REAL ESTATE AUCTION

Using Barley Straw to Control Pond Algae

Excessive algae growth is one of the most common problems in ponds. Traditional mechanical and chemical methods of controlling the algae are not always effective or economical. In recent years, the use of barley straw has been found to be an extremely successful method of algae control, when applied correctly.

Barley straw does not kill existing algae, but rather inhibits the growth of new algae. It is not completely understood how this works, although it is thought that the barley straw, in the presence of oxygen and when exposed to sunlight, produces a chemical that inhibits algae growth. Barley straw does NOT reduce the growth of other aquatic plants. In fact, it may allow aquatic plant growth to increase, as the plants have less competition from the algae.

Barley straw is most effective when applied before the appearance of algae in the pond (fall through early spring.) When applied to cold water less than 50 degrees Fahrenheit, it may take six to eight weeks for the straw to begin producing the chemicals that inhibit algae growth. If the straw is applied to warmer water above 70 degrees Fahrenheit, it may become effective in as little as one to two weeks. In any case, the barley straw remains effective for approximately six months after application.

The most common application rate is about two to three bales per surface acre of the pond. The depth of the water is not important. In ponds that have a history of heavy algae growth, two or three times this recommended dose may be required for the initial treatment. However, overdosing the pond may cause fish kill because the straw deoxygenates the water as it decays. This is especially a problem if the pond is overdoes with straw during a prolonged warm spell.

The straw is most effective when it is applied loosely in cages or netting. It is best to anchor the straw packages to the bottom but provide a float to keep the straw near the surface of the pond where sunlight and oxygen are more prevalent. It is best to apply the straw at several locations around the pond and especially near the water source if a stream or spring feeds the pond. In small garden ponds, small nets or nylon stockings can be used to hold the small amounts of straw needed.

Barley straw needs oxygen and sunlight to work properly. Muddy or stagnant water will reduce the effectiveness of the straw. Overdosing as described above could cause fish kills in some ponds.

Finding a local supplier of barley straw can sometimes be difficult. You might consult with private and government agencies that work with local farmers, such as farm supply companies, Soil and Water Conservation Districts and Cornell Cooperative Extension, to find a source of barley straw.

1999

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YEAR BOOK

Effect of successive barley straw treatment on the biomass of filamentous algae in the Royal Canal

Dense growths of filamentous algae pose serious problems for amenity and recreational exploitation in many Irish watercourses. Excessive algal growth impedes boat traffic, obstructs angling, clogs, sluices and lock chambers, in addition to creating unsightly and malodorous masses. The growth of large algal populations can also cause serious diurnal fluctuations in dissolved oxygen levels and result in fish kills. Likewise, the death and decay of a large algal biomass can deoxygenate the water, killing fish and other aquatic fauna. Floating mats of algae can reduce the level of incident light that reaches submerged plants, thereby restricting growth and reducing overall productivity.

Control of filamentous algae in waterways using mechanical methods (cutting, raking, harvesting) has been largely unsuccessful. This is because large numbers of plant fragments remain and vegetation regrowth is rapid. The use of algicides in weed control trials conducted by the Central Fisheries Board on the Royal and Grand Canals provided moderate to good results but, because these herbicides are not selective, they also killed ecologically important submerged plant species.

There is a considerable body of research that demonstrates the antialgal properties of rotted barley straw, properties bestowed without having any discernible adverse impact on higher plants, invertebrate fauna or fish. A primary requirement for the successful use of barley straw is the maintenance of aerobic conditions. Unstable, short-lived algal inhibitors are released during the aerobic decomposition of the straw. These are highly selective against planktonic and filamentous algae and are algistatic rather than algicidal. There is strong evidence that these algal inhibitors are derived from oxidised polyphenolics released from solubilised lignin, although the precise nature or mode of action of the inhibitors remains unknown.

The effects of more than 100 barley straw treatments in the UK and Ireland were assessed, and results reveal that algal control was achieved, to at leasuctivity.

The effects of more than 100 barley straw treatments in the UK and Ireland were assessed, and results reveal that algal control was achieved, to at least some extent, in all types of water body, but was better in smaller watercourses (<5ha).

An algae infested section of the Royal Canal near Abbeyshrule.

Mattress of barley straw being placed in the Royal Canal at Mullingar.

Detailed trials conducted on an algal infested section of the Royal Canal between 1990 and 1993 demonstrated the effectiveness of barley straw in inhibiting nuisance algal growth. Mattresses of loosened straw, retained in garden netting, were anchored along the banks in the trial section. These were spaced at 50m intervals and alternated from bank to bank. A quantity of straw to provide a dose of 10g per cubic metre was applied. The straw was replaced at roughly six month intervals. A contiguous, untreated control section was monitored for comparative purposes.

Algal growth in the section broadly followed a cyclical pattern, with peak biomass between July and September and low production in February and March. In the treated section, however, algal biomass decreased from the time the straw was first introduced. Thereafter, as long as rotted straw was present, no filamentous algae were recorded. The absence of algae in this section between August 1991 and Spring/Summer 1993 permitted the recolonisation of higher plants, which are commonly less troublesome and more ecologically useful in fishery waters than algae. Further trials have produced similar results, and barley straw is now routinely used for algal control in many aquatic situations.

Controlling Pond Algae with Barley Straw

Algae are microscopic, free-floating plants which comprise a critical component of a lake's food web. They are fed upon by tiny animals called zooplankton which are an important food source for fish. Algae color the water green or brown, and uncontrolled growth can lead to nuisance surface scums, poor water clarity, noxious odors and an overall reduction in the lake's recreational value. Excessive levels or "blooms" of algae occur when nutrients, especially phosphorus, are abundant. After taking steps to reduce the amount of phosphorus entering a lake, it may be desirable to control the algae growth directly. Typically this is accomplished by treating the lake with copper-containing compounds such as Cutrine Plusr or copper sulfate. These treatments are effective short-term controls of algae, but they are also toxic to nontarget organisms that are important food sources for fish such as zooplankton and insect larvae. Re-application of these chemicals is usually necessary several times each year and the long-term buildup of copper in the lake sediments is an environmental and health concern.

The Centre for Aquatic Plant Management (CAPM) in the

United Kingdom

is promoting a method of controlling algae that involves the application of barley straw to lakes. As the straw decomposes in the lake, it releases a chemical which inhibits algal growth. This method may be a good alternative to using copper-containing compounds since it is not known to have toxic effects on rooted aquatic plants, zooplankton, insect larvae or fish. It appears to be a cost-effective and environmentally acceptable way to control algae in ponds and lakes.

When to Apply the Straw

The decomposition process is temperature dependent and occurs faster in warmer water. When the water temperature is below 50^oF, it takes approximately six to eight weeks for the decomposing straw to produce enough of the growth inhibiting chemical to effectively control algae. However, it only takes one to two weeks when the water temperature is above 68^oF. Once the straw begins to produce sufficient amounts of the chemical, it is likely to control algae for four to six months. Therefore, straw should be applied in mid-late April in order to control summer algal growth in Nebraska ponds and lakes.

Amount of Straw to Apply

The amount of straw required to control algal growth depends on the surface area of the lake. Lakes with a history of algae problems should be treated at a rate of 225 pounds of barley straw per surface acre. This rate is equivalent to about 0.8 ounces of straw per 10 square feet of surface area. Lower doses can be tried, but should not fall below 90 pounds of straw per acre or 0.3 ounces per 10 square feet.

The effectiveness of the straw is reduced by sediments suspended in the water (i.e. "muddy" water). Therefore, a higher dose may be required in "muddy" lakes or lakes with extremely severe algae problems. In these types of lakes, apply 450 pounds per acre (1.7 oz per 10 square feet), but do not exceed 900 pounds per acre (3.3 oz per 10 square feet). The decomposition of the straw requires oxygen, and applying excessive amounts (greater than 900 lbs per acre) of straw could reduce the oxygen content of the water to levels that stress or kill fish.

How to Apply the Straw

Where to Apply the Straw

In order to improve the distribution of the growth inhibiting chemical, CAPM recommends placing several small quantities of straw around a pond. Place each net of straw roughly equidistant from other nearby nets and the shore. The placement of the nets does not need to be exact and practical considerations such as corridors for boating and angling may influence the location of the nets. In small ponds where only one net of straw is required, place the net of straw in the center of the water body.