The findings, reported in Soil Science Society of America Journal, are part of the Conservation Effects Assessment Program, a federal program designed to answer questions about the impacts of agricultural practices on soil health and water quality. They give researchers a baseline on soil health so that changes in management practices – and their effects on soil – can be measured going forward.
Diane Stott, national soil health specialist for USDA’s Natural Resources Conservation Service and a Purdue adjunct professor of soil science, and Ashley Hammac, a postdoctoral research associate for USDA Agricultural Research, looked at soil samples from the Cedar Creek Watershed, which drains into the Western Lake Erie Basin in northeastern Indiana and is one of 17 study areas around the country. The soil in the study area is healthy, with scores on the Soil Management Assessment Framework (SMAF) – which grades soil using 10 quality indicators – quite high. Physical, chemical and nutrient component indices averaged 90 percent, 93 percent, and 98 percent of optimum, respectively.
There was no difference in soil health when comparing tilled vs. no-till fields, except when looking at hills. Toe slopes, the areas at the bottom of a hill, had higher physical, biological and overall scores than the soil at the summit of a hill. That’s likely because loosened soil at the summit runs downhill, taking nutrients and microbes with it.
The highest-rated soils were in land converted to perennial grasses. In many cases, these were agricultural fields in which farmers have gotten government payments to convert them to grassland because…