Growing season conditions may be the biggest contributor to poor crop appearance today, rather than inadequate soil fertility, says Fabián Fernández, University of Illinois Extension specialist in soil fertility and plant nutrition.
"Environmental conditions play an important role in nutrient availability," Fernández says. "Plants obtain most of their nutrients and water from the soil through their root system. Any factor that restricts root growth and activity has the potential to restrict nutrient availability."
Fernández says four factors may be causing this season's observed deficiencies.
"As growing conditions improve, most nutrient-deficiency symptoms will disappear without additional fertilization," he says.
In Illinois there are instances in which calcium, magnesium, sulfur and a few micronutrients may be deficient, but these deficiencies are not widely seen, he says.
"The use of micronutrient fertilizers should be limited to areas of known deficiency, and only the deficient nutrient should be applied," Fernández says. "Exceptions to this are situations in which producers already in the highest yield bracket try micronutrients experimentally in fields that are yielding less than would be expected under good management, which includes an adequate N, P and K fertility program and a favorable pH."
If a nutrient deficiency is suspected, he encourages producers to collect plant samples and send them to a laboratory for nutrient analysis.
When diagnosing a fertility problem through plant analysis, select paired samples of comparable plant parts representing the abnormal and normal plants. After collecting the samples, deliver them immediately to the laboratory. Samples should be air-dried if they cannot be delivered immediately or if they are going to be shipped.
Soil factors (fertility status, temperature and moisture) and plant factors (cultivar and development stage) may complicate the interpretation of plant analysis data. The more information provided concerning a particular field, the more reliable the interpretation will be.
"Because growing season conditions accentuate problems that might not be as evident in other years, this is a good time to learn about field conditions or management practices that should be adjusted to prevent or lessen problems in the future," he says.
For more information, check out The Bulletin, an online publication written by U of I Extension specialists in crop science.