The Oregon Garden Wetlands
Barley Straw Algae Control Research

by Deborah Hill and Renee Stoops
Photos by Peter Marbach - Click to enlarge

SPROut (Sustainable Plant Research and Outreach) collaborates with research entities to conduct research on site at The Garden. Dr. Patrick Hayes from Oregon State University has been investigating the possible benefits of barley straw to control algae. Algae growth often creates a problem in water that is influenced by wastewater or non-point source pollution and is especially unsightly in ornamental water features, including The A-Mazing Water Garden on site here. <<
  Barley straw shows promise for controlling algae bloom in freshwater systems. It boasts a particularly successful record in the British Isles, where most of the research and use has occurred (Geiger et al. 2005 citing Barrett et al. 1999). Barley straw use in North America has been less successful, for reasons that are not fully known (Geiger et al. 2005 citing Nichollas et al. 1995, Lembi, 2001, Boylan & Morris 2003). 

Although we don’t know exactly how barley straw works to limit algae bloom, researchers believe it may have something to do with the release of phenolic compounds (lignin) and oxidized phenolics as the straw decomposes (Geiger et al. 2005 citing Everall & Lees 1997, Pillinger et al. 1994, Ridge & Phillinger 1996). Another hypothesis states that as the straw decomposes, it releases carbon. Then carbon-limited microbe populations expand, taking up more phosphorous. This in turn limits the amount of phosphorous available for algae (Geiger et al. 2005 citing Anhorn 2005). The effects of barley straw have not been the same over all algae taxa; some taxa respond, some do not, and some results are inconclusive.

Investigators identify five factors that affect the success of barley straw treatment for algae growth in natural waters (Geiger et al. 2005) for specific dosages please see the source:

1) Barley straw should be placed in the body of water several months before bloom conditions are expected to occur. This is because straw decomposition must proceed for some weeks before significant algae-suppressing substances are released. In addition, it has been found that even very high doses of straw cannot eliminate a bloom once it has begun. Under British conditions bloom suppression continues for up to six months after straw is placed in the water.

2) An adequate amount of barley straw must be used. This is normally specified in weight of dry straw per unit area or dry straw per unit volume of the body of water.

3) The barley straw must be well-aerated. Therefore bales of straw should only be used in streams with strong currents. Otherwise the straw is usually packed loosely in netting, best configured as long tubes that permit good water flow through the straw and that can be arranged to cover an extended area.

4) The straw must be kept near the water surface, usually by attaching floats to the netting.

5) Distribution of the straw must be reasonably uniform over a large body of water.
Filamentous algae growth poses a problem on our large water wall -- both in the trough and the wall face -- and also in the pond cells of the A-Mazing Water Garden. Treatment before we used barley straw consisted of skimming, power washing, hydrogen peroxide, and supplemental beneficial bacteria. We put barley straw in the waterwall trough June, 2004, and during that summer treatments included barley straw, hydrogen peroxide and shutting off the waterwall one night per week (to dry out the algae on the waterfall rock face).  

In March 2005 we placed four bales of barley straw of 40 pounds each under the bridge in the A-Mazing Water Garden. We removed these in April and put them into straw sausages along with new straw. Then we tied them with jute and placed them in the trough above the waterwall. In June we added 40 more pounds of straw sausages to the trough. We noticed a decrease in algae growth during the time of barley treatment, and we haven’t had to use hydrogen peroxide or supplemental bacteria since. 

References:

Geiger, S., Henry, E., Hayes, P., Haggard, K. 2005 Nov 1. Barley Straw-Algae Control Literature Analysis.
Hayes, P., Geiger, S., Haggard, K. 2005. Barley straw for algae control-Phase II. Agricultural Research Foundation, Final Report.
Starner, S. 2006 Jan. Water Quality Division Supervisor, City of Silverton. Personal communication. 

The Oregon Garden Wetlands
Wetland Research | Water Quality Research

The Oregon Garden Web Site

WGI ONLINE Journal Table of Contents

Water Gardeners International
Home | Join WGI | Members' Exclusive | Gateway to Water Gardening