The US Department of Agriculture reported on Monday that 14 percent of the US rice crop had been harvested as of Sunday, just behind the five-year average of 15 percent.
Farmers in the top US rice producing state of Arkansas had harvested only 1 percent of their crop, the government said.
CBOT rough rice futures ended on Wednesday down 4 cents per hundredweight to unchanged, with September down 4 cents at $7.65 and November flat at $7.58.
Rolling of CBOT September rice positions into November continued, with the September-November spread closing at 7 cents, premium September, floor traders noted.
Rolling of CBOT September positions was expected to continue before first notice day on August 31.
Open interest in CBOT September rice totalled only 429 lots before on Wednesday's open, down 132 contracts from Tuesday's pre-opening tally, brokers noted.
"Trade was extremely quiet, with some late speculative sales," one CBOT rice broker said.
Cash US rice trade was also reportedly quiet, traders said.
CBOT rough rice estimated futures volume on Wednesday totalled 76 contracts, compared with Tuesday's volume of 650 lots. Options volume was 17 contracts.