How Does Barley Straw Work?
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Open To Question
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Over the past decade, the use of barley straw to control algae in open ponds, lakes and waterways has gained a lot of comment. The use, which took hold in Great Britain originally, has not yet fully proven to work, however, and the mechanism that comes into play is a matter for many theories but no proofs to date. That said the results have been sufficiently promising to encourage further examination and experimentation.
If It Works, How Does It Work?
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The simple answer is that no one seems to be sure. There are a number of theories, none proven, but no firm answers. Some think perhaps the hydrogen peroxide produced by bacteria as the barley hay decomposes discourages algal bloom: hydrogen peroxide is one of the chemicals often used in aquaculture to kill off algae. Others think the bacteria or the straw itself release enzymes into the water that act to reduce algae populations. Some think the carbon left after straw has decomposed alters the chemical balance of ponds and lakes in a way hostile to algae growth. In the end, though, the fact is no one is yet completely certain barley straw works very consistently, much less having a clue why it works if it does. The only thing that can be said with certainty is that there are ponds and lakes in which barley straw has been used which no longer are suffering algal bloom.
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What's The Catch?
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If barley straw does what it's supposed to do, there is no real catch--but you must use the straw in the right amounts, the right form and format, and at the right time. Using the straw appropriately may very well eliminate a nasty algae problem. Using it inappropriately will almost certainly cause plenty of other problems without putting a dent in the algae.
So here are the basic rules: you must use barley straw, not some other grass straw. You must use dry straw, not hay or fresh clippings, which only add nitrogen to the water and actually encourage algal growth. The straw must be well oxygenated: that means you have to pack it loosely, with plenty of water flow in and out of the net bag that holds the straw. You must keep the straw near the surface of the water with floats on the netting. You must use the right weight for the volume of water you need to treat. Formulas for weight-to-water-volume can be found online at a number of sites, including some state agricultural sites. Finally, you must put the straw into the water at the right time. Barley straw appears to function as a preventive rather than as a cure for an existing algal bloom: think of it as inoculating your pond against algae, rather than curing it from a bad case of algae. Put in several months prior to peak algae bloom times, barley straw seems to prevent algae growth. Put in during the middle of an algae bloom, it appears to do nothing useful at all.
Remember that the technique, while promising, is not yet proven and is hotly contested by some parties. Proceed with optimism, but not with certainty.
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