Agronomists design Alabama Soil Quality Index

Professor Charles Mitchell of Auburn University's College of Agriculture Crop, Soil and Environmental Sciences Department and an Alabama Extension agronomist hopes the new Alabama Soil Quality Index will help farmers improve production and find new ways to conserve natural resources.

The index was designed to 1) make producers aware of soil quality/soil health; 2) suggest ways of improving soil quality/soil health; 3) use existing, low-cost, soil test methodologies; 4) use existing, routine, composite soil samples from producers; and 5) provide information in a simple, easy-to-understand manner.

“For 60 or 70 years now, we’ve been throwing fertilizer and lime on the soil, trying to help farmers get by on some pretty darn poor soils,” Mitchell said. “We thought we needed to do something to change that, so we came up with the Alabama Soil Quality Index.”

In Central Alabama cotton fields, most of what would be referred to as soil is actually just dirt, and organic matter in the state’s soils was almost nonexistent. A 2001 survey concluded that 55 percent of fields had less than 0.4 percent of soil organic matter. 

“In other parts of the world, our soils wouldn’t even be considered soils; they’d be considered simply ‘dirt',” Mitchell said. “By definition, soil must have organic matter.”

“The Old Rotation (circa 1896) experimental field on the Auburn University campus has shown that soils with less than 2 percent of organic matter don’t have a high yield potential,” Mitchell said. Old Rotation was important in the development of the Soil Quality Index, and researchers made sure to collect soil samples were taken from 300 other locations throughout the state for the basis of the index. 

Mitchell said the best time of year to take the sample is in the autumn but it is possible to take it any time of year.