The Role of Glyphosate in Regenerative Agriculture

One way commercial farms use glyphosate is for terminating pasture fields, allowing crops to be grown on grazing lands without heavy tillage. This is not how glyphosate ends up in food.

The story of how glyphosate used on farms ends up in food goes back to the 1990’s, when ‘Roundup Ready’ corn, soybeans, and canola were introduced. Genetic modification (GM) allowed these crops to be sprayed with the herbicide Roundup to kill weeds mid-season.

Starting in the mid-2010’s, some farmers started spraying non-GM cereal and legume crops with glyphosate (the active ingredient in Roundup, now available generically) prior to harvest. This too helps control weeds and kills the crop at the same time, because wheat, barley, oats, peas, lentils, chickpeas and beans have not been genetically modified to survive an application of glyphosate.

In grain-growing regions where it is not common to spray the standing crop prior to harvest (i.e. desiccation), cereal and legume fields swathed and laid in furrows to ripen and dry down. Consumer backlash against pesticide residues in oats in recent years caused millers to ban pre-harvest glyphosate, forcing farmers to return to swathing in order to market that crop.

Swathing is a more complicated process for ripening a crop compared to spraying it, and harvest timing is more variable. If the weather turns cool and wet, grain in swaths can end up downgraded due to sprouting, mildew and discoloration.

Macroeconomic Drivers of Pre-Harvest Desiccation

In recent decades, commercial grain farms have been pushed to expand to achieve economies of scale, reducing unit costs for big-ticket items like machinery by spreading them across a larger and larger land base. It’s a cycle that feeds on itself, as farming more land requires more and bigger equipment, squeezing margins and in turn requiring more farmland to justify rising machinery costs.

The risk of downgrading due to unpredictable harvest timing amplifies on a farm as it expands. Controlling ripening through desiccation simplifies the operation allowing more acres to be combined in less time, and on time to meet market deadlines.

Pre-harvest desiccation also results in more uniform kernel sizing and less dockage (weed seeds, broken kernels, chaff, etc.), which is appealing to the elevators that first buy grain from farmers. There are products other than glyphosate registered for the express purpose of desiccating field crops, but they are more expensive and from the farmer’s perspective they do the same job.

As Canada’s Keep it Clean explains, off-label pesticide applications are illegal and can lead to unacceptable residues in the harvested grain. Still, lots of farmers do it anyway, have been for years, and consider there to be not a thing wrong with it.

Glyphosate in Grazing Systems

Farms that integrate a managed grazing period into their field rotation benefit from the nutrient-cycling and pest resistance that biodiversity naturally provides to soils and crops. The dense mat of a multi-species pasture can choke out tough patches of weeds, while manure from livestock attracts beneficial insects that help break down plant material into soil organic matter.

Here’s how it works: after a few years of grazing a plot of land, the time comes to grow a crop. To terminate the pasture and prepare the seedbed for planting, the farmer faces two choices:

1. Till it deeply and repeatedly, or

2. Spray it with a non-selective herbicide like glyphosate.

For conventional and certified organic farms alike, the crux of this decision is how best to preserve biological actors like butterflies, bees, earthworms, beetles and mycorrhizal fungi, in the process of switching from a forage to a field crop. These organisms cycle nutrients between the air, plants, roots, and soil, feeding the crop more profitably, and without the associated greenhouse gas (GHG) emissions of commercial fertilizer.

There is no ‘right way’ to terminate a forage field - nor is there any judgement between different types of farmers who are working to regenerate their soils. A no-till farmer finds the idea of breaking up pasture mechanically just as disturbing as an organic farmer finds the idea of applying chemicals. With one common goal, each farmer discerns the best management of their soils, amidst the specific context of their operation.

Summary

The truth is, not all farmers are working to regenerate their soils. For a host of reasons, large-acre commercial grain producers can fixate instead on seeding and harvesting as efficiently as possible, maximizing yields and maintaining weed-free fields.

Glyphosate ends up in food when these types of farmers aren’t paying attention to the potential for land management decisions to contaminate food supply chains. They seem to forget that every truckload of grain eventually ends up on someone else’s dinner plate.

Based on topography and other natural variations, fields rarely ripen evenly, leaving some spots still green and growing while others are ready to harvest and take to market. When glyphosate is sprayed on plants that are still growing, it is taken up into the seed as the heads are filling.

Chemical residues can also remain on the surface of fully ripe grain that is sprayed. This would seem to be the cause of glyphosate in harvesting and transportation equipment, grain elevator bins and augers, trucks, railcars, and ocean shipping vessels.

Using glyphosate to terminate pasture before planting a field crop offers no such obvious link to it ending up in food. In grazing rotations, it is applied to plants that are not harvested for human consumption, and in lieu of otherwise heavy soil disturbance.