The Effect of Different Soil Amendments on Soil Properties and on the Morphological and Physiological Characteristics of Chinese Cabbage

Excessive fertilization is one of the major challenges in Chinese cabbage production. Although various soil ameliorants have been widely applied in agricultural production, their underlying mechanisms of action remain unknown. Five fertilization treatments were tested under field conditions, including chemical fertilization (CK) and reduced chemical fertilization applied in combination with biochar (T1), microbial agents (T2), organic fertilizer (T3) and silicon-calcium-magnesium-potassium (SiCaMgK) fertilizer (T4). The growth, yield, root properties and physiological quality of two varieties of Chinese cabbage and their rhizosphere soil properties were measured to determine the effect of each amendment. Although biochar and other amendments had no significant impact on cabbage yield, the physiological analyses revealed that compared with CK, biochar application enhanced the vitamin c (VC) contents and soil urease and invertase activities by 25.34%–49.58%, 3.75%–10.08%, 42.71%–103.19% and respectively, in the two varieties of Chinese cabbage. Compared with CK, organic fertilizer application significantly increased peroxidase (POD) activity and soluble sugar and soluble protein accumulation and decreased the malondialdehyde (MDA) content in the two varieties of Chinese cabbage. The yield of Chinese cabbage was affected mainly by soil urease activity, superoxide dismutase (SOD) activity and MDA content. The VC content may have been regulated by the soil invertase activity and the root morphological parameters of the plants. We conclude that biochar and organic fertilizer can improve root development and soil urease, invertase and SOD activities and decrease MDA content, which are factors related to cabbage yield and quality.