Silica, Be Dammed!

Abstract

It took us about 180,000 years but finally we did it. We hit Earth’s carrying capacity for hunters and gatherers. That happened more or less 10,000 years ago and in order to keep going forth and multiplying, humanity had to learn how to farm. Talk about a multidisciplinary endeavor. There were plants and animals to be bred, tools to be designed, materials to be discovered, and a whole lot of biology, chemistry, hydrology, geology, meteorology, ecology, and biogeochemistry to be mastered. We’re still working on it (and have added mechanization, transportation, refrigeration, genetic engineering, electronics, and information technology, among other things, to the list). Needless to say, our early stabs at farming were nowhere near as fruitful and reliable nor as intensive and destructive as the farming we do today. But as we slogged through the millennia, growing ever better at farming, ever more of us could be fed. So our numbers kept increasing. Do you see the vicious circle? As long as the human population keeps growing, so must the production of food through farming so that at least some chunk of the population that there has been enough food to produce doesn’t then starve to death. For a long time, much of the getting better at farming meant increasing our control over the landscape and in no small part this was through damming. It also meant increasingly disrupting the biogeochemical cycles of nitrogen and phosphorus in our quest to keep cropland fertilized and productive. Both of these activities have had profound effects on the silica cycle.