Commercial agriculture is a gamble, and farmers spend most of the year hedging their bets. In Missouri and Illinois, that means deciding when to plant, how much seed to put down, what proportions of crops, and whether the choices are correct depends on the weather. 

As the sun beat down on cracked, drought-weary earth again Saturday — temperatures climbing quickly past 100 degrees for the tenth consecutive day — it seemed Mother Nature had not only drawn the winning hand in the summer of 2012 but held three aces. And the rain that fell Sunday may not be nearly enough.

Across Missouri and Illinois, the dual forces of record-breaking heat and historic drought, compounded by near-record low soil moisture levels, have forced many farmers to throw in the cards. 

Specialists from the University of Missouri Extension have estimated corn losses of 60 percent and hay losses of 75 percent across the state. Those numbers may be optimistic for some farmers in the southern portion of Illinois who have all but given in to scorching temperature and weeks without rain, according to Illinois State Climatologist Jim Angel.

"It's pretty critical," Angel said of the situation unfolding across the Illinois. "For many farmers, even if it started raining right now and rained two inches a week for the rest of the summer, I don't think it's going to help them out much. I think we're too far gone now."

Though a line of thunderstorms moved through the bi-state area Sunday, ushering in cooler temperatures and, in some areas, much needed moisture, the relief looks to be temporary. Weather forecasters say they see no significant pattern change in the near future. The drought of 2012 may just be getting underway.

A perfect storm

Intense heat and seasonal drought are not uncommon in the lower Midwest, where summer temperatures often rise into the upper 90s or lower triple digits and spot thunderstorms can be the only relief. But rarely do they start so early and in such force, experts said. The combination of that early drought and heat with a host of other unpredictable conditions have made for something of a perfect storm.

Much of the bi-state area began to experience drought conditions late last summer, according to Richard Hoormann, an agronomy specialist with Missouri Extension. In essence, that drought has never ended. 

"We are approaching last year," Hoormann said. "We had about 50 percent, half of normal (last year), and that was considered pretty hard to take, but that drought did not become significant until July. The drought that we have now started last year."

As a result, soil moisture levels entering the spring and summer growing seasons were low to begin with. And because warm, dry spring weather allowed farmers to plant their crops weeks ahead of schedule, what moisture remained was quickly used up.

At the time, the benefits seemed to outweigh any risks. Experts were predicting record yields when the growing season began, and farmers were looking at the potential for huge profits — profits that could partially offset losses of 2011.

So, farmers took the favorable early conditions and bet big. They sowed a record-breaking numbers of acres of corn and soy beans, the two major cash crops in the region. Some hedged and planted drought-resistant varieties of corn, others did not. Just another bet to be made on the weather. 

Then the rain stopped and the temperatures soared. Fields irrigated exclusively by rain water began to dry up. The already-scant soil moisture was used up and the earth began to crack. 

How great yield losses may actually be is hard to say, according to experts. With variations in weather between individual locations, blanket statements are largely inaccurate, and agronomics experts say the outlook changes daily. 

What is clear is that in the southern third of Illinois, perhaps the hardest hit portion of the bi-state region, many farmers have called it quits completely with corn crops and may do the same with soy beans. 

In Eastern Missouri, the outlook is very site-specific, but it does not seem promising.

"Right now, we're expecting county averages in the Warren/Montgomery area of less than 50 percent of yield and going down each day that we have over 100 degrees on corn," Hoormann said. "On soy beans we're probably at a 50 percent reduction; 100 percent of the crop will be impacted."

Hoormann, who is part of the Farm Service Agency in Missouri responsible for assembling a regular agricultural assessment for the governor, likened the drought to those occurring in 1988, 1980 and 1954. Its effects, while a long way from being fully understood, will be far-reaching. Cattle farmers, he said, have already begun to tap into hay stored for winter and sell off the livestock that their dried up fields can no longer support.

A stomatical dilemma

Among all the unfavorable conditions combining to make this summer's drought such a lethal one, timing may be the most important, horticulturists say. An August drought — like the one last year — can be overcome. By late summer, corn ears are already formed on corn plants, and bean pods already developed on soy. When the drought or heat hits, the plant will compensate by allocating more resources to those areas.

The problem, biologist Thomas Brutnell said, is that this year the drought and heat began before the plants had established their kernels and pods. As the heat has intensified in recent weeks, both corn and soy have entered critical flowering stages in their development, when the yield-bearing structures are formed. 

Brutnell, director of the Enterprise Rent-A-Car Institute for Renewable Fuels at the Danforth Plant Science Center, said any stress on the plant at this critical development stage directly affects yield. In the best case, that means fewer pea pods and corn kernels, in the worst, high heat can essentially kill the pollen and lead to lower fertilization rates.

It is too early to know how those rates will turn out, Brutnell said. Storms such as the one Sunday could help, as will lower temperatures, but the damage could already be done.

Plants that are fertilized face a stomatical dilemma going forward.

Stomata are the tiny openings clustered on the undersides of leaves that open and close to control gas exchange in the plant. Carbon dioxide necessary for photosynthesis must be brought in through the stomata, and oxygen, one of the bi-products of the reaction, must be let out. In other words, without this gas exchange, plants could not photosynthesize or respire, and they would wither and die, unable to create new tissue.

When the stomata open to facilitate the vital exchange, another coveted substance escapes with the outgoing oxygen: water.

"This is the big dilemma that plants face," Brutnell said. "You want to fix carbon, to create more biomass or grain, but in a drought, when they close their stomates, they can't bring in any carbon and their growth rate stops."

In other words, the hotter and drier it gets, the less incentive plants have to open their stomata. Photosynthesis stops and the plant ceases to grow. Evaporative loss is compounded by the sun's rays and the plant begins to wilt.

Brutnell said another key distinction between so-called C3 plants and C4 plants can determine a lot about how a crop deals with drought. Soy beans are a C3 plant and corn a C4 plant, meaning it is better equipped to handle the drought. 

Photosynthesizing consists of a sunlight-reliant reaction and a dark reaction, which does not need sunlight. In C3 plants, these two reactions take place in the same place. But in C4 plants, they are separated, with the dark reaction taking place in the protective tissue of the vascular bundle. 

That physical separation is very important, Brutnell said. It allows C4 plants to be significantly more efficient with their resources, notably the water and carbon dioxide necessary for the reaction. A more efficient photosynthetic reaction means the plant can open its stomata less frequently and, in turn, handle drought more ably.

For farmers who planted drought-tolerant corn seed, yields may be even higher. Those plants — developed, in one prominent instance, by St. Louis-based Monsanto — are more efficient in allocating scant resources and more adept at regulating photosynthesis. 

Drought-tolerant seed can lead to higher yields in drought years, but when conditions are right, its yield lags behind that of traditional seed. Once again, Brutnell said, it is all a matter of chance. A gamble.

One thing that is fairly certain, he said, is that abnormal weather events, be they extreme drought or heat, are likely to become more common as temperatures climb globally and the climate changes.

"I think what the farmers face now is more unpredictable weather events. The trend for decades ahead is hotter summers. The moisture is a lot harder to predict," Brutnell said. 

What's more, longer growing seasons will lead to more dilemmas like the one posed by this warm, dry spring. When should farmers plant? When should they call it quits?

"With climate change, we are definitely going to have earlier springs and later falls, and we really don't know the agronomics of that," Brutnell said. 2012 is the case in point.