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Your home and garden fertilisers will be changing. Legislation in Western Australia has come into effect which limits the amount of phosphorous and nitrogen used in garden and lawn fertilisers, with other Australian states such as Queensland set to follow suit.

With the aim of protecting our waterways, the new regulations will drastically reduce the amount of phosphorous used in fertilisers and therefore the amount that is leaching into the environment from gardens and yards.

The overuse of nitrogen fertilisers can lead to the contamination of groundwater and surface water, causing water to be unfit to drink and algal blooms. The overuse of phosphorous fertilisers (which the new legislation seeks to address), can lead to soil contamination with impurities like cadmium* and contamination of surface waters after being washed off or out of the soil, again causing algal blooms.

As an overall, the new amounts of phosphorous in domestic fertilisers will be:

  1. Lawn Fertilisers – maximum content of 1% – previously it was 3.5%.
  2. Garden Fertilisers – maximum content of 2%.
  3. In addition all fertilisers with more than 0.5% phosphorous will need to contain a nitrogen:phosphorous ratio of between 5:1 and 20:1.

This new legislation came into effect 1st January 2013 however, you may still find the higher concentrations available where an extension has been sought by the manufacturers in order to deplete their current stock.

All new fertilisers produced by law since this date, will need to exhibit a label to acknowledge the new phosphorous contents.

Currently Sir Walter Fertilisers contains a fairly low amount of 1.8% phosphorous however, it to will be changing production to 0.09% phosphorous.

While the new fertiliser legislation aims for a reduction of the environmental impacts of phosphorous and residential fertilisers use, the additional benefit is an economic one and a benefit for lawn lovers. Much of the fertiliser applied to lawns and gardens is never actually used. More awareness of the chemical compounds within the available fertilisers will hopefully lead to people firstly conducting a pH soil test and then applying the exact quantity that your lawn requires. Applying too much fertiliser and too often is not only a problem for the environment, but is a waste of your hard earned money. If you apply fertiliser according to the actual need of the lawn you stand to save; your local waterways and your wallet.

*Cadmium and its compounds are generally considered to be carcinogenic with long term and high level exposure and can irritate organs such as the lungs and intestines if inhaled or ingested. Cadmium bio-accumulates, concentrating in the body without being eliminated as other toxins are. People may be exposed by polluted air and water and once an area is polluted it is very difficult to remove.

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