Biochar-Based Fertilizer Improved Crop Yields and N Utilization Efficiency in a Maize–Chinese Cabbage Rotation System

Optimizing fertilization strategies is crucial for obtaining high crop yields and efficient N utilization. This study aimed to understand the potential increase in crop yield and the N utilization efficiency under biochar-based fertilizer (BF) in a maize–Chinese cabbage rotation system. Biochar-based slow-release fertilizer (BF) is an important nutrient-efficient management strategy. The yields and growth-related traits of the crops, N utilization efficiency, quality, and dynamic changes in soil inorganic N in a maize-cabbage rotation system were investigated in a pot experiment under three N fertilizer application strategies in 2019–2020; the maize stage included (1) zero-N fertilizer, i.e., control (N 0 g pot⁻¹); (2) NPK (N 5.25 g pot⁻¹); and (3) BF (N 5.25 g pot⁻¹). The Chinese cabbage stage included (1) zero-N fertilizer, i.e., control (N 0 g pot⁻¹); (2) NPK (N 6.25 g pot⁻¹); and (3) BF (N 6.25 g pot⁻¹). Compared with the CK and NPK treatments, the BF treatment had the highest average maize and Chinese cabbage yields at 86.99 g plant⁻¹ and 498.88 g plant⁻¹, respectively. BF improved the plant height, stem diameter, and ear height of maize and the leaf length, leaf width, and leaf number of Chinese cabbage, as well as increased the N utilization efficiency of maize and cabbage. BF increased the starch content of maize grain and the amino acid, sugar, and vitamin C contents of cabbage. In the critical growth stages of maize and Chinese cabbage, BF application increased the content of soil inorganic N, which coincided with the nutrient requirements in the critical growth stages of the crops. Overall, BF is an effective method to improve crop yield and N utilization in the maize–Chinese cabbage rotation systems and is a fertilization strategy with broad applicability prospects.