Effects of cabbage ridge planting and film mulching on soil physical and chemical properties and microbial community in southern Ningxia mountainous areas

Sustainable cabbage cultivation has been significantly confined to the suboptimal agronomic practices, particularly in the cold-climate vegetable production region of Xiji County, on the western foothills of Ningxia's Liupan Mountains, China. In this study, a systematic investigation was made to explore the effects of the different planting patterns on the soil physicochemical properties, enzyme activities, rhizosphere microbial diversity, and cabbage yield. Sustainable challenges were also proposed from the suboptimal practices. A field test was conducted at the Malian Township experimental base in Xiji County. The cabbage cultivar of 'Zhonggan 15' was taken as the material. A two-factor randomized block was also designed as follows. Factor 1 (planting pattern) included the ridged single-row and double-row configurations. While Factor 2 (mulch type) comprised six treatments: no mulch, white plastic, black plastic, silver-black double-colored, black fully biodegradable, and liquid film. The 12 treatments were obtained: ridged single-row no mulch (CK), ridged single-row white film (M1), ridged single-row black film (M2), ridged single-row silver-black double-colored film (M3), ridged single-row black biodegradable film (M4), ridged single-row liquid film (M5); double-row no mulch (SCK), double-row white film (SM1), double-row black film (SM2), double-row silver-black double-colored film (SM3), double-row black biodegradable film (SM4), and double-row liquid film (SM5). Each treatment was replicated three times over two consecutive growing seasons at the same field location. The spring-summer crop was transplanted on May 21, 2024, and then harvested on July 6, 2024. While the summer-autumn crop was transplanted on August 11, 2024, and harvested on October 9, 2024. Finally, an evaluation was performed on the seasonal effects on the root growth, soil moisture, physicochemical properties, enzyme activities, microbial diversity, and yield. Results demonstrated that there were significant seasonal variations. In the spring-summer seedling stage, SM3 treatment shared the superior performance, where the average root diameter increased by 31.6%, compared with the CK. In the summer-autumn seedling stage, SM1 treatments significantly increased the total root volume, thus surpassing CK by 162.8%. Soil moisture retention was varied under different treatments and growth stages. In the spring-summer crop, the M3 treatment elevated the soil moisture content by 37.4% during the seedling stage and 29.3% at the rosette stage, compared with the CK. The M1 and SM3 treatments improved the soil moisture by 35.9% and 24.1%, respectively, during the summer-autumn rosette stage. The soil properties shared the treatment-specific effects. In spring-summer, the SM4 boosted electrical conductivity (EC) by 56.3% and organic matter content by 7.6%. Summer-autumn data showed that the SM5 enhanced the organic matter by 8.7%, compared with the CK. Enzymatic activities exhibited distinct responses. Spring-summer SM3 significantly increased the phosphatase activity by 39.0% and the urease activity by 86.0%. In summer-autumn, the SM4 showed enhanced phosphatase activity by 28.5%, while the SM3 showed elevated urease activity by 21.7%, compared with the CK. There were different microbial community diversities in the cabbage rhizosphere, according to the planting patterns and mulch types. Double-row configurations with the white film (SM1) or black biodegradable film (SM4) substantially increased both bacterial and fungal biomass. In spring-summer, the SM3 and SM4 demonstrated that the optimal performance was achieved to increase the yields by 47.5% and 22.2%, respectively. The summer-autumn yields were generally lower. In conclusion, the superior agronomic strategies were observed in the double-row planting with silver-black double-colored film (SM3) and double-row planting with black biodegradable film (SM4). These treatments significantly enhanced the soil physicochemical properties, microbial abundance, and cabbage yield. Crucially, the spring-summer crop yields were consistently higher than those of the summer-autumn ones. These findings can provide a robust scientific reference to implement the efficient double-row planting with the specific film mulches. A highly effective cultivation can be expected for the cabbage production in the southern mountainous regions of Ningxia, China.