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"Forget the pig is an animal - treat him just like a machine in a factory" | Hog Farm Management magazine, 1976
(i.imgur.com)
EDIT: changed title to reflect that the original place saying the quote was the Hog Farm Management magazine rather than the Washington Post. The photo itself is from an article in the Washington post
How do you keep soil fertility up with no animal inputs?
Largely with the same main fertilizer used today, synthetic fertilizer (and ideally compost as well), but counterintuitively it takes much less synthetic fertilizer due to removing the large amount of feed grown. That's even compared to using as much manure as possible
https://www.sciencedirect.com/science/article/abs/pii/S0921344922006528
Synthetic fertilizers are essentially processed oil and we already know what the extraction, transport, processing and distribution of it entails.
Integrated farming, where animals are integral parts of a well planned farm operation present more advantages than drawbacks.
Animals help in manage soil and landscape (by eating plants that can easily out compete or swarm cultivation areas), can combat pests (chickens and other birds will eat pests naturally present in the soil and areate it in the process), provide fertilizer and can even compost and correct it (chickens and pigs can be used to turn manure piles), which implies less machinery employed.
Goats and sheep are superb at managing dry vegetation or any kind of foliage that can present a fire hazard. Pigs are natural soil plowers, capable of removing stones, stumps and deep roots. Chickens are good to level and clear soil, very fast, and excel at keep tree roots clean of weeds. Angola chickens can clear a field from ticks and other potential parasites very fast.
We do have other sources of soil nutrients that do not entail processing oil but the farmers are often not aware or unreceptive to it.
Yes, but it takes less synthetic fertilizer overall at scale per the earlier source even compared to using maximum amount of manure possible
That's not to mention crop rotation and compost as well which are methods that can still be employed to reduce fertilizer usage further on plant-based systems
The first issue we need to take is using synthetic fertilizer.
We already recognize oil is more of a source of problems than anything else: runaway methane leaks at the wells, soil polution, water polution, spills during transport, high energy consumption for processing, etc.
Manures are already available elements that only need to be reintegrated into the soil.
Composting operations also greatly benefit by having manures added to it (and manures technically require composting before use) as the bacteria from the animals digestive tract help breakdowm the material.
And yes, crop rotation and field management are essential but the more tried and tested techniques and resources we can use to shake away our dependency of oil, the better.
One lesser known source of nitrogen and phosphorous very under used: waste water management plants muds. Many countries are still sending precious resource for landfills.