Root morphological characteristics and soil water infiltration capacity in semi-arid artificial grassland soils

Surface water infiltration is an important process to meet plant water needs and an important part of the hydrological cycle via groundwater recharge, with special relevance in semi-arid regions. This study evaluated the relationships between grassland plant root morphological characteristics and soil water infiltration rates (IR: initial, steady and average). For this purpose, five artificial homogeneous grasslands (Melilotus suaveolens, Medicago sativa, Panicum virgatum, Bromus inermis and Miscanthus sinensis) without irrigation or fertilization were studied in the Loess Plateau. The observed steady IR were significantly different between the 1-year grasslands: M. suaveolens > M. sativa > P. virgatum > B. inermis > M. sinensis. The root length density and root surface area were negatively correlated with the average, initial and steady IR at different soil depths (p < 0.05). However, the root volume did not significantly influence IR. The stepwise multiple regression determined that the main factors controlling IR were the root length density at the depth of 5−30 cm and root surface area at the depth of 10−20 cm. Our results provide insight into the influence of grassland root morphological characteristics on water infiltration in drylands and are of interest for soil water supply programs in forage production.