A mesocosm‐based assessment of whether root hairs affect soil erosion by simulated rainfall

Although plant canopies are widely recognized to protect the soil and help mitigate soil erosion, recent research has shown that the majority of soil scour prevention can be attributed to the roots. Because roots are more difficult and time‐consuming to measure than shoots, research in this area has largely been limited to understanding the influence of large roots and/or whole root systems, and there is little understanding on how smaller root traits, such as root hairs, contribute to the root system's ability to mitigate soil erosion. Therefore, this study subjected a root hairless mutant (brb) of barley (Hordeum vulgare L. cv. Pallas) and its wild‐type (WT) genotype to simulated rainfall. The results showed that increasing root presence significantly reduced soil erosion, but the impact of root hairs was less clear. Soil detachment significantly decreased as root length density increased, with no apparent genotypic difference in this relationship. The brb root systems produced significantly thinner (0.8‐fold) roots and a higher percentage (1.1‐fold) of fine roots, with both traits previously associated with increased ability to mitigate soil erosion. However, brb mesocosms produced a similar quantity of eroded soil to WT mesocosms, suggesting that root hairs in WT plants could have compensated for their root systems' reduced ability to mitigate soil erosion. Highlights It is not known whether root hairs affect a root system's ability to mitigate soil erosion. Soil yield following simulated rainfall was compared for a root hairless mutant (brb) and its WT. Root traits of brb favoured erosion mitigation, but brb and WT mesocosms eroded to the same degree.