Recently a friend posted the Matrix-esque idea that humans are a disease that has been inflicted upon the earth. Sometimes it seems hard to disagree, but throughout history there have been clear counter-examples. For example, American Indians set fires that maintained grassland and savanna ecosystems in an otherwise forested landscape. This alteration of canopy structure (i.e. plants at different heights) promoted amazing pockets of biodiversity. These landscapes hosted many species that are now extinct or threatened in some way.
At least three types of agriculture ARE sustainable. (And by sustainable, I mean they could sustain civilizations for thousands of years) Delta systems (eg ancient Egypt), aquaculture systems (I think the best examples are in Asia, but I’m not sure on their longevity) and Integrated crop-livestock systems* eg. medieval Europe). The last one is basically the opposite of our current system: Corn everywhere, cattle on feedlots (neither near cities). In the old system:pasture everywhere, corn/grain/vegetables on food plots (near cities). The modern system took a lot of tricks to figure out how to make it work. It’s pretty wasteful and ends up contributing hugely to the Mexican Gulf’s dead zone.
So, here’s how integrated crop-livestock systems work: Grazing (in well-managed pastures) helps stimulate belowground root production. Through mechanisms we don’t totally understand, the nutrient cycling in the system changes. A positive feedback loop of higher nutrient availability, more productivity and still further increases in nutrient availabilty builds up over 4-10 years (the minimum seems to be around 4, but it’s clear if there is a cutoff for this nutrient build-up, though a look at the great plains would indicate not really). After a while (5 or so years), though, the process slows down so we convert a section of the pasture to crop production. These crops (and tillage) use up those nutrients. When the nutrients are used up, we convert the system back to pasture and start over.
There’s not enough data to be sure, but this system could probably produce *more* food (and *healthier* food too) than current systems. AND crappy former-farm wastelands (particularly here in the southeast) could be put back into grassland production. You may think “Oh, but nature will fix it better than humans” but you’re wrong about that. Without help from humans to restore those ecosystems, these farms are often covered with invasive species that make terrible wildlife habitat. Also, to rebuild the soil resources that we strip-mined, it takes dozens of years. With pastures, we can rebuild those soils in around 10 or so years.
So, there you are. By looking into the past we can find examples of sustainable systems that worked for almost a thousand years. An estimated 400+ million people lived in Europe (about 3.9 mil. sq. mi.) for hundreds of years without the benefit of fossil fuels. By comparison there’s about 300+ million people in the US (about 3.8 mil. sq. mi.) right now. Sure, we’re currently addicted to fossil fuels, but it seems like we should be able to figure this out.