Influence of soil properties and near-surface roots on soil infiltration process in short-rotation eucalyptus plantations in southern subtropical China

Abstract

Soil infiltration capacity is a measure of the rate of water infiltrating into a soil. The influence of soil properties and near-surface roots on the soil infiltration process remains unclear in short-rotation eucalyptus plantations. A series of field experiments were conducted to determine the soil infiltration capacities of differently aged (1, 2, 3, and 5 years) eucalyptus plantations by using a surface-positioned double-ring infiltration instrument. The biomass of fine root (<2 mm) and medium root (2–10 mm) on near-surface soil (0–50 cm) and soil samples (0–60 cm with 20 cm interval) was collected for analyzing the effects of near-surface fine root biomass (FRB), medium root biomass (MRB), soil organic matter (SOM), soil bulk density (BD), soil total porosity (TP), soil macroaggregate, and water-stable macroaggregate on soil infiltration. Results showed that the average infiltration rate (762–1463 mm h−1), initial infiltration rate (5420–8454 mm h−1, infiltration rate of stage I (3130–5421 mm h−1), infiltration rate of stage II (1594–2257 mm h−1), infiltration rate of stage III (484–934 mm h−1), and steady infiltration rate (318–510 mm h−1) increased with increasing forest age. The near-surface FRB (4.25–14.71 g) decreased with increasing forest age. Near-surface FRB showed a strong plugging effect on soil infiltration in both initial and steady infiltration stages, but this effect weakened with increasing forest age because of FRB decreasing. Near-surface MRB had no significant effects on soil infiltration. The TP and SOM in near-surface soil promoted soil infiltration capacity. The soil infiltration capacity of short-rotation eucalyptus plantations significantly improved after the third year of planting. Our finding contributes to understanding the effects of near-surface root biomass and soil properties on soil infiltration capacity in eucalyptus plantations, and provides a scientific reference for eco-hydrological study in such plantations.