic farmers should be prepared to adaptively manage weeds with different life histories depending on previous management and land use.
Technical Abstract: Understanding the composition of seed banks in pasture soils would help farmers anticipate and manage for weed problems. We characterized the soil seed bank in eight pastures and hayfields [two alfalfa (Medicago sativa L.) and two predominantly grass hayfields; two recently established and two permanent pastures] within an organic dairy farm in southeastern New Hampshire. Seed banks were sampled in the upper 5 cm of soil in each field at a point scale in 2007 and 2010. In 2010, the seed bank was characterized at the field scale by taking soil samples on six 52-m transects in each field. Seed banks sampled at the field scale in 2010 contained 66 plant species. The total number of seeds in the seed bank ranged from 1560 m-2 in grass hayfields in autumn to more than 20 000 m-2 in alfalfa hayfields in summer. Annual forbs dominated the seed bank of alfalfa fields and recently established pastures, whereas perennial graminoids dominated in one grass hayfield and the permanent pastures. These results suggest that management history affects soil seed bank composition and abundance and these effects should be considered before implementing management practices that could stimulate recruitment from the seed bank.