GRAINS-Corn firms, edges up from near 5-month low

* Corn firms for first time in four sessions

* Crop tour pegs Illinois corn yields below USDA f'cast

* Wheat edges higher, soybeans firm

SYDNEY, Aug 24 (Reuters) - U.S. corn rose for the first time in four sessions on Thursday, edging up from a near five-month low touched earlier in the session, after a widely watched crop tour reported lower yield estimates in a key producing region. Soybeans edged higher for a third consecutive session, while wheat also nudged higher. The most active corn futures on the Chicago Board Of Trade were trading up 0.2 percent at $3.56-1/2 a bushel by 0345 GMT, having earlier hit a low of $3.55-1/4 a bushel - the lowest since March 31. Corn closed down 1.2 percent on Wednesday and has slid more than 7 percent this month. The uptick in support came as the Farm Journal Midwest Crop Tour said Illinois corn yields are projected to fall about 6.6 percent from last year's near-record crop after surveying 205 fields across the No. 2 corn-producing state. The tour estimated yields in Illinois at 180.72 bushels per acre (bpa), below the U.S. Department of Agriculture's latest forecast this month of 188 bpa. "The surveys from this region needed to be poor for the market to retain its collective scepticism," said Tobin Gorey, director of agricultural strategy, Commonwealth Bank of Australia. The most active wheat futures were up 0.1 percent at$4.30-1/2 a bushel after closing up 0.2 percent on Wednesday. The most active soybean futures were up 0.3 percent at $9.41-1/2 a bushel, having closed little changed in the previous session. Soybeans were supported as Argentine biodiesel exports are expected to be priced out of the U.S. market after Washington decided on Tuesday to impose steep duties on imports that it said were unfairly subsidised. Gains were capped after the U.S. Department of Agriculture said private exporters cancelled sales of 640,970 tonnes of U.S. soybeans sold to China for delivery in the 2016/17 marketing year.

Grains prices at 0345 GMT

Contract Last Change Pct chg Two-day chg MA 30 RSI CBOT wheat 430.50 0.50 +0.12% +0.35% 484.46 14 CBOT corn 356.50 0.75 +0.21% -0.97% 379.18 23 CBOT soy 941.00 3.00 +0.32% +0.37% 972.42 47 CBOT rice 12.60 -$0.01 -0.04% +0.76% $12.48 59 WTI crude 48.37 -$0.04 -0.08% +1.53% $48.09 55


Euro/dlr $1.180 -$0.001 -0.05% +0.33% USD/AUD 0.7895 -0.001 -0.09% -0.15%

Most active contracts Wheat, corn and soy US cents/bushel. Rice: USD per hundredweight RSI 14, exponential

(Reporting by Colin Packham; Editing by Jacqueline Wong)