Mark Ross: The environmental benefits of glyphosate

Conventional tillage requires as many as five passes over the land with a plough. Photo / File

Agcarm chief executive Mark Ross argues the case for glyphosate.

COMMENT: Glyphosate, the world's most widely-used weed management tool has extensive economic and environmental benefits for farmers, especially for those involved with New Zealand's grains industry.

The benefits of reducing farming's environmental footprint are immense. Not only do glyphosate-based products successfully control a broad spectrum of weeds, they also help farmers grow crops more sustainably. This is because they allow farmers to adopt 'conservation tillage' - benefiting soil health, reducing carbon emissions and conserving water.

There are countless benefits to the land, the farmer and the environment from adopting a no-till system. First and foremost, by leaving the soil mostly undisturbed and leaving high levels of crop residues behind, soil erosion is almost eliminated.

Utilising crop residues in no-till farming drastically increases water infiltration and therefore retention by the soil, i.e. less evaporation. This conserves water, due to crops requiring less irrigation. It also reduces the runoff of contaminated water – by, for example, fertiliser usage.

Some estimates suggest crop residues provide as much as five centimetres of additional water to crops in late summer. No-till farmed soils have a water penetration rate of 13 centimetres per hour - twice as much as for conventionally tilled land - making no-till farming an excellent option for drought-prone areas of the country.

Because the soil is not frequently agitated, the practice promotes biodiversity in and around the soil. Organisms like mycorrhizal fungi, which make commensal associations with crop roots, and earthworms, increase water retention in the soil. These organisms flourish through no-till farming - benefiting the plant and fungus.

Adopting no-till farming reduces carbon emissions from mechanical equipment as well as labour and fuel costs. Conventional tillage requires as many as five passes over the land with a plough. No-till requires one - to plant the seeds. By running the tractor less, a fuel saving of up to 80 per cent can be realised.

Another way to reduce carbon emissions is by pairing no-till farming with crop covering - planting crops for the express purpose of soil health. This reduces emissions through greater sequestration of carbon dioxide by the soil. Over half of the potential carbon sequestration from farmlands comes from conservation tillage.

Environmental and economic benefits aside - without glyphosate - farmers would need to manually till their land to remove weeds. That would catapult New Zealand farmers back to the agricultural methods of the 1970s and 1980s.

Why would we want to do that, when glyphosate has recorded over forty years of safe use in New Zealand?

There are other herbicides we can use - and other weed control strategies besides those. But, nearly all of them come with greater environmental impacts, especially in our grain industry where it is a cornerstone of no-till agriculture.

It is critical that glyphosate continues as a product of choice for New Zealand. Pushing farmers away from no-till farming and back towards more harmful tools for weed management makes no sense for any self-respecting farmer or environmentalist.

- Mark Ross is chief executive of Agcarm, the industry association for companies which manufacture and distribute crop protection and animal health products.