When straw rots, chemicals in the cell walls decompose at different rates. Lignins are very persistent and are likely to remain and be released into the water as the other components decay. If there is plenty of oxygen available in the water, lignins can be oxidized to humic acids and other humic substances. These humic substances occur naturally in many waters and it has been shown that, when sunlight shines onto water which contains dissolved oxygen, in the presence of humic substances, hydrogen peroxide is formed. Low levels of peroxide are known to inhibit the growth of algae and experiments have shown that sustained low concentrations of hydrogen peroxide can have a very similar effect on algae to that of straw.
Peroxides are very reactive molecules and will only last in water for a short time. However, when humic substances are present, peroxides will be continuously generated whenever there is sufficient sunlight. The slow decomposition of the straw ensures that humic substances are always present to catalyze this reaction. There are various factors which affect the performance of straw and which support this hypothesis. It is important to take these factors into account to ensure successful treatment of algal problems with straw.
Type of Straw
Barley straw works more effectively and for longer periods than wheat or other straws and should always be used in preference to other straws. If barley is unavailable, other straws, including wheat, linseed, oil seed rape, lavender stalks and maize can be used as a substitute.
The information in this Guide describes the use of barley straw. If other straws are used, it is likely that the quantities applied and frequency of application may have to be increased.
We have tested a range of barley straw varieties, including some grown organically; all these were active at the same level. Hay and green plant materials should not be used because they can release nutrients which may increase algal growth. Also they rot very rapidly and may cause de-oxygenation of the water.
The anti-algal chemical
The chemical released by the straw does not kill algal cells already present but it prevents the growth of new algal cells. Thus algae which die will not be replaced when the straw is present and so the algal problem is controlled.
Speed of effect
Once the straw has become active, the time taken for control to become effective varies with the type of alga. Small, unicellular species which make the water appear green and turbid, usually disappear within 6-8 weeks of straw application. The larger filamentous algae, often known as blanket weeds, can survive for longer periods and may not be controlled adequately in the first season if the straw is added too late in the growing season when algal growth is dense. It is, therefore, preferable to add the straw very early in the spring before algal growth starts.
Production of the anti-algal activity
Activity is only produced if the straw is rotting under well oxygenated conditions. Usually, there is adequate dissolved oxygen in water to ensure that the chemical is produced by the straw. However, if the straw is applied in large compact masses such as bales, or to very sheltered and isolated areas of water, there will be insufficient water movement through the straw, which will progressively become anaerobic (without oxygen). Under these conditions, only the surface layers of the straw will produce the chemical and so the majority of the straw will have no useful effect.
Absorption and inactivation of the chemical
The chemical is very quickly absorbed by algae and is inactivated by mud. Therefore, in waters which have high algal populations and are turbid with suspended mud, it is necessary to add more straw than in clear waters.
Selective effect on algae
The chemical does not appear to have any effect on higher plants. In our experiments, we have seen that the suppression of dense algal growth has allowed flowering plants (macrophytes) to recolonize waters which were previously dominated by algae. In several shallow lakes where straw was used, algae were replaced by higher plants which suppressed the subsequent growth of algae, so eliminating the need for further straw treatments.
Effects on invertebrate animals and fish
There are no reports of harmful effects on invertebrates or fish except in a few instances where excessive amounts of straw were applied to small ponds and the water became de oxygenated. These excessive doses were at least 100 times the doses recommended in this leaflet. In most instances, invertebrate populations increase substantially around the straw so providing a useful food source for fish. There is anecdotal evidence that, in fish farms and fisheries, straw treatments may be associated with improved gill function and fish health and vigor.
The above information is fact backed by scientific data available on the internet for all to view.
The following information is False information that is given out by some producers of Barley balls and should be disregarded as fiction.
1. preseeded barley....................Fiction ......... The scientific data supports this as fiction.
2. Precharged barley.................Fiction ........ The scientific Data supports this as fiction
3. Organic Barley is more effective or better for your pond .... Fiction.... The scientific Data supports this as fiction, I have even seen preseeded Organic barley, what is organic, but pure and nothing added? and they then claim its Organic and preseeded? So is that right? doesn't seem like it would be. Add to it, it isn't organic.....
4. Why do sellers make such claims?, to sell product and make their products look more enticing to buyers.
5. Netting is material that has at least a 1/8 opening , nylon socks and such do NOT allow proper flow through the bag and you will have a horrid smell coming from the pond as a result of using this type of material. DO NOT use nylons or buy products that someone had packed in nylon socks or pantyhose! The balls also need to float near the top the water is most clear and had less mud or turbidity in the effectiveness of the barley is cut by 75% by sinking the balls in the pond, Sunlight and air play a important part in this process.
You as a buyer, need to realize that if you are dealing with a dishonest seller that will try to deceive you in one way , they will and can be dishonest in other ways as well. Perhaps in the amount of Barley they put in the ball, perhaps in the actual straw itself.
Barley straw can be difficult to find in bulk in some areas of the country, and some sellers have been known to mix straws to make the straw go farther as well as to simply not even use Barley straw at all.
Do you want a working pure product, or a half working get you by product, when the prices are the same or even cheaper for a pure product. That the question you must answer for your self.