Choose to know how to grow
When chemical fertilizers containing phosphorus are applied to lawns to maintain a thick growth of rich green grass, they may contain a greater amount of phosphorus than the plants can use. With snow melt and rain, this excess phosphorus can wash into ditches and storm drains that lead to rivers and lakes. Fertilizers applied to lake and riverfront properties are also easily washed into waterways.
Once in the waterways, phosphorus in the runoff can promote excessive growth of algae and water plants. These, in turn, can deplete the water's oxygen supply, killing off fish and other organisms..
Manitoba restricts phosphorus on lawns
Manitoba is the first province in Canada to pass a regulation restricting the use of fertilizers containing phosphorus on lawns. By 2009, with a few exceptions, property owners fertilizing their lawns will be restricted to products containing no more than one per cent of phosphorus (as P2O5). As most of our soils are already rich in phosphorus, for the majority of Manitobans this restriction will not affect the ability to maintain a healthy lawn.
Fertilizers containing phosphorus will still be permitted in the following situations:
- a soil test indicates a need for phosphorus
- on newly established lawns
- on flower and vegetable gardens
- on agricultural crops
No fertilizers - not even low and zero phosphorus products - will be permitted
along waterways such as rivers, lakes, streams, wetlands and retention ponds. In
these areas, defined setbacks must be observed:
- at least 30 metres along vulnerable lakes, such as Lake Winnipeg and Killarney Lake
- at least 15 metres along all other lakes and vulnerable rivers, such as the Red and Assiniboine rivers
- at least 3 metres along all other waterways
More information is available at:
http://www.gov.mb.ca/waterstewardship/wqmz/index.html
Look for a zero in the middle
When shopping for your lawn fertilizer, check the middle number. The three numbers on a fertilizer bag represent its percentage of nitrogen, phosphorus (expressed as P2O5) and potassium (expressed as K20) content, in that order. When choosing a lawn fertilizer, look for a product labelled with zero as the middle number. Even with zero phosphorus products, it is important to read package labels and carefully follow instructions to avoid over-fertilizing.
Currently, retailers carry fertilizer products with phosphorus levels up to 20 per cent. However, low phosphorus and zero phosphorus fertilizers are currently available. Manitoba Water Stewardship is discussing this issue with industry associations in an effort to make the transition easier for retailers and consumers alike. In Minnesota, where similar regulations were successfully implemented in 2005, home and garden centres were quick to adapt, offering a range of compliant products and accurate information.
Consider the alternatives
There are effective alternatives to chemicals that homeowners can choose for their lawns and gardens:
- Spreading your mulched grass clippings is a no-cost option to boost soil fertility while also increasing moisture and shade for your lawn.
- Composting your lawn clippings, plant materials from your garden, along with your kitchen organic wastes will yield a rich dressing to feed your lawn, with the added benefit of reducing waste and greenhouse gases.
Homeowners may also wish to consider alternatives to all or a portion of their traditional lawns, such as natural habitat projects or rock gardens. Gardening with native plants will reduce the need for fertilizers, pesticides and water.
