Connections between roots and soil health across agriculture management practices
Eric Britt Moore, Mriganka De, Márcio Renato Nunes, Debasish Saha, Virginia L. Jin, Lidong Li, Jane M. F. Johnson, Douglas L. Karlen, Marshall D. McDaniel
Abstract
Farmers are increasingly interested in regenerating soil health after centuries of soil-degrading practices. However, the most effective soil health regenerating practices (SHRP) and underlying mechanisms that regenerate soil health remain unclear. Our objectives were to determine: (i) how agriculture management, hillslope position, and their interactions affect soil health and root characteristics, and (ii) if there is a relationship between management-induced root characteristics and observed improvements in soil health. Soil and plant root samples were collected from 0 to 120-cm from three management practices: conventional maize-soybean rotation (Row Crop), cattle-grazed pasture (Pasture), and restored grassland (Grassland). Soil health indicators (SHIs) that are responsive to management differences: soil organic carbon, potentially mineralizable carbon, permanganate oxidizable carbon, beta-glucosidase activity, total nitrogen, and autoclaved citrate extractable protein were measured, along with root mass, root mean diameter (RMD), and root length density (RLD). Overall SHIs for Pasture and Grassland increased by an average of 54% and 41%, respectively, when compared to Row Crop. Pasture and Grassland management also had twice the root mass as the Row Crop systems. Pasture had the greatest proportion of very fine roots (< 0.2 mm RMD), while Row Crop had the lowest proportion. Individual biological SHIs showed the best negative correlation with RMD and were positively correlated with RLD. Soil health regenerating practices that increase total root mass, and fine root mass in particular (i.e., Pasture and Grassland), can lead to vast improvements in soil health regardless of hillslope position.