Corn Argentina  The corn harvest had its biggest weekly advance since it started with 3.2 percent of fields harvested last week. That brings the total harvest accomplished to 10 percent of the area.  As the combines advance, low and very heterogeneous yields are being confirmed. Not only are yields below historical averages but they are also below what was expected a few days ago due to the lack of rain during critical periods. Of the unharvested area, 63 percent of the early corn is good to excellent, while the late corn is 95 percent good/excellent.  The Buenos Aires Grain Exchange last week lowered its production estimate from 51 to 49 MMT. This is in line with the 40-50 MMT estimated by most of the market. Truck arri...