Farmers have a lot to live up to.

Last year’s bin-busting corn crop was the largest in the nation’s history. But can they do it again?

The U.S. Department of Agriculture thinks so. The USDA’s August forecast projected this year’s corn crop to hit 12.3 billion bushels with yields of 155 bushels per acre — the second-highest marks in history. Last year’s harvest was the largest, while farmers brought in the best yields in 2004. On the state level, the USDA expects Missouri’s crop to be one of the top five on record.

Northwest Missouri farmers could reap some good crops, but one expert worries that a wet spring may have taken a toll on the area’s upcoming harvest. Wayne Flanary, agronomist for University of Missouri Extension in Holt County, said many fields have shown nitrogen deficiency that will take the top off of yields.

Farmers apply nitrogen fertilizer to their fields before planting to give their soil a solid nutrient base, which leads to a strong crop. Frequent rains depleted much of that nitrogen in the spring, so fields that started strong could run out of gas late in the season when the nutrients dry up.

“That’s going to surprise some people,” Mr. Flanary said. “I hate to be negative, but you have to go with the truth.”

Increased demand from developing nations and the proliferation of corn-based ethanol have put the corn crop — and corn prices — into the unfamiliar glow of the spotlight. Prices broke records in the summer, drawing howls from the grocery aisles.

The Grocery Manufacturers Association blamed corn prices and ethanol for expensive grocery bills.

As farmers often say, the best cure for high prices is high prices. When everyone shoots for the good price during planting season, a big supply causes prices to drop.

Mike Geske, president of the Missouri Corn Growers Association, has already seen the price begin to fall.

“With production numbers on the rise, corn futures have dropped about $2 per bushel, but yet the price at the grocery store remains the same,” Mr. Geske said. “If what the Grocery Manufacturers Association and its members have been saying is true, then why haven’t food costs come down?”

Farmers can’t change the prices on store shelves, but they can boost the amount of corn they bring to market. Bioengineering has created hybrid seeds that fight through dry weather, resist insects and carry immunity to the weed-killing herbicides that many farmers use on their fields.

“We also have better knowledge of fertilizers, so the negative effect of corn-on-corn is minimized more,” Mr. Flanary said.

The technological advances — new hybrids come out every year — give farmers more freedom to break from standard crop rotation cycles so they can plant what the market demands.

As for this year, growers are left to watch the weather and hope for the best.

“We need some heat to push this late-planted corn crop all the way through,” Mr. Flanary said. “A good, nice, warm autumn would be very valuable for us.”

Agribusiness reporter Clinton Thomas can be reached at clintonthomas@npgco.com.