Soil Chemical Properties Determination

Soil pH was determined with a water/soil ratio of 2.5/1. SOM, TN, TP, TK, AN, AP, and AK were determined as described by Zhou et al. (2017) (link). Briefly, SOM was determined by titration after wet oxidation with H₂SO₄ and K₂Cr₂O₇ (Heanes, 1984 (link)). TN, TP, and TK were determined using the Kjeldahl method, the molybdenum blue colorimetric method, and the flame photometric method (Analytik Jena novAA^® 350, Germany), respectively. AN, AP, and AK were determined by the alkaline hydrolysis diffusion method, the molybdenum blue colorimetric method, and the flame photometric method, respectively. ECa, AS, and EAl were determined by the atomic absorption spectrometry method, barium sulfate turbidity method, and spectrophotometric method, respectively.