Phosphorus is an essential element in plant growth. But, the phosphorus necessary for plant growth is miniscule compared to the amounts typically spread while fertilizing. When too much phosphorus is added to lawns, gardens, and other agricultural areas, precipitation washes excess into lakes, rivers, and ponds.

This excess phosphorus in Wisconsin’s waterways leads to increased phytoplankton growth, more commonly known as algae blooms. These blooms are the easily recognizable green, thick and foul-smelling slicks on top of the waterways. These algae blooms grow quickly, then die and decay, consuming large amounts of oxygen out of the water, frequently killing many fish in the process.

Another, and potentially dangerous, situation can occur when phosphorus washes into waterways. Extremely high levels of phosphorus can produce colonial cyanobacteria, known as blue-green algae. Blue-green algae can release extremely deadly liver and nerve toxins that, even in small doses, can injure or kill humans and pets.

Therefore, in April 2009, Governor Jim Doyle signed the Wisconsin Zero-Phosphorus Fertilizer Law (Wisconsin Statute 94.643). This law, which took effect as of 1 April 2010, restricts the use, sale and display of lawn and turf fertilizer which contains phosphorus or available phosphate. Use of this type of fertilizer is prohibited on lawns and turf in Wisconsin, except under certain exemptions.

The Phosphorus Fertilizer Ban will affect homeowners, renters, and other who do lawn care, along with lawn care professionals, municipalities and local governments, and retailers who sell fertilizer in the state.

Use of fertilizer containing phosphorus or available phosphate for non-turf use is permissible. Such fertilizer may be used for agricultural production or home garden use.

The specifics of the law are as follows:

Restriction on use
– Besides the following exemptions, no person may intentionally apply to turf fertilizer that is labeled as containing phosphorus or available phosphate.
– This prohibition does not apply to a person applying fertilizer to establish a newly seeded and/or sodded lawn during the first growing season of establishment.
– This prohibition does not apply to an area deficient in phosphorus, as shown by a soil test, performed by a laboratory, no more than 36 months prior to application of fertilizer.
– No person may apply fertilizer, animal or vegetable manure, or composted sewage sludge to lawns or turf while the ground is frozen.
– Ground is considered unfrozen when a person can dig down six to eight inches.
– No person may intentionally apply lawn or turf fertilizer, animal or vegetable manure, or composted sewage sludge to hard surface areas like sidewalks, driveways, concrete, or parking lots. If accidental application occurs, it must be removed immediately.
– Also prohibited is the removal of fertilizer into storm drains. Accidentally applied fertilizer should be swept up and/or hosed into grass.

Restriction on Sale
– Sale of fertilizer labeled as containing phosphorus or available phosphate is prohibited if the purchaser intends to use the fertilizer for reasons besides the following:
– Establishment of new lawn or turf using seed or sod, during the first growing season of establishment.
– For application in a phosphorus-deficient area, as shown by a soil test, performed by a laboratory, no more than 36 months prior to application of fertilizer.
– For application on pasture, land used to for the growth and production of sod, or any other land utilized for agricultural production.

Restriction on Display
– No retailer that sells fertilizer may display fertilizer labeled as containing phosphorus or available phosphate. A retailer may post a sign informing customers fertilizer containing phosphorus or available phosphate is available upon request.

Penalties under Statute 94.643
– A first-time offender cannot be penalized more than $50.
– Subsequent offenders will be penalized anywhere from $200 up to $500 for second and additional infractions.

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