Barley straw is an environmentally friendly tool that can reduce algae
growth in ponds and dugouts.
“The exact science is still not understood, however, present research
indicates a benefit to its use with proper timing and application,”
says Stephen Madden, an agricultural water specialist with Alberta
Agriculture.
Allowing barley straw to rot creates processes within ponds and dugouts
that hamper algal growth. Decaying straw does not kill the algae
already present, but it prevents new algae from forming. Also, barley
Read Also
Stock dogs show off herding skills at Ag in Motion
Stock dogs draw a crowd at Ag in Motion. Border collies and other herding breeds are well known for the work they do on the farm.
straw doesn’t hurt fish health or production.
Algae are considered bacteria, capable of fixing nitrogen from the
atmosphere. Combined with phosphorus from runoff, the nitrogen allows
algae to thrive in many prairie lakes, ponds and dugouts. Problems
associated with algae blooms can include plugged water filters and
intakes, discolouration in water clarity, foul odours and oxygen
depletion that kills fish.
Copper sulfate is often used for short-term algae control, but it is
toxic to nontarget organisms that are important food sources for fish,
such as zooplankton and insect larvae. Reapplication of these chemicals
is usually necessary several times a year and the long-term buildup of
copper in the sediments is an environmental and health concern.
Madden said algae control with barley straw varies with the type of
algae.
“Small unicellular species can disappear within six to eight weeks.
Larger filamentous algae can survive for longer periods and adequate
control may not result in the first season if straw is added late.”
Because barley straw is most effective in oxygenated conditions, a
square bale is packed too tight to work. Break the bale into several
loose portions to allow the straw to absorb water and start a thorough
rotting process. Also, the barley straw should be set as close as
possible to the aeration system to ensure water movement through the
straw.
Setup is easy. The material will usually require weights and floats,
because the straw will float until waterlogged.
The goal is to keep the straw in the upper metre of the pond.
The straw becomes heavier than water once it is waterlogged, making
removal of large bales challenging. Make sure all straw is contained in
netting or wire to accommodate complete removal.
“The recommended application rate is 10 grams of barley straw for every
square metre of water surface,” Madden said.
“The barley will require at least one month to start rotting and is
generally active for about six months. To obtain best results, place
the barley in the water in the early spring or in the fall before
freezeup. To keep the algae control cycling, place new barley material
in the dugout one month prior to the removal of the old straw. This
keeps the cycle going with fresh rotting barley always in the dugout.
While other straw types can be used, barley has shown the best results
for algae situations.”
Method for estimating amount of straw required
- Calculate the surface area of the pond or dugout – example 50 m x 30
m = 1,500 square metres.
The recommended application rate of straw is 10 grams per sq. m.
- Multiply the area by the
quantity of straw required – i.e. 1,500 sq. m. x 10 grams per sq. m. =
15,000 g or 15 kg.
- Calculate the number of square bales needed. Divide the total weight
of straw required by the weight of the bales (a small bale is usually
about 20 kg).
- Decide the weight of straw to be placed in each net. (Usually about
three kg per net.)
- Calculate the number of nets to be made – i.e. 15 kg/three kg per net
= five nets.
The nets should be spaced
fairly evenly and be located as close to the aeration circulation as
possible.
