USDA ESTIMATES SOUTH AFRICA CORN CROP, EXPORTS The U.S. Agriculture Department forecast South Africa's 1986/87 corn crop at 8.50 mln tonnes, vs 9.50 mln tonnes last month. It estimated the 1985/86 crop at 8.08 mln, vs 8.08 mln last month. USDA forecast South African 1986/87 corn exports at 2.10 mln tonnes, vs 3.00 mln tonnes last month, and 1985/86 exports at 2.75 mln tonnes, vs 2.75 mln tonnes last month.