By Michael Hirtzer and Karl Plume
CHICAGO (Reuters) - Indiana farmer Brian Scott saw on Thursday the heaviest rains of the year soak his 2,300-acre farm in the throes of the worst drought in five decades, but they were a mixed blessing at best.
The downpour came too late for his corn crop, which was already past the critical stage of setting yields. His soybeans, though, could get better and set more pods.
For growers like Scott across the U.S. Midwest farm belt, even unexpectedly heavy rains like the one on Thursday are coming too late for their corn crop to recover from the drought.
Many farms in the Midwest have not seen any measurable rain for a month before Thursday's storm dumped 1 inch or more of water across a large swath of northern Illinois and parts of Indiana.
"The corn, especially, has already taken quite a bit of damage. The rains can't improve the corn crop but it can still help the beans," said Scott, who farms with his father and grandfather outside of Monticello in central Indiana.
The U.S. Department of Agriculture last week slashed its U.S. corn yield by an unprecedented 12 percent to 146 bushels per acre from 166 bushels as crop ratings tumbled to the poorest since the drought of 1988.
TOO LATE FOR CORN
In the top corn growing state of Iowa, the 1.1 million corn acres rated "very poor" by the government are likely a total loss, with the crops in the poorest shape on the hillsides or growing in sandy soils that prevented the plants from tapping subsoil moisture, said Roger Elmore, extension agronomist at Iowa State University.
In eastern and southern Midwest, where the drought conditions are most severe, some farmers were already gathering poorly pollinated corn plants for animal feed or plowing down plants that will yield no grain.
"It's getting pretty late in many areas, so it's going to be tough to do a whole lot of good even if we do get a turnaround," said Joel Widenor, agricultural meteorologist with Commodity Weather Group in Maryland.
Seventy-one percent of the U.S. corn crop was pollinating as of Sunday, compared to the five-year average of 36 percent, USDA said.
Of the top 10 corn producing states, Missouri and Indiana were suffering the most, with just 7 and 8 percent, respectively, of the corn crops in good or excellent condition, compared to the five-year averages of 56 percent for each, according to the USDA.
The entire state of Missouri was declared a disaster area due to the drought and the U.S. Agriculture Secretary Tom Vilsack on Wednesday declared areas of eight other states disaster areas, including parts of Indiana and Arkansas.
There was a chance of rain in the next week that could help boost yield potential in Missouri, said Max Glover, a University of Missouri extension agronomist based in Shelby County.
"They certainly won't achieve full yields but they will escape having to feed the stalks to the cows," Glover said.
Some fields may produce only 20 to 40 bushels per acre of grain, compared to the average yield in the state last year of 114 bpa. However because of the blistering drought, demand for forage was strong due to poor pasture conditions, Glover said.
"There are some fields in Indiana that will provide near zero grain whether or not it rains this week," said Tony Vyn, extension agronomist at Purdue University.
Minnesota was in the best shape by far, with 67 percent of the state's corn crop rated good to excellent.
BETTER SOY OUTLOOK
A Reuters poll this week estimated U.S. corn production down nearly 7 percent lower than the latest government estimates while soybean production was seen 3.6 percent lower than the more recent USDA guidance.
"Corn after it's pollinated isn't a reversible thing," said Elwynn Taylor, a professor of agriculture meteorology at Iowa State University. The corn plant can put more weight into the kernel if it receives rain but it cannot improve a poorly formed ear.
Soybeans can generate new growth and rebound if they receive more rainfall. However due to early planting, the clock is ticking for the plants to form pods of soybeans before more heat arrives during what are typically the hottest days of summer in late July and August.
"While we remain more optimistic about soybean prospects than about corn, soybean yield potential is beginning to decline as more time passes without enough water to keep plants functioning well," said University of Illinois extension agronomist Emerson Nafziger.
Drought conditions are also expanding to the northern and western Midwest -- areas that earlier in the season had fared better, leaving some crop experts hopeful that they would help blunt shortfalls in the eastern Midwest.
"Iowa, Minnesota, South Dakota and Minnesota are the areas right now that have the most to lose, or the most to gain if we get rains," said Andy Karst, agricultural meteorologist with World Weather Inc in Kansas City.
"We wouldn't have to restore the soil moisture to help the crops out. If you get a good soaking rain followed by timely rains from here on out it could be OK even if the soil moisture remains low," Karst said.
(Reporting by Michael Hirtzer and Karl Plume, additional reporting by Sam Nelson;editing by Sofina Mirza-Reid)