How much fertilizer does the Iowan farmer need to add to their field to achieve that? How many years can they maintain that yield without eroding the soil?
How much fertilizer does the Iowan farmer need to add to their field to achieve that? How many years can they maintain that yield without eroding the soil?
Who cares? Fertilizer is nitrogen that literally comes out of the air. Erosion is vastly overstated by permaculture enthusiasts and can be mitigated vy changes to tillage and irrigation. Erosion in the Midwest clocks in at about 0.04 mm per year, but there's plenty of new soil deposition around the Mississippi. It's a manageable issue.
this is extremely wrong, but anyway back to my day because there is just too much wrong in this to respond to each wrong phrase
Extremely wrong how? There's a great an well sourced section in Vaclav Smil's How to Feed the World about this very topic. I also cited a specific erosion figure. But I guess that doesn't matter.
looking forward to reading it! definitely skeptical about your erosion rates, will have to go do my own research later (quick look, USDA estimates for the Corn Belt (~5 tons/acre/year on average)). if your info is coming from one book then i'm doubly skeptical, though i would bet that a soil scientist would probably agree with me and i'm def wondering if you might've misread the book?
i'm not a farmer, but i do manage woodlands, have a huge garden, volunteered on farms over the years, worked in a sustainable ag non-profit, and have even tried distributing sweet potatoes, etc, so i have an avid interest in agriculture and our food system.
aside from the fact that the soil is one of the three most important components for growing food, therefore it's extremely important to take care of it if we want our species to live into future centuries... there is a lot of evidence that shows that industrial ag creates erosion problems (one easy example: all of the national forests in my area was degraded farm land that they converted to woodlands in the 30s, because they learned this fact that hard way then). believing that hunger is a solved problem because of 20th century style agriculture is a fallacy. the dust bowl is one historical example that shows how this system can fail spectacularly, and it's all based in how we manage the topsoil, a natural resource just like oil or water.
we lost the moment we tried to overcome natural systems with chemicals (we've had a good run but i believe it's gonna be an anomaly in history). you can use science + natural systems in your favor to grow food. taking care of the topsoil is objective number one. food is a byproduct of good soil. the soil is a living system and chemicals kill that ecosystem to our detriment.
technology is definitely not the answer here. you are welcome to go try to grow food on mars without soil. good luck!
I initially copied the wrong number, the correct number is 1mm per year, coming from a Unas Amherst study not Smil’s book. It’s high vs pre industrial rates, but not catastrophic and as Smil points out there are plenty of places where land being farmed industrially is gaining soil.
How many years can they maintain that without petroleum inputs?
Ammonia can be generated through electrolysis as feed-stock for Haber-Bosch to get nitrogen, so literally forever. The reason we use petroleum is because it's currently cheaper than solar PV electrolysis.