611 Making a Weed into a Crop
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#RealisticRegenAg | Have you ever thought that a weed could become a crop? They seem to grow no matter what you do, so why not find a use for it? The plants we use today for crops have been around for centuries and even for millennia. I heard about a new crop being developed from weed and it got me thinking: How do you go about this? This episode is mostly a thought experiment, but it’s a great way to stretch our thinking on what is a crop, what is a weed, and how weeds could be used as, or mimicked, in cover crops.
Welcome to the sixth season of Plants Dig Soil, a podcast about #RealisticRegenAg. I’m your host, Scott Gillespie, and I’m an author and independent agronomist from the Western Canadian Prairies specializing in climate-smart agriculture. I focus on scientifically proven practices that benefit the planet and, just as importantly, farmers' economic sustainability. Be sure to visit my website, www.plantsdigsoil.com, to learn about my book “Practical Regeneration” and for services I that I offer for farmers and agribusiness.
Articles mentioned:
https://www.forbes.com/sites/juergeneckhardt/2024/04/22/biofuels-will-be-a-key-part-of-the-net-zero-solution/?sh=727765985de9
https://link.springer.com/article/10.1007/s13593-019-0592-0
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The weed that is getting developed into a crop is field pennycress. I came across it through an article in Forbes magazine, which I’ll link to in the episode notes. They have renamed it CoverCress to distance itself from its weedy originator. The fit for this new crop is in the sustainable jet fuel space.
The name comes from its marketing. They call it a “cover crop” because it grows in the winter in the temperate areas of the United States, and it doesn’t take land from production of other crops. I say this is borderline. Yes, it covers the soil, but it’s still a cash crop. The seeds are harvested and exported from the land.
Regardless, it’s still fascinating. I searched for information on how it grows, and I was able to find a journal article summarizing the agronomy known up to 2019. I’m sure there’s more known now, but I couldn’t find it online. Perhaps the companies and the agronomists are trying to keep it close? Anyways, here’s what you have to know when you plant a new crop.
First of all, it doesn’t like to be seeded. It is adapted to shattering its seed and spreading it all on the surface. As a weed it doesn’t care if only 10% of it survives, as long as those that do survive make more seeds, it continues on. In the wild it likely gets into the soil through freeze/thaw cycles and from birds and other animals scratching around.
When it’s put in the ground it doesn’t seem to want to grow well. This is likely because the population of seeds are not all programed to germinate at once. As a weed it needs to have some come up early, some at the optimal time, and some later. We expect crops to come up uniformly. Some corn and soybean agronomists consider plants that come up days later than the first ones as weeds. They like to see it all at once. Weeds don’t do this. The population is very vulnerable if they all emerge at once. However, as a crop, the deal is that the farmer is there to protect it as it emerges. The farmer is also there to plant it when the time is right. Over time breeding will improve its uniformity, but for now, it’s a little sporadic coming up.
Next is fertility. In the wild it uses what it can find, makes new seeds, and calls it good. We want it to produce as much as possible. It says, “Well, this is enough for me.” Rate trials have been inconclusive because it seems to do about the same no matter the fertility. Farmer’s that have grown it for a while have vastly different opinions on what works and what doesn’t. We expect that crops grow more with more fertility. However, these crops are expecting us to take care of them. They are expecting that the fertility will last, there will be enough water there to support their massive sizes, and there will be enough season to mature the seeds. In the wild, the goal is to reproduce. More can happen when there is more fertility, but if there isn’t, or the rains stop, they must quickly finish the job.
This crop comes from a known weed. You’d think it would be easy to grow without other weeds taking over. The issue is that it is not commonly grown on its own. It has your crop and other weeds around it. It’s not expecting to be in a monoculture. It has developed resistance to herbicide. But try spraying that on it when you want it to survive! Now it may not die, but it’s not as vigorous as it would be without the chemical. In many cases weeds that are resistant to chemicals have maladaptation’s that make them not so great of competitors. There is a cost to being herbicide tolerant.
Now let’s wrap up with harvest. This reminded me of one of my first “aha” moments at university over 25 years ago. Why do we grow the crops we do? It was because they were selected from plants that didn’t drop their seeds. Think about it. Normally a plant disperses its seeds. It’s unnatural for it to hold onto them tightly. Over time as seeds were collected and some of those were used to plant crops the ones that were kept were the ones that could be harvested by a human.
Pennycress wants to disperse it’s seeds once they are mature. We want CoverCress to hold onto them. It will take decades of breeding to get it to the point where it likes to hold onto them. Most crops took centuries for this to happen.
I hope CoverCress is easy to control in your next crop, because I expect you’ll see a lot of it. If it’s not easy to control, hopefully it gives some benefits.
And here’s a final thought. Rather than trying to fit this new crop into the monoculture paradigm, why not start right from the beginning as an intercrop? It already grows well with many crops. Find ones that match its maturity are easy to separate the seeds from and I’m sure you’ll be further ahead. I was surprised to learn that the current popular intercrop for the prairies, peola (a mixture of peas and canola) has been around for decades. Before there were upright pea varieties and weed control options for canola they were grown together. The peas suppressed the weeds, and the canola gave something for the peas to climb up.
If you want to dive deeper into this, why not check out my new book? As announced previously it is out now and available wherever you buy books, print or for e-readers. Particularly relevant will be chapters 11 & 12 that cover intercropping cash crops and intercropping cover crops.
Thanks for listening. If you’re not already subscribed, please be sure to do so. There are also links in the description for my monthly newsletter delivered through email and LinkedIn. Talk to you again next time.