For Illinois soybean farmers, soil pH plays a foundational role in crop performance, but the current liming recommendations used to manage it may be decades out of date. That’s the concern driving new research from Dr. Andrew Margenot and his team at the University of Illinois, supported by checkoff funding from the Illinois Soybean Association, Illinois Corn Growers Association, Illinois Fertilizer & Chemical Association, Illinois Certified Crop Advisers, and Illinois Farm Bureau. 

The goal: update Illinois’ liming guidelines to reflect modern soil testing practices and help farmers avoid both under- and over-application of lime—both of which can reduce profitability and soil health. 

Most soil tests today include buffer pH values, but Illinois’ official liming recommendations weren’t designed to use this data. As a result, farmers may be applying too little lime (risking soil acidification and yield loss) or too much (wasting money and materials). 

“Soil acidification can quietly chip away at yield potential and nutrient availability,” said Dr. Margenot. “This research is about giving farmers more precise, reliable guidance based on the data they’re already paying for in their soil tests.” 

The project combines controlled lab experiments and on-farm trials to recalibrate how buffer pH values are interpreted for lime application. Key components include: 

• Collection of 40 soils across Illinois with acidic pH to assess acidification in representative soil contexts. 

• Incubation studies on 24 representative acidic Illinois soils, with lime applied at a range of rates (0–6 tons/acre). 

• On-farm field trials across six sites in central and southern Illinois, where researchers are tracking crop and soil response to liming rates from 0–3 tons/acre. 

• Integration with national efforts via the Fertilizer Recommendation & Support Tool (FRST) to help align Illinois recommendations with broader standards. 

While results are still being gathered, the outcome will be a more accurate, soil-type-specific guide to interpreting buffer pH values. That means farmers can continue using their regular soil testing labs—but with much more confidence in what the lime rate recommendations actually mean. 

Once completed, this research will allow farmers to: 

• Fine-tune lime applications to avoid yield loss and unnecessary costs 

• Prevent long-term soil acidification that reduces crop nutrient uptake 

• Apply lime more precisely at the field or subfield level, depending on testing intensity