Public Service and Agriculture

Clemson Ag Service Lab contributes to Southern fertilizer study


Shannon Alford, director of the Agricultural Service Laboratory, joined colleagues from across the South to conduct a study of recommendations for phosphorus and potassium application on crops across the region.

The results are published in an article, “Variation in soil-test-based phosphorus and potassium rate recommendations across the southern USA,” in the June 2021 online edition of the Soil Science Society of America Journal.

“These recommendations are based on historical data, but political boundaries across state lines and other differences have led to varying nutrient recommendations over the years,” Alford said.

The project began with grant awarded to a colleague, Deanna Osmond, at NC State University, who invited Alford to participate in 2017. It investigates the differences and similarities among the P and K recommendations for particular crops across the Southern region.

“The project goals have evolved to update or harmonize recommendations through updated field trials and collaborative data collection,” Alford said. “Obviously, I am not involved in the field trials, but I have helped with data collection and verification.

Another goal of the group is to create a web-based fertilizer recommendation support tool for growers, which is still in progress and can be accessed at

Founded in 1936, the Soil Science Society of America is based in Madison, WI, and is the professional home for more than 6,000 members and 800 certified professionals dedicated to advancing the field of soil science.

Its journal publishes basic and applied soil research in soil chemistry, soil physics, soil pedology, and hydrology. It can be accessed online at