The Centre for Aquatic Plant
Management (previously the Aquatic Weeds Research Unit) published an information
sheet on the practical application of straw. They have been involved in the
research on straw for about 15 years.
A new method was developed by the Centre
for Aquatic Plant Management for controlling algae. It uses barley straw
in the water and has been tested in a large variety of conditions. They
have documented a high rate of success with no side effects.
What
the Straw Does
Putting barley straw into water, starts
it to rot. A chemical is released which inhibits the growth of algae. They
say it can take about 6-8 weeks for straw to start working at temperatures
below 50°f.
When the water is over 70°f the straw
may start working in 1-2 weeks.
The straw can function for approximately
six months, afterwards gradually decreasing in its
effectiveness.
Calculating
the Amount of Straw
The Center has found that the most important
measurement in calculating the amount of straw is the surface area of the
water. The volume of the water does not seam to have an affect on the efficiency
of the straw. This may be because the majority of algae takes place on
the surface of the water.
For most instances approximately 1 ounce
/ 3ft2 to 3 1/2 ounces/3ft,2 should do the job of controlling algae. After
the algae is under control you can reduce the amount of straw in the water
and use it to prevent a recurring algae bloom.
How to use the Straw In Garden Ponds
Only a couple of ounces of straw are needed.
The straw can be put into a net bag, nylon stocking or tied into a bundle
with string. This can be attached to a stone, or brick, to keep the straw
in place and dropped into the pond. However, as the straw becomes water
logged, it can sink to the bottom, and will not work as well as it does
near the surface.
It is advisable to include some form of
float in the net,
i.e., corks, Styrofoam or small plastic
bottles with tops.
Some pond supply businesses may have small
bales of the barley straw already in netting. Follow the directions supplied
with the straw or just anchor and attach to a float as described
above.
SUMMARY
When algae occur in water from garden
ponds to lakes and rivers, barley straw offers an environmentally acceptable
way of controlling the algae.
Apply it twice each year. (Spring and Fall)
The straw should be in a loose form so
water can pass through it easily.
Straw should not go any deeper than 3
feet. Use floats to keep it up in the water.
If the straw starts to smell then it is
not working and should be removed.
This is caused by too
much straw in too little water.
Copyright IACR-Centre
for Aquatic Plant Management, 1997
