tl;dw: There is a type of maize in Latin America that can self fertilize and nitrogen fix itself. Though a lot of this is popsci nonsense, they have been hybridizing it to a lot of success
How much nitrogen does it take out of the air?
If they're talking about bioengineering all crop plants to be able to do this, what will the environmental impact on nitrogen in the air be? And how will that impact the world?
There's plenty of nitrogen to go around, that's not going to be a problem.
Yeah that's what people said about fossil fuels 100 years ago. I'm not talking about now I'm talking about our environmental impact in the longterm and whether it is sustainable.
Ultimately we need to be getting ourselves to a state where we are essentially constantly performing geoengineering at a planetary scale to make our existence sustainable and stable.
I'm not saying we shouldn't. We obviously need food. I'm just curious what the actual impact is and how that would scale with all crops in the world. I'm certain there would be an impact and that something else would be needed to mitigate that impact.
Well, no, nitrogen leaving the atmosphere is just not a concern. Biomass of all plants: 500 billion tons. Biomass of all human crops: 10 billion tons. Nitrogen’s share of plant mass: 3-4%, or 400 million tons. Mass of the atmosphere: 5.5 quadrillion tons. And most of the atmosphere is nitrogen.
Nitrogen is 78% of the Earth’s atmosphere, and is necessary for all plant growth. Either we’re taking it out of the air to make fertilizer, or the plant is doing it themselves. Currently we mostly use natural gas to produce fertilizer (methane provides the hydrogen) and this would eliminate that need.
Also all of that nitrogen eventually makes its way back to the air, nitrogen gas is basically the most stable thing a nitrogen atom can be so eventually it makes it’s way back to that.
I'm a total amateur when it comes to chemistry so take this with a grain of salt, but I do have experience with nitrogen in a closed system...
The first thing that happens when nitrogen is depleted is a collapse of beneficial bacteria colonies. The bacteria that converts free ammonia into nitrite is the first to go, and shortly after, the colony converting nitrite to nitrate - the more usable form of nitrogen - follows. Finally, the plants that rely on these nitrates to grow begin to die off, creating a new source of ammonia in the closed system. The ammonia kills off vulnerable microfauna, leading to even more ammonia buildup and less potential food sources. Depending on the severity of the collapse, the cascade can continue all the way up to the macro fauna. In response to the newly available nitrogen in the form of ammonia from decomposed organics, however, the beneficial bacteria colonies will reestablish. Surviving microfauna will begin to decompose the dying plants and new growth will start to emerge once enough nitrates are again being produced. The new plant growth removes nitrates from the system, the surviving macro fauna reproduces and the system starts working its way back to stability.
But to get to this point, you still need an external source of nitrogen. Fertilizers, foods that the fauna can process into waste, etc. We're lucky in that nitrogen is available in extreme abundance, but I think you're definitely asking the right questions here.
If anything I could see it intensifying the problem. Normally nitrogen is refixed to the soil though crop rotation to legumes or green manure. That's at least some kind of variation of habitat and nutrients available to wildlife, some kind of period where corn pathogens in the soil have no plants to infect, some kind of non-corn additive to the soils, and the potential of more produce diversity for consumers. I don't like the idea of corn growing consecutively or across the whole area at once.
Evolution of nitrogen fixing outside of the legumes is really interesting from a plant physiology perspective, but we're also already swimming in staple grains to the extent that a ton are being wasted either directly (by not being utilized), semi-indirectly (through processing into low-nutritional-value foodstuffs that aren't necessary for a healthy diet), indirectly (by feeding to animals whose meat is then wasted), or doubly indirectly (processed into biofuel that is a net greenhouse gas emitter). While reducing our collective fertilizer footprint is great, we can do that by applying less/long release fertilizers and growing less damn
.Granted, this criticism doesn't apply to growers in poor areas who can't afford fertilizer but it's not like our global IP regime is really designed to get beneficial hybrids into their hands in an efficient manner.
