Barley straw for ponds does not control algae, does not reduce muck, disease-causing bacteria, odor, or weeds, and it does not improve fishing, boating or swimming. Barley straw for controlling algae was first publicized in England in the 1990s (1). CLEAN-FLO immediately performed tests on several algae-infested ponds, and water transparency did not increase. In some cases, water transparency declined. We at CLEAN-FLO believe that barley straw is neither an algaecide that kills algae nor an algae-stat that prevents more algae from growing. We believe that barley straw makes a haven for zooplankton that feed on algae, especially when the barley straw is loosely based. We believe that adding barley straw for ponds is just as unfavorable as dumping tree leaves into a lake or pond. On the contrary, it increases the biomass and nutrients available to undesirable algae, and perpetuates nutrient recycling rather than nutrient reduction.
Results at Purdue University (2) Maryland University (3) and Iowa State University (4) showed that some algae species were reduced by barley straw for ponds, while other species did not respond, or increased. Species that increased were mat-forming filamentous algae that zooplankton does not feed on.
Results at the University of Nebraska (5) showed that water quality remained poor and the lake became dominated by blue-green algae, a type of algae that zooplankton do not eat.
Studies at University of Florida (6) and at North Carolina State University (7) on pre-digested barley straw, which is supposed to increase algaecidal compounds barley straw is supposed to release while it decomposes, were unsuccessful. Algae did not decrease but remained at the same level. The University of Florida concluded that the amount of barley straw needed to control algae in ponds is too large for practical purposes.
Faulty Tests and Misinformation
Algae are the only parameter studied by some consultants as a measure of water quality. Three tests are used: 1) water transparency, a measure of the amount of algae in a lake or pond, 2) chlorophyll-a, a test of the amount of chlorophyll in algae, and 3) total phosphorus, which is the amount of phosphorus present in algal biomass. These tests do not consider the quality of a lake or pond by the amount of muck or the organic matter in muck, odor, aquatic macrophytes (weeds), disease bacteria, fish health and growth rate or number of fish, or by whether one can fish, swim or boat in a lake or pond. You can fish, swim or boat in a lake or pond if it has a lot of algae, but you cannot swim, fish or boat in a pond in which the water quality has been degraded by algae to the extent that it becomes unsuitable for recreational use. This has become increasingly common in recent years.
If a consultant can reduce algae in a lake, he or she becomes a well-paid local hero, regardless of whether or not the lake remains a viable ecosystem. Algae may be reduced, but there may be many adverse outcomes including the reduction of fish populations, accumulation of organic muck, and proliferation of weeds. This opens an opportunity for what is called biomanipulation. A faulty test of barley straw is if you kill the fish; algae will decrease because zooplankton feeds on algae and fish feed on zooplankton. If there are no fish, there are many zooplankton, so there are little algae. If there are not much algae and available phosphorus and nitrogen are still in the water, nutrients accelerate weed growth and create a nutrient stockpile in the ecosystem. This creates a self-perpetuating cycle that moves the system from one characterized by a healthy oxygen-to-nutrient balance, to one that is characterized by the reverse, or eutrophication. Lakes in this condition quickly become unusable for most kinds of recreation.
Real Pond Restoration
In summary, barley straw for ponds does not reduce muck, bacteria, odor, or weeds, and it does not improve fishing, boating or swimming. On the other hand, Clean-Flo’s approach using laminar flow inversion oxygenation and bioaugmentation has been shown consistently to address these problems successfully and economically.
- Newman, J. 1997. Control of Algae with Barley Straw. Information Sheet No. 3. Institute of Arable Crops Research, Center for Aquatic Plant Management. Berkshire, UK.
- Daniel E. Terlizzi, Maryland Sea Grant Extension Program, E-mail: [email protected]
- Joseph E. Morris, Iowa State University, E-mail: [email protected]
- John C. Holz, University of Nebraska, E-mail: [email protected]
- Kenneth Langland, University of Florida, E-mail: [email protected]
- Stratford Kay, North Carolina State University, E-mail: [email protected]