Soil Physical and Chemical Analysis

After sampling for 1 week, the soil was air dried for 5 days and sieved through 2-mm mesh to remove plant residues. Then, soil physical and chemical properties were measured according to previous studies (92 (link), 93 (link)). In general, soil pH was determined using a pH meter (FE20-FiveEasypH, Mettler Toledo, Germany) in soil water suspension (5:1 water-to-soil ratio). Total nitrogen (TN) was determined using a UV spectrophotometer (UV-1800, Suzhou, China). Total potassium (TK) in soil was measured using a flame atomic absorption spectrometer (AA-7000, Shimadzu, Japan). Soil organic carbon (SOC) content was assessed using a TOC-5000A analyzer (Shimadzu, Kyoto, Japan). The content of NH₄⁺, NO₃⁻, TP, and Olsen P in soil was determined by a continuous flow analytical system (Skalar San⁺⁺, Netherlands). The effects of waterlogging on soil chemical properties are summarized in Table S1 in the supplemental material.