K cost up for Brazil if you look at US$ vs Brazilian reais chart, you'll easily picture that this dependecy on imported fertilizer will hurt badly Brazilian economy.... high K --> high agro-products --> higher consumer prices --> inflation.
I don't think this explains today's "verde" close, but may explain future sp rise....
https://finance.yahoo.com/q/bc?s=USDBRL%3DX+Basic+Chart&t=1y
GLTA