CHICAGO, Aug 29 (Reuters) - Torrential rain from Hurricane Isaac, 20 inches or more in some areas, threaten the soybean and rice crops in the Deep South, an agricultural meteorologist said on Wednesday.
"Soybeans are vulnerable and rice may be the most vulnerable to damage," said Andy Karst, meteorologist for World Weather Inc.
The lumbering Category 1 hurricane was lashing the Gulf Coast with wind and rain, threatening to flood towns in Mississippi and Louisiana. There were storm surges of up to 12 feet (3.7 metres) and sustained winds up to 75 miles per hour (120 kilometres per hour).
The storm's rain is currently moving across the lush crop region of the U.S. Deep South, known as the Delta, but is forecast to reach crops in the central Midwest later this week and weekend.
A large amount soybeans, cotton, and rice are grown in the south, while in corn and soybeans are more common in the Midwest.
The Louisiana soybean harvest was 18 percent complete, Mississippi's 9 percent and Arkansas' 8 percent, USDA crop reports said on Monday.
All three states are receiving extremely heavy rain from the slow moving storm, which is forecast to become a tropical depression as it moves northward into the weekend.
Many cash soybean buyers in the south and in parts of the Midwest raised bids due to the slowed harvest and the potential loss of production.
Most of America's rice is produced where the eye of the hurricane is passing.
U.S. rice was 27 percent harvested as of Monday and most of the remainder had headed meaning it was nearly ready for harvest and susceptible to damage from flooding.
Don Keeney, meteorologist for MDA EarthSat Weather, told the Reuters Ag Forum early on Wednesday that he expected rice paddies in Louisiana to be damaged.
Keeney also expected substantial harvest delays in the Delta over the next three days and in the Midwest by the weekend.
"Just about all of the Delta will be affected from the storm but the biggest rains will cover Arkansas, Louisiana and southwestern Mississippi, covering about 75 percent of the Delta," Keeney said.
"The main issue in the Midwest will be the heavy rains."
Lighter rainfall, from 0.25 inch to 1.00 inch, can be expected by the weekend into early next week in far northern areas of the U.S. Midwest, meteorologists said.
U.S. harvests had already been slowed by showers this past week and rain from Hurricane Isaac should prevent any significant progress this week, especially in the central Midwest and Deep South.
The U.S. Department of Agriculture said on Monday that 6 percent of the U.S. corn crop had been harvested. It said 26 percent of it was mature, with most of that in the U.S. South and in the path of Isaac's torrential rainfall.
The USDA said 8 percent of the soybean crop was dropping leaves, or mature, and rice harvest was 27 percent complete. On the cotton, 24 percent of the crop's bolls were open and ready for harvest.
