Hurricane Isaac caused "intensive damage" to some southern US farms, and oppressive heat in the north, but proved just what some Corn Belt farmers wanted, bringing much-needed moisture.

The US Department of Agriculture said that, overall, crop condition showed little change in the week to Sunday, with the corn crop steady at 22% in "good" or "excellent" health, stuck at its worst readings since 1988 after summer drought.

The soybean "good" or "excellent" reading stayed at 30%, also the worst figure for early September of year since 1988, with that for cotton easing one point to 42%.

However, the stable headline readings disguised some significant changes in individual states as Isaac headed north after touching land in Louisiana, and leaving a trail of destruction estimated at potentially more than $2bn.

'Intensive damage'

In Louisiana itself, "some parts received intensive damage to field crops and pastures due to high water and heavy winds," USDA officials said.

The proportion of the state's cotton seen good or excellent dropped by nine points, to 72%, with, elsewhere in the south east, the Georgia crop tumbling 12 points to 54% placed in the top two ratings.

'Significant precipitation'

However, Isaac proved a boon to some more northerly farmers, after it's the strength of its winds and rains moderated.

"The remnants of Hurricane Isaac brought significant precipitation to the state," they said, noting that topsoil moisture levels were now at their best since mid-May.

"With the increased precipitation levels, soybean conditions improved a bit."

Some improvement was also seen in crops on some other important producing states, such as Kansas and Ohio, too.

'Fall tillage put on hold'

But the benefit was further offset by the high temperatures that Isaac caused in states beyond its path by raising air pressure, and taking temperatures back above 100 degrees Fahrenheit in some northern areas.

In Wisconsin, the condition of the soybean crop dropped four points to 40% good or excellent, with that in North Dakota tumbling eight points to 45%.

"Hot, arid conditions continued throughout the state last week," USDA staff in North Dakota said, noting that the dearth of moisture was spreading into autumn planting plans too.

"Fall tillage will be put on hold in some areas until moisture is received," a contrast with many others states, where Isaac has improved moisture in seed beds.

* Separately, exchange operator Ice Futures said that 2,000 bags of certified stocks of arabica coffee, stored in New Orleans for delivery against its futures contracts, had sustained water damage from Hurricane Isaac.