Archer Daniels Midland Co expects average profit margins in Brazil's 2015/16 soy production to fall 77 percent from the previous season after two years of falling soybean prices, the company's South America president said on Monday. Valmor Schaffer projected profit margins of 122.20 reais per hectare, down from 539.03 reais in 2014/15, and said average margins would only remain positive because of a weakening Brazilian currency, which raises payment in dollars.