Making pesticides safe
OPINION: A culture of trepidation about consuming foods which have been exposed to pesticides is misleading and has sparked much confusion of late.
Read: US case heats up Roundup debate.
The benefits of reducing farming’s environmental footprint are immense. Not only do glyphosate-based products successfully kill a broad spectrum of weeds, they also help farmers grow crops more sustainably by enabling farmers to practise ‘conservation tillage’ — benefiting soil health, reducing carbon emissions and conserving water.
No-till farming brings countless benefits to the land, the farmer and the environment. Firstly, by leaving the soil mostly undisturbed and leaving high levels of crop residues behind, soil erosion is almost eliminated.
Using crop residues in no-till farming greatly increases water infiltration and therefore retention by the soil, i.e. less evaporation. This conserves water, due to crops requiring less irrigation, and it reduces the runoff of contaminated water by, for example, fertiliser usage.
Some estimates suggest crop residues provide as much as 5cm of additional water to crops in late summer. No-till farmed soils have a water penetration rate of 13cm/hour -- twice as much as for conventionally tilled land -- making no-till farming an excellent option for drought-prone regions.
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.
No-till farming reduces carbon emissions from mechanical equipment and saves labour and fuel costs. Conventional tillage requires as many as five passes over land with a plough. No-till requires one — to plant the seeds. Running the tractor less can cut fuel usage by 80%.
Another way to reduce carbon emissions is by pairing no-till farming with crop covering -- planting crops specifically for soil health. This reduces emissions by sequestering more carbon dioxide by the soil. At least 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 NZ farmers back to the methods of the 1970s and 1980s.
Why would we want to do that when glyphosate has recorded at least 40 years of safe use in NZ?
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 NZ. Pushing farmers away from no-till farming and back towards more harmful tools for killing weeds makes no sense for any self-respecting farmer or environmentalist.
• Mark Ross is chief executive of Agcarm, the industry association for companies making and distributing crop protection and animal health products.
