Illinois Fertilizer & Chemical Association
Supply · Service · Stewardship

Corn and soybean crops limp towards the finish line

After the worst start to a cropping season in decades, mid-season lack of rain in parts of Illinois, and season-long low crop ratings, it’s time to take a look at what comes next as the 2019 cropping season moves into its final stages.
To no one’s surprise, various crop tours in recent weeks have confirmed that corn yields in parts of Illinois are likely to be disappointing. If there is a positive, it’s that the crop may look a little better than we thought it would by now after more than half of it was planted after June 1. While canopy cover and color in early July were a little better than expected, lack of rainfall and a less vigorous root system on late-planted corn meant that water stress began to show up in July. In areas where the dryness continued through August, some fields now show little green leaf area, and ear tips have dropped in drier parts of fields.
The driest parts of the state are the counties around the Quad Cities and in east central Illinois, with rainfall totals in July and August only about half of normal in these areas. This region shows up as being abnormally dry or in moderate drought on the U.S. drought map. Much of northeastern and southern Illinois received at least normal rainfall amounts over the past two months, and a band from St. Louis east along I-70 in south central Illinois shows rainfall totals of 150% or more of normal. Although late planting has gotten most of the attention, rain amounts, including lack of rain in some areas, will be a big part of the 2019 cropping story. That would have been the case even if planting had been early.
Late planting made the lack of adequate water a bigger problem. Many fields showed early water stress symptoms, and ended up with shorter-than-normal plants; both point to soil compaction as a major issue. Soil compaction was certainly an issue this year, but the smaller root systems and drying soils meant that plants weren’t as able to get access to water deeper in the soil as they would have been with earlier planting, even into compacted soils. Soil compaction is always present after tillage and planting using heavy equipment, but roots of early-planted corn can usually make connections to tap water from deeper in the soil even when there is compaction.
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