Quality or Quantity? Determining the Impact of Fine Root Traits on Soil Health in Row Crop Agriculture

Fine root production is closely related to nutrient cycling and can therefore provide implications for improved soil health, particularly within agricultural systems. Currently, it is unknown if fine root quantity or quality (carbon (C) and nitrogen (N) composition) has a larger impact on soil labile C and N pools within corn-based cropping systems. This study aimed to (1) investigate the effect of tillage intensity and crop rotational diversity on fine root production; and (2) evaluate the influences of fine root quality and quantity on soil health indicators. Fine root quantity, fine root quality, and soil health indicators that represent labile C and organic N pools were measured at two 50-year-old long-term trials with contrasting soil types; silt loam (Wooster) and clay loam (Hoytville) in Ohio, USA. Each site had varying tillage intensity, no-till (NT) and chisel (CT), and ranged in crop rotational diversity, corn-soy (CS) and corn-forage-forage (CFF). Findings indicated that fine root N was significantly greater in CFF-NT systems compared to all other systems (p = 0.05). In addition, fine root N had a significant and positive relationship with autoclaved-citrate extractable soil protein at Hoytville (r = 0.81; p = 0.004). Fine root C had a significant but negative relationship with N-acetyl-beta-glucosaminidase (NAG) activity at Wooster (r = - 0.57; p = 0.05). These findings reveal that perennial legumes are essential for enhancing soil health in row crop systems because of their ability to augment soil organic N pools via fine root quality.