A new study on the effects of barley straw has shown that is not particularly effective at controlling all nuisance algae.
The report, which is due to be published in the November issue of the journal Bioresource Technology, showed that barley straw liquor only worked well on three of 12 common nuisance algae in freshwaters.
A team of scientists from Hood College, the University of Maryland and the Morgan State University Estuarine Research Center, conducted bioassays to determine the effects of barley straw upon 12 species of common nuisance freshwater algae.
While the straw liquor did inhibit the growth of three algae (Microcystis aeruginosa, Synura petersenii and Dinobyron sp.) the growth of some other species (Ulothrix fimbriata, Scenedesmus quadricauda, Chlorella vulgaris, Anabaena flos-aquae, and Synedra sp.) did not show any significant difference.
"The presence of barley straw extracts actually appeared to cause some algae to grow much faster..."
Somewhat surprisingly, the presence of barley straw extracts appeared to cause some species of algae (Selenastrum capricornutum, Spirogyra sp., Oscillatoria lutea var. contorta, and Navicula sp.) to actually grow much faster.
The team said: "In a related field study, we treated four of six ponds with barley straw and monitored their chlorophyll a levels for one growing season.
"While phytoplankton populations in all ponds decreased in midsummer, the phytoplankton biomass in treated ponds did not differ significantly from that of control ponds, suggesting that the application of barley straw had no effect on algal growth in these systems."
For more details see the paper: M.D. Ferrier, B.R. Butler, D.E. Terlizzi and R.V. Lacouture (2005) - The effects of barley straw (Hordeum vulgare) on the growth of freshwater algae. Bioresource Technology, Volume 96, Issue 16 , November 2005, Pages 1788-1795.