Organic gardeners pride themselves on using only natural and sustainable fertilizers to grow their plants.

I tend to agree -- but only to a point.

To help illustrate the argument for and against chemical fertilizer use I found an interesting quote.

In a story by Dennis T. Avery, a senior fellow at the Hudson Institute in Washington, DC, and director of the Center for Global Food Issues, the UN Food and Agriculture Organization director-general Jacques Diouf was quoted as saying, "You cannot feed six billion people today and nine billion people in 2050 without the judicious use of chemical fertilizers. The FAO has no reason to believe that organic agriculture can substitute for conventional farming systems in ensuring the world's food security."

Of all the facts and position statements that I have read on the issue, few are more telling about where the world is heading with its use of chemical fertilizers.

Reinforcing that position is a quote from the Swedish journal Ambio: "For at least a third of humanity in the world's most populous countries the use of nitrogen fertilizers makes the difference between malnutrition and adequate diet."

Here are some facts about chemical fertilizer production in our world.

Anytime you read a report on worldwide fertilizer use, the consumption amounts are often indicated using metric tonnes or teragrams (Tg). One teragram equals one million metric tonnes.

I thought that was startling enough but then I read this: Approximately 75 per cent of fertilizers and fertilizer technologies used around the world today were developed during the 1950s and 1970s, according to Science Daily.

There have been advances in fertilizer technology since then like slow-released, micro-encapsulated granules and temperature-induced release but overall we are still operating our fertilizer industries on 30-year-old technology.

If the measurement of a teragram doesn't worry you then worldwide fertilizer consumption numbers may give you pause. According to the magazine Pollution Issues, global fertilizer use was 27 million tonnes in 1960; it increased to 141 million metric tonnes in 2000.

So what is the problem with using chemical fertilizers?

I have never been an aggressive user of chemical fertilizer, even when I was responsible for crop production in a greenhouse. Arguably, most people use too much fertilizer, and rely on the "constant feed mentality" as a crutch to grow plants and especially lawn, instead of practising proper crop growing techniques.

The primary problem with chemical fertilizer use is post-application movement (leaching) and secondary interaction (chemical binding) in the environment. One person using a bag of fertilizer on the lawn or garden may seem insignificant, but 32 million Canadians using one bag each leads to problems.

Fertilizer residue has been found in drinking water samples across North America and Europe, in some areas it exceeds the World Health Organization limits of 10 parts per million for nitrates.

Has anyone checked the North Shore water reservoirs for nitrate levels?

Fertilizer runoff into rivers, leaching into groundwater and conversion to gas form (volitazation) is known to contribute to acid rain, decreasing atmospheric visibility, soil and stream acidification, coastal eutrophication (algal bloom and red tide), decreasing biodiversity, human health issues in drinking water and nitrous oxide emissions into the atmosphere.

It's too late to turn away from chemical fertilizer use in worldwide agriculture lest we allow a billion of our brothers and sisters to starve to death, and make no mistake, there simply is not enough manure available to enrich all the farms in the world.

Since agriculture accounts for almost 80 percent of worldwide fertilizer use, what's a gardener to do if he or she wants to go organic and make a genuine difference?

Best fertilizer management practices can help us use less and get more value for the fertilizer we use, which is especially important since more than half of any chemical fertilizer applied is leached away before plants can use it. I suggest the following practices.

Do not fertilize in the spring or fall, when our rainy seasons are most active. Rainfall is a primary cause of leaching of nitrogen and phosphorus into streams and rivers.

Use only slow release, granular fertilizers in the garden. Slow-release fertilizers allow a gradual release of the nutrient according to either soil temperature or moisture, compared to old style fertilizers that are simple granules in a basic form that leach away quickly.

Only apply fertilizer if your plants are unhealthy. Fertilizing the lawn and garden three times a year "just because" is bad for the environment and expensive.

A little goes along way. Never follow the bag recommendations; always use half the bag indicated rate.

Ornamental plants do not require heavy fertilization, unless you want soft tissue growth that is predisposed to pest and disease infestation. Most of all, avoid vanity-based fertilizer use, and we'll all look good.

Todd Major is a journeyman horticulturist, garden designer, writer, lecturer and organic horticulture teacher. For advice contact him at stmajor@haw.ca.