• Lyrl@lemm.ee
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        9 months ago

        The energy input is the sun, and most of the calories come from the air (carbon dioxide). Given so much external input, harvesting from a plot without reducing soil fertility is totally possible. With nitrogen-fixing crops (soybeans being the poster child), even the nitrogen fertilizer comes from the air.

        • Lyrl@lemm.ee
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          9 months ago

          The plants use energy from the sun to turn carbon dioxide from the air into edible calories. When our animal bodies “burn” the food we eat, that turns it back to carbon dioxide, which we exhale.

        • KillingTimeItself@lemmy.dbzer0.com
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          9 months ago

          not a scientist here, but i imagine it’s a combination of different forms of energy/material and how different organisms utilize them. Plus the basic fact that nothing is ever perfect. We consume food, a lot of those nutrients are burnt for energy. Our brain consumes a significant majority of what we eat. Stuff has to go somewhere for things to happen.

          • calcopiritus@lemmy.world
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            9 months ago

            Not all the matter in farming fields come from fertilizer. A lot of it comes from CO2 in the air, which will eventually go into some plant that we can eat. Also, all those ways that matter is lost, therefore not being 100% efficient doesn’t make matter disappear. Burning turns it into CO2 -> it will reach a plant. Excrements going into water streams -> plants will pick them up, or ocean wildlife will pick them up. Buried corpses -> microbes and plants will pick them up. The only way to “lose” matter is for it to leave the atmosphere into space or to be buried so deep that no life can reach it.

            The atmosphere loses matter at a rate that is (presumably) not affected by human actions.

            Matter buried too deep is compensated by matter coming out from volcanic eruptions.

            As long as the earth’s core is hot enough for volcanic activity and the sun doesn’t run out of fuel, the cycle keeps going.