Can We Feed Billions of Ourselves Without Wrecking the Planet?
We are now producing more food more efficiently than ever, and there is plenty to go around for a human population of 7 billion. But it is coming at a drastic cost in environmental degradation, and the bounty is not reaching many people.
Sustainable Food Production, a new Earth Institute primer from Columbia University Press, explores how modern agriculture can be made more environmentally benign, and economically just. With population going to maybe 10 billion within 30 years, the time to start is now, the authors say.
The lead author is ecologist Shahid Naeem, director of the Earth Institute for Environmental Sustainability. He coauthored the book with former Columbia colleagues Suzanne Lipton and Tiff van Huysen.
This is an interesting interview with the author. Do you agree (or disagree) with his conclusions?
[Also Covered By]: Phys.org
(Score: 0) by Anonymous Coward on Friday January 14 2022, @09:05PM (19 children)
"No legume has to keep up."
If they want to be a commercially viable alternative to bulk urea, then yes, they have to keep up. By definition. Otherwise, urea wins. And by the way, the fact that you need to grow your legume all season and then turn it back into the soil just to get it all in there for the next year's corn planting means that you can't even use it for fodder - you need the whole plant to get into the soil for available nitrogen or you're back at square 1, minus the other nutrients sucked up by your clover, pea, or whatever.
"They grow and fix nitrogen all season."
No, they don't. They have growing cycles same as any other plants. A quick search yielded https://cropwatch.unl.edu/2016/nitrogen-fixation-oversold-legume-cover-crops [unl.edu] which points out that "It is important to note it can take up to six weeks after planting before N fixation begins." not to mention the other caveats in that article about growing conditions, scavenging of available N in the soil and so on.
"My take is you will be surprised how much green manure does now."
Maybe I will be surprised. I mean, I just studied and use this knowledge in the real world, what do I know?
(Score: 1) by khallow on Saturday January 15 2022, @05:38AM (18 children)
So right there we have roughly half as much nitrogen provided by nitrogen fixing plants as we do by nitrogen chemical fertilizer worldwide. And for some soybean crops, 30% of its nitrogen needs (possibly less if those "elite cultivars" can deliver) are met with fertilizer or animal manure.
(Score: 0) by Anonymous Coward on Saturday January 15 2022, @04:15PM (17 children)
First: as you say yourself, half. That's a log of pig and chicken shit to make up the gap.
Second: you do know that they actually fertilise soy fields with nitrogen, right? because until those nodules start their fixing magic, soy seedlings are nitrogen-hungry little bastards.
Third: The soybean doesn't actually leave a whole lot of nitrogen in the soil unless you don't harvest, and turn it back in. Why? Because we like to eat the nitrogen-rich seeds, thereby removing that nitrogen from the cycle. The fact that the soybean happened to fix the nitrogen from the atmosphere is irrelevant to the broader nitrogen cycle if the first thing that we do is to yoink it from that exact same cycle.
Everything that you typed there can be utterly unimpeachably true, and still not help in our vision of sustainably feeding the world.
(Score: 1) by khallow on Sunday January 16 2022, @02:07AM (16 children)
I sense those goalposts amoving because the other big number here is three. That is, increase that amount supplied by green manure by a mere factor of three, and you've replaced the nitrogen supplied by fertilizer.
The usual approach is to plow in the plants (usually not soybeans) before they seed. I was just pointing out that these soybeans were so self-contained that they supplied most of their own nitrogen through to harvest. That's pretty good.
(Score: 0) by Anonymous Coward on Monday January 17 2022, @02:12AM (15 children)
"That is, increase that amount supplied by green manure by a mere factor of three, and you've replaced the nitrogen supplied by fertilizer."
That means that you're not paying attention.
Let's take this from the top:
Today, I can ride up to a field with sacks of NPK plus various other amendments depending on things such as soil acidity, knife them in (or otherwise incorporate them), in quantities that no legume would possibly provide in a whole season by itself, and then be ready for a full season of growing *insert row crop of choice here*.
Clear? One season, row crop at maximum yield.
If I want to do the green manure thing, I have to go to the field, plant the green manure of choice, wait a whole season during which I get no useful crop off that field, turn that into the soil, and then only the following season do I get any crop back for sale.
Clear? Two years, one crop harvested at sub-maximum yield, even assuming that magic happened to provide all the P and K nutrients (because the legumes don't fix those from the atmosphere the way that they do N). Utter best case, you can maybe fit an early green manure in before a late cash crop in the same year, but even then you're hoping that the weather's friendly enough to give you what amounts to two growing seasons in one year, hugely increasing your risk. So that's great.
How do we get more nitrogen per field, per green manure crop? More green manure years piled on each other? Not so fast. Even if we ignore the reduced number of crops per year delivery (kind of hard to ignore, but whatever), they don't do any other kind of supplementation beyond what was already in the soil, plus some putative benefits around soil texture and fibre. If we want to supercharge our green manures for nitrogen (and what the hell, increasing bioavailability of other nutrients, up to a point), we want to supplement to feed the green manure crop, and if we're trying to squeeze it into an early season or use a winter planting, they'll need some extra nutrients themselves, or watering, or other care depending on the local climate.
No goalposts need to shift here: green manures have well-known, well-publicised downsides including their limitations, allelopathy, and the limitations on time. Just multiplying green manure by a factor of 3 doesn't get you all of what you want, when and where you want it.
As for soybeans, you might want to look again. Just hitting the top of search results, check out https://agfax.com/2014/01/02/adding-nitrogen-soybeans-can-improve-yields/ [agfax.com] and feast your eyes on the bad news. High yield soy requires lots of surplus nitrogen, precisely because soybeans only fix so much, and that much is not enough for the top bushel/acre count.
Don't get me wrong. I use green manures myself. But usually in combination with their other benefits, and as part of a differentiated rotation strategy with weed and pest control in mind. But in terms of net agricultural production per acre they are an unambiguous loss compared to mineral supplements.
"The usual approach is to plow in the plants (usually not soybeans) before they seed."
Well, yes. We know. But if you're harvesting the seeds, you're not doing that. The soybean crop does minimal nitrogen benefit for the field.
(Score: 1) by khallow on Monday January 17 2022, @06:34AM (14 children)
Turns out green manure is indeed a third way as demonstrated in this thread.
(Score: 0) by Anonymous Coward on Tuesday January 18 2022, @04:33PM (13 children)
This is disingenuous.
The thread started with the rather oversimplified:
"Don't want to go vegetarian? You should have supported overpopulation initiatives 50 years ago, and it's not like you weren't warned."
This elicited the response from which you quoted, which reached far beyond merely nitrogen. This also came up later in the thread (for example, pointing out that legumes don't fix K and P from the atmosphere). Green manure does not solve the general nutrient problem at all, and in fact doesn't even really solve the nitrogen problem by itself, which actually supports the respondent's statement that:
"If you are able to get some of the population to give up meat, you reduce your source of eco-friendly fertilizer and increase your use of non-renewal sources."
It's important that green manures do not increase output, because in the context of vegetarianism, with its limited means of accelerating nutrient cycles we end up taking huge strides back in productivity, which quite simply means mass starvation.
If your only point is "Well, yeah, but legumes can fix nitrogen to boost your soil nitrogen levels without fossil fuels, even though you won't get the same returns, and you won't feed the world, and you won't even boost the soil if you harvest the legumes, and won't do much of anything for other nutrients at all, but they can totally fix the nitrogen!" then congratulations, you have a point that is as technically true as it is functionally pointless. If you were trying to position green manures as a way of actually feeding the world, you are demonstrably wrong about that.
In fact, I'd go further and say that you're even wrong about "green manure is indeed a third way" unless your criteria for success are at the laboratory curiosity level of relevance. A third way of technically introducing some bioavailable nutrients into the soil, sometimes, allelopathy notwithstanding? Sure. But in terms of sustainably feeding the world (the whole point of the original article) they're about as useful as urinating on a forest fire. Technically, it doesn't hurt, but practically it's not a solution. You choose to phrase it as "somewhat suboptimal" but in the real world in which people will be dying of starvation, that's rather like describing mediaeval approaches to cancer treatment as "somewhat suboptimal". They basically didn't meet the need. Green manures don't meet the need. They definitely don't solve the general case, and for sustainably feeding the world they don't even meet the nitrogen need.
But they do fix nitrogen. Woo. Sometimes. Under certain conditions. To limited extents. Break out the party hats.
(Score: 1) by khallow on Tuesday January 18 2022, @05:25PM (12 children)
Sorry, when someone writes
In fact, I'd go further and say that you're even wrong about "green manure is indeed a third way" unless your criteria for success are at the laboratory curiosity level of relevance.
We've already established it's providing half as much nitrogen as the leading way via fossil fuel-derived fertilizer. If that's lab curiosity level of relevance, then all nitrogen fertilizer is at the lab curiosity level of relevance.
It's interesting how even alleged experts often know little about their alleged areas of expertise isn't it?
(Score: 0) by Anonymous Coward on Wednesday January 19 2022, @02:20AM (11 children)
What part of green manure taking longer, fixing less, and either increasing risk by taking big bites out of the growing season or requiring extended fallow periods passed you by? It's not a laboratory curiosity because it doesn't work. It's a laboratory curiosity because on the scale of the original question (Can we feed billions without wrecking the planet?) it's a failure. It does not fix as much nitrogen as we would need, it does little or nothing for other nutrients, and you have provided precisely zero evidence to the contrary.
But you know what? You're the boss. You're king genius! You're about to prove us all wrong with your secret vetch/alfalfa mix that will do all the things, and you're going to absolutely clean house both agriculturally and financially.
Go on, genius, show us all how it's done.
"It's interesting how even alleged experts often know little about their alleged areas of expertise isn't it?"
(Score: 1) by khallow on Wednesday January 19 2022, @03:21AM (10 children)
Nothing at all. What passed you by was its relevance.
Perhaps someday you'll learn to use sarcasm well.
(Score: 0) by Anonymous Coward on Thursday January 20 2022, @04:32PM (9 children)
"Nothing at all. What passed you by was its relevance."
... to .... what? "Can we feed billions without wrecking the planet?"
No, the relevance to that did not pass me by. In fact, I reviewed it in that light. In fact, I did the sums and the answer came back dead in line with Betteridge: No. Feeding the world's population with green manure rather than other supplementation isn't a realistic prospect. If we drop to pre-supplementation technologies only, (no guano, no manure other than that of our livestock or ourselves, no potash or limestone mines, no calciferous sources other than bone meal) then we will have mass deaths to starvations counted in the billions and the authors of the original article are missing a good chunk of what made the Green Revolution even possible in the first place. Green manure doesn't change this, doesn't fix it, and at best could be considered a reasonably efficient take on fallowing strategies. Technically better than just letting weeds grow and deer graze? A little, sure. Enough to replace industrial supplement supplies? No, by a wide margin, and with a strong upper bound to the capability of the plants precisely because of the growing cycle and limited scope of broad plant nutrition supplementation, rather than a narrow band approach to nitrogen and fibre.
But maybe there's some other relevant factor that's in mind. Your abstract claim that green manure, specifically, is one way, technically, of fixing nitrogen, specifically, regardless of whether it is limited in its application (it is), insufficient for feeding the world absent other supplementation (it is), and has other significant downsides inhibiting its use (it does) such as constraining available growing seasons (it does), increasing weather/climate related risks in agronomic planning (it does) and places additional demands on supporting the green manure crop itself (it does).
This is a bit like trying to explain to freshly-minted marxists that Marx's ideas were founded in a world that doesn't exist any more, mostly existed as an oversimplified caricature even in his time, and consequently it's all a curate's egg. Even if they could conceptually work on some level, modern cooperatives don't prove their viability as such because they're too far removed from what he was talking about.
(Score: 1) by khallow on Sunday January 23 2022, @06:36PM (8 children)
You moved the goalposts. Originally, you claimed
When I mentioned green manure, you claimed
At that point, I noted that green manure already covers half the nitrogen delivery of "fossil fuels". That's pretty close already. At this point, I don't consider your protests interesting.
Moving on, there are two interesting emerging green manure technologies that I think will weaken your argument even further. First, microbe augmentation in soil. Basically, it involves finding microbes that will fix nitrogen for plants that aren't normally nitrogen fixing. For example: [futureofag.com]
Notice that this would also help cover your six week gap in legume nitrogen fixing, when it is applied to legume seeds!
Moving on, I think the other big technology will be cyanobacteria farming. A variety of cyanobacteria species can fix nitrogen. So in a sunny part of the world, turn sea water, air, and CO2 into nitrogen-rich bacteria ready to fertilize those fields, pretty much as a replacement for ammonia-based fertilizers.
(Score: 0) by Anonymous Coward on Sunday January 23 2022, @11:31PM (7 children)
Wrong AC, Bubba. I made no such claim. Nor would I; I'm well aware of a number of other strategies, including (but not limited to) green manure.
See, this is where the crazy comes in. "half" is not "remotely keeping pace". It's a runner being lapped twice on every lap they run. It's not "pretty close already". For a strategy that has been in place, with progressive refinements, before BP or Shell ever existed, it's firmly off the pace and there is no current prospect of a catchup with respect to turning a field to maximum yield. I don't care whether you consider my, or anybody's protests "interesting" or not; the world of production doesn't care either. You have a case to make? Go prove the big boys wrong, collect your Nobel Prize, and masturbate on CNN for all I care. Green manure ain't feeding the world, and even if you somehow magicked a fuckton of nitrogen out of it that ain't appearing now, without the growing season or other downsides that we currently know already exist in it because of fucking magic (good luck with that one!) you still haven't solved another damn thing, whether it's potassium or calcium or something less famous, such as selenium. Green manures do nothing worth writing home about for any of that, and have no prospect of doing so because you don't fix phosphorus from the air, nor potassium, nor calcum, nor iron, nor selenium, nor a whole bunch of other nutrients. As far as additional microbes, they won't fix any of the other nutrients I'd mentioned either because ... again, the air will basically give you carbon, nitrogen, oxygen, hydrogen and teeny-tiny bits of other stuff such as some occasional sulphur. Those microbes, by the way, had better fix nitrogen like turbocharged bunnyfuckers if they are to deliver maximum yield rates (and if you'd read some of the links I'd sent earlier you'd know that no green manure on earth does that right now).
Now I know you're not doing the homework. 14% on cotton over untreated is not impressive. Just check (because I googled this for you; it's fun and easy!) https://extension.okstate.edu/fact-sheets/cotton-yield-goal-nitrogen-rate-recommendation.html [okstate.edu] where the maximum yield rate is over 300% from a base level. Moreover they explicitly call out P and K nutrients as key elements. If 14% is their headline heartthrob number, they have a lot of work to do before I'd even roll out of bed for their stuff, let alone pay money.
Now I get that you're fixated on the holy grail of Nitrogen, and you're studiously ignoring all the other everything that the original story's author would call unsustainable and/or wrecking the planet, but your green manure fantasies aren't fixing that, and regardless of your miraculous fairyfart variety of clover that will suddenly give you abundant nitrogen a week after planting, or whatever, you're still mining like a demented kobold for other minerals - and we have no fix for that on the horizon. None. Doesn't exist.
Now, I breathlessly await your detailed description of a lichen that will miraculously transport potash across the Great Plains to fill our larders ...
(Score: 1) by khallow on Monday January 24 2022, @03:39PM (6 children)
Maybe you're the wrong AC, maybe not. I didn't see any "I'm a different AC" warnings in there. But if you really are a different AC, then keep up by reading previous posts. I'm not here to argue different straw men arguments every time a new AC decides to pipe up. Here, the straw man argument is that I'm somehow advocating for replacing all fertilizer, including non-nitrogen supplements by green manure. Didn't happen.
It's only a factor of three to keeping pace, remotely or otherwise. I'm not claiming that this is going to be just as perfect as using fertilizer, I'm pointing out how close it was in the first place.
Again. You're not going to get those elements from fossil fuels. Nobody made any claims about those nutrients and I explicitly noted earlier in the thread that I was looking at nitrogen only. The goalposts have been moved.
(Score: 0) by Anonymous Coward on Tuesday January 25 2022, @03:07PM (5 children)
The only goalposts shifting here are yours. The original (incorrect) statement was: "You can put the nutrients back into the soil in two ways. The 1st method that all you vegetarians love so much is processing oil into fertilizer. That is not sustainable. The 2nd option is to either graze herds across the crop fields or manually spread natural fertilizer (animal poop)." and this wasn't limited to nitrogen. Your response was: "You're just discussing nitrogen. Green manure is a third way, using a nitrogen-fixing plant or microbe to fix nitrogen from the atmosphere and then till that into the soil. Legumes, for example, are a great nitrogen-fixing group of plants and often generate a lot of economic value in addition to the nitrogen-fixing." which is a straightforward misconstrual of the original statement, and even within itself limited to the capabilities of nitrogen-fixers (which aren't up to what we can do with fossil fuels - again, check the mathematics) and in no way addresses all the other nutrients stripped by what the original poster called "effectively mining the soil for its nutrients".
Even if you want to try to retcon this as only being about nitrogen in your head because that's all that green manures will do for you, you're not solving the big problem, but in reality you're missing the point that it doesn't all have to be from fossil fuels as such if we're using fossil fuels to mine for things like limestone and phosphate deposits, making up for natural nutrient cycles that we have far outstripped. None of those massive mines constitute sustainable agriculture, most definitely not as the original article's author would have it.
Summary: if it's not just about nitrogen (as per the original poster, and the original article), then you're monumentally wrong. If it is just about nitrogen (as per your particular beef, which nobody else seems to follow), then the sums still don't work for you.
(Score: 1) by khallow on Tuesday January 25 2022, @10:00PM (4 children)
What part of "You're just discussing nitrogen. Green manure is a third way, using a nitrogen-fixing plant or microbe to fix nitrogen from the atmosphere and then till that into the soil." is wrong?
We don't have to use fossil fuels as such for things like limestone and phosphate. Just saying.
The problem word: "if". And the "sums" do work for me. I already said how.
(Score: 0) by Anonymous Coward on Wednesday January 26 2022, @03:43PM (3 children)
"What part of "You're just discussing nitrogen. Green manure is a third way, using a nitrogen-fixing plant or microbe to fix nitrogen from the atmosphere and then till that into the soil." is wrong?"
The original poster did not say nitrogen, but "Growing crops is effectively mining the soil for its nutrients." Nutrients. In fact, not even merely bulk nutrients (which might have been a reduced reference to NPK) but also includes others from sulphur to selenium. That is what is wrong, moreso because even if you had a magic legume that fixed all the nitrogen you'd need without a growing period of its own (spoiler: not even close), it wouldn't do diddly for the other nutrients on the list. It's like saying your car only needs gasoline, when in fact it also needs air, lubricant, coolant and so on - and everyone else is talking about fluid needs while you keep thumping a jerrycan.
"We don't have to use fossil fuels as such for things like limestone and phosphate. Just saying."
No, we don't. We can go back to pickaxes and pit ponies. You're right about that, but the prospect of doing so is minute, the cost would be exorbitant, and even if we mine it with cuddly bunnies and happy thoughts we're still exhausting mines rather than using a sustainable cycle. This seems to fall under what the original author would have called "wrecking the planet", because it becomes less welcoming as a place to feed ourselves.
"The problem word: "if". And the "sums" do work for me. I already said how."
Yeah, we already covered your problems there, whistling past the graveyard of why farmers aren't saving bank on urea because of all the problems with green manure.
(Score: 1) by khallow on Wednesday January 26 2022, @04:04PM (2 children)
Hence, my correction. You're welcome.
Or electricity from non-fossil fuel sources. I bet that would go further. Funny how you missed that one. Looks to me like you're too busy moving the goal posts to rationally think about this.
And we already covered how you acknowledged I was right in a backhanded way. I consider this finished.
(Score: 0) by Anonymous Coward on Monday January 31 2022, @02:57AM (1 child)
"Hence, my correction. You're welcome."
If only it were a correction. Instead, many other nutrients, untouched by green manure as a strategy, are of major concern. This is why your focus on nitrogen is so misleading; the green manure strategy does precious little for the larger problem, and depending on factors such as soil acidity can make it actually worse.
If that's your idea of help, please go help the Taliban. I understand they need all the help that they can get.
"Or electricity from non-fossil fuel sources. I bet that would go further. Funny how you missed that one. Looks to me like you're too busy moving the goal posts to rationally think about this."
Thus ignoring this part: "...even if we mine it with cuddly bunnies and happy thoughts we're still exhausting mines rather than using a sustainable cycle. This seems to fall under what the original author would have called "wrecking the planet", because it becomes less welcoming as a place to feed ourselves."
Funny how you mention moving goalposts in this context. I like 'em just where they are, so would you care to address the point at issue: the exhaustion of mineral resources and the damage involved in doing so?
"And we already covered how you acknowledged I was right in a backhanded way. I consider this finished."
... self-delusion aside, apparently the answer would be not. I mean, please, do feel free to farm all with green manure all the time and show us how to do it. Go on. Be famous.
But please do it for the Taliban, because we don't deserve your kind of help.
(Score: 1) by khallow on Wednesday February 02 2022, @02:05AM
Same goes for fossil fuels. You're not going anywhere with this.
Or open up new mines. Not seeing the point of your concern about sustainability since such exhaustion is a lot slower than the problems of population growth.