The US lifted the value of its farm exports to a record $145bn, as the last minute boost to the soybean crop, and sustained elevated prices, more than offset waning hopes for corn shipments.

Indeed, with lower prices of US food imports, such as cocoa, coffee and rubber, the US trade balance in agricultural commodities was upgraded to a surplus of $30.0bn, from a figure of $26.5bn, which would have been the lowest in four years.

The estimate for US exports of oilseeds, and products such as soymeal and soyoil, in the 2012-13 fiscal year was lifted by $3.3bn to $31.4bn, "propelled" by a 6.4m-tonne hike to 36.6m tonnes in the estimate for soybean shipments.

"Early September rainfall from hurricane Isaac contributed to higher [US] yields resulting in a significant rise in exportable supplies," the US Department of Agriculture said.

"Strong demand by China, coupled with limited South American competition has kept exports brisk while supporting prices at record levels."

US soybean export sales and actual shipments for the 2012-13 marketing year - which starts on September 1 for the oilseed, a month before the fiscal year – are running 24% higher than a year ago, despite a weaker harvest, being boosted by the dearth of alternative supplies in South America.

'Sluggish export sales'

However, the USDA ditched hopes of a rise in the value of coarse grain exports, which it downgraded by $1.4bn to $11.6bn, "due to sluggish corn export sales and weakening prices, amidst stiff foreign competition".

Combined US corn export sales and shipment volumes for the 2012-13 corn crop year, which also starts on September 1, are down 45% from their level at the same period last season.

The downgrade puts the value of US corn exports, unusually, in line with those of wheat, also pegged at $11.6bn, a five-year high for the grain.

"Although prices are down somewhat, values are still high from an historical perspective and expected to remain strong through the summer months."

'Weaker spinning industry'

The USDA also lowered further its forecast for the value of cotton exports, to $4.6bn, a 30% decline year on year, representing lower expectations for the volume of shipments.

"The decline in exports is in response to a slightly smaller US crop and falling global import demand, primarily in China," the USDA said.

"High domestic support prices in China continue to weaken the spinning industry."

The idea of slower Chinese cotton imports was backed by Barclays Capital, which cautioned that a revival in buy-ins last month, after six successive months of decline, did not signal rebounding trend.

"We anticipate muted cotton import appetite amid an uncertain macro-economic outlook," BarCap analyst Sudakshina Unnikrishnan said.