CBOT Called Mixed To Firm To Start; Focus On Midwest Harvest Yield Data; Brazilian/Australian Dryness

** AgResource Pre Opening Sunday Market Calls: Soybeans 1 cent lower to 2 cents higher, corn steady to 1 cent higher with wheat called 1-3 cents higher.     ** Sunday Weather & Market Comment Discussion: Opening week calls are mixed to firm on continued dry Brazilian weather forecasts, disappointing early Midwest yield reports and the expectation of improved Chinese demand for US soybeans at the start of the week. Traders will closely follow combine results.     Managed funds through the week ending Tuesday were short a net 119,000 contracts of corn, 84,000 contracts of wheat and 4,400 contracts of beans. Managed money was short 32,000 contracts of soymeal and long 100,000 contracts of soyoil, suggesting that the oil share…