Time required for the wetting front to reach specific soil depths with different rainfall levels (hours).

Note: Three rainfall events were observed during the observation period in 2013 (11 years), i.e., moderate rainfall of 19.7 mm on May 17, heavy rainfall of 38.4 mm on May 25, and torrential rainfall of 73.1 mm on July 17. Beginning when the rain started, the times required for the wetting front to reach different soil depths were recorded. The data represent the mean ± standard error. Different lowercase letters within a column indicate significant differences (P Juglans regia)-wheat (Triticum aestivum) alley cropping system; JRMS: walnut monoculture system; TAMS: wheat monoculture system.Time required for the wetting front to reach specific soil depths with different rainfall levels (hours).