By Sam Nelson
CHICAGO (Reuters) - Torrential rainfall from Hurricane Isaac hurt rice, cotton, soybean and sugar cane crops in the Deep South, but elsewhere the storm will bring relief to American farmers suffering from the worst drought in more than 50 years, an agricultural meteorologist said on Thursday.
"The (moisture) deficits are so great that it will take up to 10 or 15 inches of rain over a longer period of time to replenish soil moisture supplies," said Andy Karst, meteorologist for World Weather Inc. "However, this will help and it will bring some rivers back up and help speed up barge traffic."
Karst said the heaviest rainfall from the storm - up to 15 inches - was in southeast Louisiana, southern Mississippi and southwest Alabama. Two to five inches or more are expected on Thursday in central Mississippi and southeast Arkansas, he said.
"The heaviest rains were east of most rice and soybean areas, but there will be some damage from wind to rice and sugar cane crops," Karst said. Two to four inches of rain are expected in portions of the central Midwest through the weekend, he said.
Commodity Weather Group (CWG) on Thursday said some flooding losses could be expected for cotton, soybeans and rice. It also said the rains arrived too late to help revive the drought-stricken corn and soybean crops.
Rain from the lumbering hurricane is currently moving across the lush crop region of the U.S. Deep South, known as the Delta, and is expected to reach the central Midwest later this week and over the weekend.
Large soybean, cotton and rice crops are grown in the South, while corn and soybeans are grown in the Midwest.
Before the storm hit, the Louisiana soybean harvest was 18 percent complete, Mississippi's 9 percent and Arkansas' 8 percent, according to U.S. government crop reports.
All three states are receiving extremely heavy rain from Isaac, which is forecast to become a tropical depression as it moves northward.
Six percent of the U.S. corn crop had been harvested and 8 percent of the soybean crop was dropping leaves and ready for harvest.
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.
The storm hit the area where most of America's rice is produced. 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 wind and flooding.
(Reporting By Sam Nelson; editing by John Wallace)