* Chicago corn falls after strong gains, soybeans little changed * Concerns over dry weather in South America support prices (Adds details on fund positioning, updates prices) SINGAPORE, Jan 7 (Reuters) - Chicago corn slid on Thursday as the market took a breather after hitting its highest in more than six years in the previous session, although losses were limited as dry growing conditions in South America stoked concerns about global supplies. Wheat lost ground for a second session. The most-active corn contract on the Chicago Board of Trade (CBOT) lost 0.3% to $4.93-3/4 a bushel by 0314 GMT, having gained 0.7% in the previous session when prices hit a May 2014 high of $5.02-3/4 a bushel. Soybeans futures were flat at $13.61-1/2 a bushel and wheat gave up 0.2% to $6.46-1/2 a bushel. Dry weather continues to threaten soybean and corn yield prospects in Argentina, and labour issues in the South American country have added to concerns about supplies. The union representing Argentine port-side grain inspectors was to meet on Wednesday with agro-export companies to try to clinch a wage deal to end a strike that started on Dec. 9. Traders have begun adjusting their positions ahead of the U.S. Department of Agriculture’s next monthly supply/demand report on Jan. 12, in which the government will release updated estimates of U.S. and South American crop production and usage. Commodity funds were net buyers of CBOT corn, soybean, soymeal and soyoil futures contracts on Wednesday and net sellers of wheat futures, traders said. (Reporting by Naveen Thukral; Editing by Shailesh Kuber)