6H2O + 6CO2 ----> C6H12O6+ 6O2
Last night I happened to turn on MPR and was fortunate enough to hear a great interview Terri Gross did with Michael Pollan. If you get a chance, look for it on the internet and give it a listen. In any case, what really struck me about the conversation was his idea that we must "resolarize" our agricultural systems. This is something that has, as we, in the northern hemisphere, daily tilt closer to the sun, causing the days to lengthen, been on my mind quite a bit recently. By the end of February there will be about twice as much solar energy hitting the suface of the earth, here in Minnesota, as there was on January 31st. That solar energy will create changes in the weather patterns and, as some of it is radiated off of the various surfaces it hits, things will begin to warm. This warming, and the winds it creates, will change our weather and allow us to trade our snow boots for flip-flops and will melt the snow, exposing the ground, allowing us to begin planting. So, what's the deal with the oversimplified reaction in green above? Well, that's the foundation of my job and that is the "miracle" that you can thank for all of your favorite (and least favorite) meals; without photosynthesis, not much would be happening on this big rock of ours. While we are busy debating our shift to a new "solar" economy, the truth is, it always has been, and always will be solar, whether we like it or not! All that oil (a hydrocarbon...loaded with carbon atoms which, when combusted, joins with oxygen to form CO2) that we are pumping out of the ground... it too was, at least partially, created by solar energy! So what's the problem then? Well, it took gazillions of life forms billions of years to pull all of that Carbon out of the atmosphere (the 6CO2 on the front side of the reaction) in order that we "higher" organisms could have an earth that would support our biology. Actually, that statement is backwards. Our biology could only exist AFTER the CO2 was sequestered below the surface of the earth through a mixture of photosynthesis and other geological events. In any case, the main point is that this "simple" reaction deserves far more respect than it gets.
So, what does the reaction mean? Simply, it means that, through the photosynthetic process, 6 molecules of water and 6 molecules of carbon dioxide are combined to form one molecule of sugar and 6 molecules of atmospheric Oxygen. Why is this a big deal? Well, if you like either breathing or eating, two of my favorite things to do, without photosynthesis you would be out of luck!
Have you ever wondered why most plants are green? If asked, most of us will answer, "because they are filled with chlorophyll." Well, why is chlorophyll green? Its green because the wavelengths of light that make up "green" to our eyes are not being absorbed. So what?!? Well, the rest of the spectrum that managed to travel through space and strike our earth IS absorbed. What happens then? Some of that energy is used by reactions in plants' chloroplasts (the organelle that contains, among other things, chlorophyll) to split the Hydrogen from that water molecule (H2O), mentioned in the reaction above, and combine it with the carbon dioxide (CO2) to form simple sugars (C6H1206). Notice that, in combining water and carbon dioxide, we began with 12 Hydrogen atoms,18 Oxygen atoms, and a 6 Carbon atoms. The sugar has 6 Carbon, 12 hydrogen, and 6 oxygen atoms. That leaves the 12 remaining oxygen atoms to form 6 O2 molecules. The plant doesn't "need" this O2 and releases it. O2 is the plant's WASTE! Breathe deeply and smile at the nearest plant! If only our factories were as clean! Plants are able to take these two simple and abundant molecules and use them to store the energy from the sun, which they cannot directly use, as C-C bond energy in the sugars they produce. This energy can then be released through glycolosis and other metabolic processes used by plants and animals. Yippee! The sun could hit our skin all day long and we would still not be able to do this. We are very efficient at breaking these sugars down in order to run, or breathe, or dance the cha-cha, but we cannot make them ourselves and all life depends on their existence.
Agriculture, then, is all about organizing the plants to function in a way that puts their photosynthesis to use in order to feed ourselves. It is about harnessing solar energy. Michael Pollan made the point that modern "industrial" agriculture has been about not being content to just use the energy that is entering the system on a daily basis from the sun. It is about adding to the system the "ancient" solar energy, which is embodied in oil, to get even more out of our fields. We use oil not only for agricultural machinery and transportation, but also to create fertlizers to boost the amount of energy entering our agricultural system. While this has given us an abundant supply of cheap food, it is a little like squandering an inheritance. It is living beyond one's means and science is telling us that it is causing a whole host of problems that we cannot delay dealing with. So, if you are on the lookout for a miracle, and the virgin of Guadalupe appeaping on a piece of toast won't cut it, head over to your nearest potted ficus or spider plant and say, "Amen!"