PORTAGEVILLE, Mo.—We visit doctors regularly to maintain optimal health and perform at our best. We need to do the same for our farm fields, too. Gene Stevens, extension professor in plant sciences at the University of Missouri College of Agriculture, Food and Natural Resources, will demonstrate three diagnostic tools producers can use to gauge the health of their crops at the T.E. “Jake” Fisher Delta Research Center’s field day, Aug. 31 in Portageville.

Stevens will exhibit a portable pH meter, a refractometer and a Cardy meter at his field day stop. “One of the biggest fertility problems in Missouri is soil acidity, measured by pH,” Stevens says. “Most crops prefer pH levels above 6. Fortunately, pH is an easy test for farmers to do in the field with a meter about the size of a Magic Marker that can fit under most truck seats. The best way to correct acidity in fields is to apply lime in the fall.”

Producers can observe how the tools work and learn how they can turn the information gleaned from the tools into healthier plants, increased yields and optimal harvest times.

Stevens’ presentation comes after Chris Evans discusses sweet sorghum harvesting for biofuels. The refractometer Evans will demonstrate uses light to measure sugar content of sweet sorghum juice in a sweet sorghum plant. With that information, producers can get a good estimate of how many gallons of ethanol per acre their fields will produce and harvest at the optimum time—when the sugar content in the plant is at its peak.

Stevens also will discuss a new study looking at using defoliants to take leaves off soybean plants prior to harvest to get a more uniform harvest with less loss. “It’s not typical to do this on soybeans but common for cotton,” Stevens said. “However, we’re talking about $13 to $17 per bushel for soybeans, and at those prices every bushel counts.” The study will test three maturity groups and several varieties for the next few years.

Managed soybean, more money

For years, farmers using a corn/soybean rotation have devoted most of their time and resources to raising corn while leaving soybeans to scavenge the soil for nutrients, essentially “growing” corn and “planting” soybeans. David Dunn, extension associate at the Delta Research Center, said it’s time to reconsider that strategy.

From years of soil sample data and analysis, Dunn has discovered the penalties in yield loss for low phosphorus and potassium is actually greater in soybeans than corn. Furthermore, yield goals in the past 15 years have gone from 35 to 50 bushels per acre in soybeans, a 40 percent increase. In the same time frame, corn yield goals have only increased about 10 percent, from 190 to 210 bushels per acre.

As the price of soybeans increases and yield expectations go up, it’s time to evaluate the implications for soil fertility, Dunn says.

At this year’s field day, he’ll discuss yield data for P and K trials in corn and soybeans, advise producers on the differences between corn and soybean responses to lime, and discuss how to manage micronutrients in the soil for soil health and to achieve yield goals in both crops, while minimizing inputs.

For more information about the Delta Research Center, see