Will Weeds Halt Carbon Farming in its Tracks?

Nandan Kalle, Greenfield Robotics

​A few weeks ago I wrote a little about the links between carbon farming, weeds, and agrichemicials.  This time we dive deeper to explain the links and challenges.

Carbon farming, or regenerative farming, is a system of agriculture that invests in soil health, bringing a number of benefits to farms, the food system and the environment.  Key benefits of regenerative farming include:

• reduced reliance upon chemical fertilizers
• improved farm profitability
• perhaps most importantly, carbon sequestration which fights global warming (World Bank, 2012).

One of the pillars of regenerative farming is no-till: rather than tilling the soil to bury weeds before planting, regenerative farmers leave the soil undisturbed and use other methods to control weeds.  About half of U.S. farmland is now no-till or reduced-till (USDA 2017 Census of Agriculture); these farmers see numerous benefits including lower operational costs, improved yields, and reduced need for chemical fertilizers.
However, this shift has been largely enabled by the use of chemical herbicides (in lieu of tilling) to control weeds.  These chemicals bring their own problems, and the issues are becoming increasingly urgent. Without effective alternatives for weed control, the transition to regenerative farming potentially slows or halts- jeopardizing a powerful tool for fighting climate change.

Roundup faces multibillion-dollar legal challenges

Roundup- Once a Star Performer Against Weeds, Now a Problem Child
Glyphosate (marked by Monsanto as Roundup) is perhaps the most widely-used chemical in agriculture, and largely enabled the transition to no-till over the past several decades.  Paired with “Roundup-ready” seeds - crops genetically engineered to be resistant to Roundup - the product is simple to use; it kills everything except for the GMO crops. However glyphosate is increasingly problematic.
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The popular press widely reported the $2B court verdict against Bayer (Monsanto’s parent company) for cancer deaths resulting from exposure to glyphosate (New York Times, May 2019).  While the initial verdicts are under appeal, there is a backlog of thousands of cases which could pose major financial liability to the company and the viability of the product.  Other research identifies potential links between glyphosate and gluten intolerance (Samsel and Seneff, 2013), while an increasing number of independent tests suggest glyphosate is widely present in our food (Environmental Working Group, 2019).

Aside from health and safety concerns, another practical risk has emerged: Roundup-resistant weeds.  Weed strains evolve over time, and two particularly invasive species- palmer amaranth (“pigweed”) and marestail- are largely resistant to glyphosate (Purdue Extension report).  This has caused farmers to turn to a “cocktail” of chemicals, including glyphosate and dicamba, an older herbicide.  Earlier this month, the Wall Street Journal wrote extensively about the agrichemical giants struggling to keep up with weeds.

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Farms are forced to rely on additional chemicals like dicamba, which bring their own set of issues

Dicamba - Older Herbicide Brings More Issues
The herbicide Dicamba, while somewhat effective against pigweed and marestail, is even more problematic.  Aside from increasing farmers’ herbicide costs, dicamba has complex application protocols- users must be certified in order to spray it (Environmental Protection Agency).  
​Despite these protocols, dicamba easily becomes airborne, drifting into neighboring areas - destroying other crops or tainting the environment.  In response, several states have imposed restrictions on dicamba usage. Arkansas, Illinois and Indiana have each announced tightening of dicamba restrictions for 2020 (Associated Press, Progressive Farmer, Agweb); as restrictions tighten, farmers are constrained in how they may  use the herbicide to fight weeds- putting their crops increasingly at risk.

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Meanwhile Weeds Keep Getting Tougher
And nature continues to innovate- with signs of dicamba-resistant weeds emerging.  In August, Progressive Farmer reported a number of instances of palmer amaranth demonstrating resistance to dicamba; anecdotal reports suggest the patterns are similar to when the weeds developed resistance to glyphosate.  If dicamba-resistant weeds spread, then farmers may have to use more herbicides, at increasing cost, and introducing more chemicals into the environment.

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Regenerative Farmers Need Better Ways to Control Weeds
Regenerative agriculture holds great promise for mitigating climate change, but in order for regenerative farming to scale, farmers need a “third way” to control weeds - aside from tilling and chemicals.  While manual weed removal may be viable on small CSA’s/specialty farms, it does not scale to broadacre farms - corn, soy, cotton, wheat - that represent 90% of the cropland in the U.S. The current approach - chemical herbicides - is not very palatable to those concerned about the environment, and increasingly ineffective to boot.
Greenfield Robotics has developed a solution to this problem for broadacre farmers, and is preparing for trials in 2020.  More information to come- stay tuned.