Chitosan microspheres-based controlled-release nitrogen fertilizers improve the biological characteristics of Brassica rapa ssp. pekinensis and the soil

Present study investigates the impact of chitosan microspheres-based controlled-release nitrogen fertilizer (Cm-CRNFs) on biological characteristics of Brassica rapa ssp. pekinensis (Chinese cabbage) and soil. The study was carried out under various four treatments, urea (0.8033 g), blank chitosan microspheres (without urea), Cm-CRNFs (0.8033 g), and a control group (CK). The results indicated that Cm-CRNFs significantly prolonged the nitrogen release and enhanced the plant shoot length, shoot diameter, number of branches, pods, total amino acids, and vitamin C of Brassica rapa ssp. pekinensis as well as increased the soil nutrient availability. Chao index of bacterial diversity analysis showed a significant reduction of 15.89 % in Cm-CRNFs, but the Shannon index value in Cm-CRNFs was increased by 23.55 % compared to CK. Furthermore, Cm-CRNFs treatment significantly influenced genus richness level of Arthrobacter, Archangium, Bacillus, and Flavihumibacter. Moreover, relative abundance of bacteria significantly enhanced Cm-CRNFs, including Acidobacteriota, Acitinobacteriota, Cloroflexi, Cyanobacteria, and Patescibacteria. Soil enzyme activity such as: urease, acid phosphatase, and catalase enzymes in Cm-CRNFs and urea treatment significantly increased. Besides, other enzymes such as: cellulase and β-glucosidase activity decreased in the Cm-CRNFs treatment. It was concluded that Cm-CRNFs potentially prolonged discharge of micro/macronutrients and improved soil bacterial diversity, which ultimately enhanced the soil fertility and improved the soil enzyme activity.