Why is one of the types of agriculture called slash-and-burn among the Slavs?

Slash-and-burn agriculture is a primitive form of land cultivation, in which the sown area for plant crops was freed up by burning forest plots. The ash left after the burning process served as an excellent fertilizer and contributed to an increase in the yield of sown crops. Slavic peoples practiced the slash-and-burn farming system until the middle of the 19th century.