Plant–soil feedback pot experiment and significant potential factors validation experiment

We conducted a pot experiment to investigate plant-soil feedback mechanisms, utilizing soils from various crop rotation periods following Panax quinquefolius cultivation. The experimental groups were designated as follows:CK: Control group with soil that has no history of ginseng cultivation.A1: Soil from a field with 1 year of crop rotation post-ginseng cultivation.A10: Soil from a field with 10 years of crop rotation post-ginseng cultivation.A20: Soil from a field with 20 years of crop rotation post-ginseng cultivation.We aimed to identify significant potential factors, including pyruvic acid, fatty acids, and nutrients, through a validation experiment. The nutrient treatments were applied as follows:CK: Standard nitrogen (N) addition with a balanced ammonium N (AN) to nitrate N (NN) ratio of 1/1.INA: Inorganic nitrogen with a dominance of ammonium N (AN/NN ratio of 3/1).INN: Inorganic nitrogen with a dominance of nitrate N (AN/NN ratio of 1/3).ON: Solely organic nitrogen, supplied as 0.1 mmol L–1 glycine and 0.5 mmol L–1 tyrosine.MNA: Mixed nitrogen with a dominance of ammonium N; ON and INA were diluted and mixed to achieve a total N concentration consistent with the other treatments.MNN: Mixed nitrogen with a dominance of nitrate N; ON and INN were diluted and mixed to ensure the concentration of the total nitrogen component was consistent with the other treatments.For the replication of the experiments, CK, MNA, and MNN were represented by 20 replicates each, while INA, INN, and ON were more intensively studied with 40 replicates each.