There is a world with flora and fauna based on the life forms that evolved on Gondwana (see here for previous questions). Humans colonized this continent from a distant one some thousands of years ago, before the advent of agriculture (similar to human colonization of Australia) and caused the extinction of most of the large mammals. The remaining megafauna has a few species such as elephants and giant sloths, but is heavily weighted towards birds and reptiles.
Now humans have developed agriculture in primarily tropical areas. I am using as a basis for development the actual human development of agriculture in sub-Saharan Africa. One of the biggest things that held back African agriculture was the lack of traction animals, to provide both plowing and manure. My people have a similar problem; there are no animals that they can domesticate to plow. However, the important part isn't the plowing itself (enough people with hoes can replicate that work) but the manure those animals create. Without the ability to fertilize monsoonal tropical soils, they become leached of nutrients. In Indian and SE Asia, water buffalo were around to chew up local vegetation and poop it onto fields; in Africa water buffalo were excluded by tsetse fly, fields lost fertility, and agriculture had to slash and burn rotating fields in the forest...a much less efficient proposition.
I want to replicate the manure creating effect of large domesticated animals like cows and water buffalo for a tropical region where there are no domesticated large animals.
The obvious answer might be composting; but composting has its own problems. First, compost takes at least a year, while cow's stomach takes a few days. Second, composting means lots of human labor to move things into a pile, then spread them out onto the fields. Cows move food into their stomachs then carry it into their stalls to deposit in piles; they also are used to drag the piles of manure out into the fields to spread them out.
What is the least human labor intensive way to generate tons of manure/compost to continually fertilize a tropical farm?
- Technology level is Bronze Age.
- You may assume any non-mammal, non-megafauna life form from Gondwana (South America, Africa, and Australia) is present.