* Warm winter puts Illinois wheat crop at risk
* Soil moisture still seen adequate
* Warm, wet fall may have washed away fertilizer
CHICAGO, Feb 7 (Reuters) - Illinois, a key farm state in the heart of the Corn Belt, is basking in its sixth warmest winter in 117 years -- good news for residents who have not had to shovel snow but a red flag for some of the state's most productive businesses: farms.
Illinois and neighboring Iowa - also in the midst of a balmy winter - produce about a third of all the corn and soybeans grown in the United States, the world's largest exporter of both crops. Farmers in both states feel more comfortable when there is a substantial snow cover to ensure adequate soil moisture that can nurture crops through the region's hot dry summers.
Illinois state climatologist Jim Angel said soil moisture, thanks to autumn rains, remained in good shape compared to pockets of drought in nearby areas of the Corn Belt, notably the high-yielding northern Iowa/southern Minnesota border area.
But this winter in Illinois has been a polar opposite of last year's snowy, frigid season, Angel told Reuters on Tuesday.
Angel said the average temperature in Illinois for December and January was 33.4 degrees Fahrenheit (0.7 Celsius) , much warmer than the historical average of 27.2 degrees F. For January, typically the coldest month of the year, the average temperature was 31.4 degrees F, or 6.6 F above normal, making it the 13th warmest January on record.
Several southern Illinois locations hit a balmy 69 degrees F last month, including Belleville, Kaskaskia and Cairo.
"It's just odd not to deal with much snow and it feels like we are in this continuous late fall pattern," Angel said. "A big contrast to last winter."
This winter, the usual arctic blasts have stayed north of the central Midwest crop belt, affecting areas like Canada, Alaska and parts of Europe most intensely, he said.
Chicago snowfall for December and January totaled just 13.9 inches, half of the 27.3 inches that fell in December and January a year ago.
Still, he said, overall winter precipitation is near normal thanks to the earlier rains, with Illinois soil moisture in good shape and "not in any kind of drought" like the areas of Iowa and Minnesota. Statewide Dec-Jan average precipitation was 1.87 inches, which is 97 percent of normal.
The eastern part of the state was the wettest, a prevalent trend since the autumn and a fallout from La Nina, a weather anomaly that occurs every couple years. La Ninas often bring drier-than-normal conditions in the southern tier of the United States and wetter-than-normal conditions in the Pacific Northwest and the Ohio River valley, according to the U.S. Climate Prediction Center.
But farmers will remain wary until they see heavy spring rains or a sudden big snow like last winter's storms.
Iowa, Illinois and Minnesota account for more than 40 percent of the U.S. corn and soybean harvest. Minnesota is also known for its spring wheat crop and Illinois is among the top U.S. soft red winter wheat producers.
"There is some concern the about winter wheat crop," Angel said. "We've been so mild that winter wheat has not been able to harden off to the cold weather. If we get a batch of really cold air at this point in the season it might be vulnerable to damage."
Angel also noted that the warm, wet fall and winter raised the chances that fertilizers applied during the autumn may have been washed away and need to be reapplied in the spring.
The National Weather Service is now forecasting above normal temperatures and precipitation for February in Illinois. The NWS outlook for the February-March-April period also is calling for above-normal temps for the southern half of Illinois and above-normal rainfall statewide.