\n\n"}\n\nFood for man may also be considered as a compound of the original elements, of the qualities, combinations, and control of which, chemistry is daily adding to our knowledge; nor is it yet for man to say to what this knowledge may lead, or where it may end.
it\u2019s really funny to me that this half-assed response to Malthus, who believed that the inability to grow more food created what was basically an inescapable population limit, turned out to be totally correct.
\u201cwell, uh, maybe if we study chemistry a bunch we\u2019ll magically figure out a way to grow, like, 100 times as much food as we currently can\u201d
and then we did!
i read something about the early history of understanding of photosynthesis, and in the decades leading up to 1816 when the quote from OP was written, they pretty much figured it out:
\n\nRespiration and combustion:
\n\noragnic matter + oxygen \u2192 carbon dioxide + water + energy
\n\nPhotosynthesis:
\n\ncarbon dioxide + water + light \u2192 organic matter + oxygen
\n\nNot with this terminology. Some of the people involved worked with the phlogiston theory, phlogiston being pretty much negative oxygen, so they called oxygen \u201cpure air\u201d or \u201cdephlogistonated air\u201d. Lavoisier called it \u201coxygen\u201d though. And the name \u201ccarbon dioxide\u201d doesn\u2019t make any sense pre-Dalton, they called it \u201cfixed air\u201d or \u201ccarbonic acid gas\u201d. And nobody was talking about \u201cenergy\u201d in this context yet. And the term \u201cphotosynthesis\u201d really refers to synthesis of glucose, and they didn\u2019t know that\u2019s what was happening yet.
\n\nBut in their own terms they knew the reactions described above were happening. They knew the \u201cphotosynthesis\u201d part was happening at the leaves in light, and that respiration dominated in the dark.
\n\nAnd the plant nutrients were recently discovered, beyond a vague \u201cthey need something from the soil.\u201d This guy de Saussure was doing basically hydroponics in his laboratory.
\n\n\n\n\n\n\nDe Sassure did not trace the source of plant nitrogen convincingly, but he correctly concluded that the source of this nutrient is not atmospheric nitrogen gas, as Ingen-Hous (1796) and many others had believed.
\nThat\u2019s important because it seems like it may have led to the first big payoff from chemical knowledge, for agriculture. I\u2019m not thinking of industrial nitrogen fixation here, I\u2019m thinking earlier, the nitrate mining in the Atacama Desert in Chile. Of course people have long fertilized soil with manure and other organic fertilizer, but when and how did they realize that the \u201cChile saltpeter\u201d could be used for fertilizer? How sophisticated or difficult was the process to get nitrates from ore?
\n\nApparently they started mining it in 1810 (according to this source, though idk whether for fertilizer?). And exporting to Europe for fertilizer in the 1830s. So\u2026 like\u2026 how did they know how to do this and that it would help plants grow? I suspect the knowledge was pretty recent.
\n\nAnyway\u2026 a lot that I don\u2019t know here\u2026 but\u2026 I was reading to try and get a sense of what was going on in 1813. It was too early to directly observe chemistry making an impact on agriculture. But if you were attentive to intellectual stuff you could see the progress being made.
\n\nI wonder when obtaining nitrogen for fertilizer from the air, using industrial chemistry, was first imagined. Seems de Sassure could have at least thought of it, even though it would be another 100 years before it was executed.
\n\nBut like\u2026 ok, of course people have long known that crop yields are limited by the fertility of the soil, and you\u2019ve got to do all you can fertilizing it just to keep up with the depletion of the soil by crops. And around the time the quote in OP was written, was pretty much the same time they were actually figuring out what materials conferred \u201cfertility\u201d, and shortly before they started getting nitrogen from an inorganic source, the nitrate ores in Chile. The timing makes sense to me. The reasoning in the quote is half-assed but a much more detailed case could have been made at the same time, and I wonder if the author was drawing on another source that fleshed it out more.