Prior to the start of the experiment, the sieved and air-dried soilsamples were placed in a 50 L plastic bucket,flooded to a depth of2–3 cm (soil water content was 37.5%), and pre-incubated at 25 °C for14 days under dark conditions. After that, 20 g (dry weight) of pre-in-cubated soil were placed into 500-ml anaerobic bottles for the miner-alization experiment. Simultaneously, 110 g (dry weight) of pre-in-cubated soil were also placed into 500-ml plastic bottles fortransformation experiment. Deionized water was added to keep a2–3 cm water surface.