Abstract: We examined the changes in soil enzyme activities and cultivable microorganisms, as well as yield and quality of Chinese cabbage with different maturity periods (early maturing and late maturing) under four fertilization treatments with different proportions of chemical fertilizer nitrogen (urea) and organic fertilizer nitrogen (organic manure). The results showed that, for the early-maturing variety ‘Degao 16’, combined application of 1/2 organic manure and inorganic fertilizer (T₂) had higher activities of invertase, urease, and catalase, higher soil organic matter content, and more soil cultivable microorganisms at both the rosette stage and head-tightening stage. The late-maturing variety ‘Qinghua 76’ performed well with T2 treatment at the rosette stage. At the headtightening stage, ‘Qinghua 76’ under combined application of 1/4 organic manure and inorganic fertilizer (T₁) had higher soil enzyme activity, organic matter content and the total amount of soil cultivable bacteria, actinomycetes and cultivable microorganisms than other treatments and CK. Meanwhile, the early-maturing variety ‘Degao 16’ under T₂ treatment had 10.0% more yield than under single chemical fertilizer application. The late-maturing variety ‘Qinghua 76’ under T₂ treatment performed better, with an 8.9% enhancement of yield as compared to the treatment with chemical fertilizer alone. Treatments T₁ and T₂ significantly increased the contents of soluble protein, soluble sugar, and vitamin C in Chinese cabbage, and reduced the contents of crude fiber and nitrate. Therefore, reducing the application of chemical fertilizers but applying bio-organic fertilizers at an appropriate ratio regulated the quantity and community structure of soil microorganisms, increased soil enzyme activity, and promoted plant growth, thereby enhancing Chinese cabbage yield and quality. The early-maturing variety ‘Degao 16’ Chinese cabbage combined with 1/2 bio-organic fertilizer and the late-maturing variety ‘Qinghua 76’ combined with 1/4 bio-organic fertilizer had the best performance.

Key words: Chinese cabbage, maturity period, application proportion, soil property, yield.