Soil health benefits of perennial biofuel crops on claypan soils

Claypan depth is one of the most significant drivers of variable soil productivity across different agricultural cropping systems in claypan soils, and the benefits of perennial biofuel cropping systems have been a topic of interest for decades. In general, perennial systems consistently exhibit higher soil health status than annual row crop systems due to greater above- and below-ground organic inputs and year-round soil cover. In this study, we evaluated the effects of long-term (14 yr) cropping systems including a corn (Zea mays L.) - soybean [Glycine max (L.) Merr.] rotation and two perennial grasses: switchgrass (Panicum virgatum), and miscanthus (Miscanthus x giganteus) across variable claypan depth categories (< 15 cm, 15–30 cm, and 30+ cm) on soil health indicators. Soil samples were collected at 0–15 cm from plots located in the Central Claypan Area of Missouri, USA, and a suite of 12 soil health indicators were measured. Analysis of variance and response ratios were used to examine the effects of cropping system and claypan depth on soil health indicators. Results showed that switchgrass and miscanthus systems had consistently higher soil health status than the corn-soybean system, with switchgrass demonstrating larger response ratios than miscanthus. Further, differences were enhanced in soils with shallow (< 15 cm) depth to claypan, for 10 of the 12 measured indicators. These results demonstrate the potential soil health benefits of long-term, perennial biofuel cropping systems, especially on shallow claypan soils.