Changes

Interestingly, in Japan and China, there was a different solution to the problem of human waste. In this case, there was a collection system where human waste was used to fertilize agricultural fields. In Western states, this did not develop because of the dependence on cattle, while in Japan and China cattle were not as integrated into the agricultural process.<ref>For more on using human waste as fertilizer, see: King, F. H. <i>Farmers of forty centuries: or, Permanent agriculture in China, Korea, and Japan</i>. Miami, FL: HardPress Publishing.</ref>

By the 16th and 17th centuries, it was determined that potassium nitrate needed for gunpowder could come from human waste. European cities soon used their public latrines as a way to collect materials that would then be used to create potassium nitrate used for gunpowder. This industry helped to create a way to recycle and remove waste from public areas, helping cities to become more health and grow by the late Medieval and early modern periods <ref>For more on the use of human waste for gunpowder, see: Cressy, D. (2013). <i>Saltpeter: the mother of gunpowder</i> (1st ed). Oxford: Oxford University Press.</ref>.