Combined application of biochar and nitrogen fertilizer on nitrogen accumulation and nitrogen use efficiency of winter wheat

Cutting nitrogen fertilizer (NF) input to boost efficiency and recycling wheat straw into biochar are vital technical paths for green and high-yield winter wheat production across the Huang-Huai-Hai Plain. Clarifying the synergistic effects of co-applying biochar and NF bears great practical significance for local wheat cultivation. To investigate the effects of combined application of the two on the growth, grain yield, nitrogen accumulation (NA) and NF utilization efficiency of winter wheat, a split-zone design was carried out using the strong-gluten wheat Jimai 44 as the material at the experimental base in Yuanyang, Henan Province, China. Two main zones, one with no application and the other with 8.0t·ha − 1 biochar, and five NF sub-zones (0, 70, 140, 220, 290 kg·ha − 1 ) were set up. Results showed that the combined application of biochar and NF significantly promoted plant height, stem tiller number, leaf area index and dry matter accumulation in wheat, and delayed post-flowering chlorophyll degradation. Among them, the treatment with 8.0t·ha − 1 biochar NF at 220 kg·ha − 1 had the best overall performance, with plant height of 74.2 cm, dry matter accumulation at maturity of 13,658.9 kg·ha − 1 , which was 15.5% higher than the application of the same amount of NF alone. The number of panicles per hectare was 517.8 × 10 4 ·ha − 1 , which was 13.4% higher than applying the same amount of NF alone. The grain yield reached 11256.8 kg·ha − 1 , an increase of 11.6% compared to applying the same amount of NF alone. Meanwhile, the apparent utilization rate of NF increased by 7.8% points compared to applying an equal amount of NF alone, and the agronomic utilization rate of NF increased by 12.0% compared to applying an equal amount of NF alone. Excessive nitrogen application led to a decrease in growth and utilization efficiency. In summary, biochar had a significant synergistic effect with NF. It was recommended to adopt a fertilization mode of 220 kg·ha − 1 NF combined with 8.0t·ha − 1 biochar. This mode could simultaneously achieve high wheat yield, efficient nitrogen absorption, and efficient NF utilization, while balancing the two major production goals of fertilizer reduction and straw resource utilization.