Profile picture
Dr Sarah Taber @SarahTaber_bww
, 25 tweets, 4 min read Read on Twitter
This question is for crop scientists what "can you look at this rash??" is for dermatologists

except at least some rashes really are bad news and this one is entirely spin
So here's the deal.

Plants basically grow as big as they can, given the nutrients available.

nutrient*s*
Plants need different amounts of dft nutrients. Say a plant needs 10g of nitrogen (N) & 0.1g of iron (Fe) to make 1kg of plant.

So if you give a plant a manure mix with 10g of N and 1g of Fe, it has *just enough* N and *way more Fe than it could ever possibly need.*
Back in the day when we didn't have a great picture of plants worked, we just threw on all the fertilizer we could & hoped for the best. That often wound up giving plants way more than they needed of trace nutrients like iron, zinc, cobalt, manganese, etc.
So sometimes the plant tissue had unnecessarily high levels of micronutrients.

Keep in mind these are *micronutrients,* e.g. by definition they're things that both humans & plants only need a very small amount of.
At the present time, we're a lot better at knowing what plants actually need & just giving them that. Instead of throwing the kitchen sink at them like we used to.

That's not really a bad thing. Throwing more nutrients on a field than the plants can use tends to cause pollution.
So now if a plant needs, for ex, 10g of N and 0.01g of Fe, we give it something pretty close to that ratio of nutrients.

So now plants just have about the same micronutrient levels in their tissue that they actually *need.* Not inflated levels.
The article makes it sound like the plants are somehow starving -> we're gonna starve.

That's not how plants work.

If plants are legitimately not getting enough of any one of the several nutrients they need, THEY WON'T GROW
If a plant's healthy enough to grow & produce an edible crop, by definition, it has "enough" nutrients. An actual starving plant won't make anything for a farmer to sell.
Sooooo basically the news here is "healthy plants that weren't overfertilized have slightly lower trace nutrient levels than plants that were"

which is really not news. that's literally just crop nutrition 101.
Folks who are getting all their nutrients from plants generally eat at least some concentrated forms of plants, especially concentrated plant proteins: tempeh, seitan, nut milks & butters, etc.

These also concentrate the micronutrients.
Again: we're talking about *micronutrients* here. For iron, the micronutrient humans need the most of, we need 10-20 milligrams per day.
The "reductions" (actually, "returns to appropriate levels") in plant micronutrients we're looking at are not very significant, compared to how much a balanced human diet of any kind would provide.
Also, the experiments on CO2 effects on plant nutrition are generally done with keeping nutrient levels exactly the same & juicing some plants up with CO2.

Except on a real farm, if plants are growing faster bc of more CO2, we ... just deal w it by giving them more food.
That research is done under controlled growth chamber conditions *with carefully limited nutrients, to figure out some basics of plant physiology.*

In real life, you know, you fertilize plants to keep up with how much they need. So you don't get those nutrient reductions IRL.
As far as the alarming quotes from scientists, sometimes folks doing basic science can be a little disconnected from how crops are actually grown in the field.

My entire job is "translating research results into actionable on-farm info." Uhhh... this job exists for a reason.
Something that's a way bigger threat to vegan micronutrient intake than normalized plant micronutrient levels:

Raw leafy greens.
Most of the iron, calcium, etc in leafy greens are bound up w oxalic acid. OA forms crystals that deter caterpillars/keeps them from growing by locking up nutrients. They give leafy greens that slightly chalky mouthfeel.

Cooking destroys oxalic acid & releases the nutrients.
Leafy greens have a lot of micronutrients*. But eating them raw actually reduces what we can absorb to about 1/8 or 1/9 of what's actually in the plant. We just poop out the rest, still tied up with oxalic acid.

*for plants
To review: eating leafy greens raw cuts the nutrients we can get from them by 75-85%.

Meanwhile, the nutrient reduction we get from this panicky-sounding soil nutrient issue maxes out at 8%. And is completely eliminated by managing fertility to keep up w plant needs.
I mean... this is peak food marketing industrial complex. The basics of plant nutrition mean spinach today might be a few ppm lower than the overfertilized ditchweed of the past, and that's spun into some kind of existential doom scenario.
Meanwhile if we eat raw leafy greens we wind up pooping out 80-90% of the nutrients actually in them, but they're sold as the ultimate in health food.

This is a scenario known in the crop science as "what the actual frick is wrong w the food press."
"Crops are less nutritious than they used to" is a 100% made-up problem.

It's disappointing that the food press keeps writing about it.

But a lot of food writers just don't know any better, & making readers nervous is good for sales. So they keep writing about it.
tl;d sometimes clickbait has high production values. But don't worry mate, don't lose sleep over this one.
Missing some Tweet in this thread?
You can try to force a refresh.

Like this thread? Get email updates or save it to PDF!

Subscribe to Dr Sarah Taber
Profile picture

Get real-time email alerts when new unrolls are available from this author!

This content may be removed anytime!

Twitter may remove this content at anytime, convert it as a PDF, save and print for later use!

Try unrolling a thread yourself!

how to unroll video

1) Follow Thread Reader App on Twitter so you can easily mention us!

2) Go to a Twitter thread (series of Tweets by the same owner) and mention us with a keyword "unroll" @threadreaderapp unroll

You can practice here first or read more on our help page!

Did Thread Reader help you today?

Support us! We are indie developers!


This site is made by just three indie developers on a laptop doing marketing, support and development! Read more about the story.

Become a Premium Member and get exclusive features!

Premium member ($3.00/month or $30.00/year)

Too expensive? Make a small donation by buying us coffee ($5) or help with server cost ($10)

Donate via Paypal Become our Patreon

Thank you for your support!