Slash and Burn's Effect on Soil

[Jayson]

https://www.quora.com/How-is-the-Amazon-...rests-soil

The Amazon rainforest soil is a dense white to white-yellow clay, not sand. When the farmers/ranchers slash and burn, the ash from the burnt rainforest trees allow a year or two of crops (such as soybeans) to grow, but by the third of fourth year this soil amendment is depleted and the farmers move on to another block of land where the slash and burn has been repeated.

Not a good idea. Has anyone encountered this style of farming? Is there outrage against it where you live?