Effects of High-Carbon-Based Fertilizer on Rhizosphere Soil Nitrogen Utilization in Tobacco-Rice Rotation System

China’s low nitrogen fertilizer use raises agricultural prices and environmental dangers. High-carbon fertilizer with biochar could help sequester carbon. High-carbon fertilizer was tested on roasted tobacco cultivation in Chenzhou. No-nitrogen fertilizer treatment assessed nitrogen consumption and economic benefits. Fertilizer-only and cake fertilizer treatments, substituting 13% and 26% of nitrogen with high carbon-based fertilizer, yielded the following results: Replacing 13% of N fertilizer with high-carbon fertilizer increased dry matter accumulation, utilization, agronomic efficiency, application efficiency, and production and investment ratios to 493.97 g-plant-1, 32.39%, 137.43 kg-kg-1, 65168.31 yuan-hm-2, and 8.97 yuan-yuan-1. 484.46 g-plant-1, 34.46%, 148.37 kg-kg-1, 72408.74 yuan-hm-2, and 8.04 yuan-yuan-1 at 26% replacement. High-carbon fertilizer boosted tobacco N fertilizer consumption and economic efficiency more than cake fertilizer. The 26% ratio of chemical fertilizer to organic fertilizer improved tobacco plant growth by improving nitrogen utilization. Using only chemical fertilizer nitrogen, roasted tobacco’s nitrogen distribution was 26%, 27%, 23%, and 24% in roots, stems, leaves, and flowers. Partial replacement with cake or high-carbon fertilizer boosted nitrogen distribution in roasted tobacco stems from 25% to 30%, slightly reducing in roots and leaves. The Chenzhou tobacco-rice rotation system optimizes nitrogen consumption and economic efficiency in roasted tobacco cultivation with high-carbon fertilizer. It outperforms cake fertilizer. A 26% ratio of organic nitrogen to chemical fertilizer outperforms a 13% ratio.