<UnorderedList Mark="Bullet"> <ItemContent> Individual addition of fertilizer N and biochar at 6 t ha−1 increased soil autotrophic and heterotrophic respiration, respectively. </ItemContent> <ItemContent> Biochar counteracted the promotional effect of N fertilizer on soil autotrophic respiration. </ItemContent> <ItemContent> N fertilization accelerated heterotrophic respiration in soils amended with biochar. </ItemContent> <ItemContent> Combined fertilizer N and biochar raised r/K microbial strategy ratio by supplying nutrients. </ItemContent> <ItemContent> Combined addition of fertilizer N and biochar at 3 t ha−1 more effectively enhanced soil organic carbon accumulation. </ItemContent> </UnorderedList>Biochar and nitrogen (N) fertilizer are widely used to improve crop growth and rebuild soil organic carbon (SOC). However, N fertilizer and biochar addition affect SOC unpredictably because of varying effects on soil autotrophic (Ra) and heterotrophic respiration (Rh). To clarify the influence, a field experiment was conducted in which biochar was input alone at rates of 0, 3, 6, and 12 t ha−1 (BC0, BC3, BC6, and BC12) and in combination with urea at 200 kg N ha−1 (BC0U, BC3U, BC6U, and BC12U). Biochar alone had a negligible effect upon Ra regardless of its rate, whereas individual N fertilization promoted Ra by 62.6% than BC0. Conversely, combined N and biochar decreased Ra by 25.9%–48.2% relative to BC0U, suggesting that biochar and N antagonistically affect Ra. In contrast to Ra, Rh was unresponsive to N alone but showed a significant elevation under biochar at rates of 6 and 12 t ha−1. N fertilization, however, stimulated Rh by 12.1%–17.7% in biocharamended soils, suggesting that biochar and N addition synergistically affect Rh. Microbial community analyses indicated that the increased Rh under the incorporation of biochar and N fertilizer might be attributed to the stimulation of copiotrophic microbes. The lowest Rh/SOC ratio was found in BC3U, suggesting a relatively low decomposition rate of SOC. This study highlights that Rs components exhibit distinct responses to individual N fertilization, biochar amendment and their interaction, and suggests that incorporating biochar at the rate of 3 t ha−1 in N-fertilized soil may potentially enhance soil carbon sequestration.

Contrasting effects of biochar and N fertilization on soil heterotrophic and autotrophic respiration in a maize cropland

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发表日期：

2026年1月19日

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Yuhui Niu,
Zengming Chen,
Deyan Liu,
Weixin Ding

摘要

Individual addition of fertilizer N and biochar at 6 t ha⁻¹ increased soil autotrophic and heterotrophic respiration, respectively.

Biochar counteracted the promotional effect of N fertilizer on soil autotrophic respiration.

N fertilization accelerated heterotrophic respiration in soils amended with biochar.

Combined fertilizer N and biochar raised r/K microbial strategy ratio by supplying nutrients.

Combined addition of fertilizer N and biochar at 3 t ha⁻¹ more effectively enhanced soil organic carbon accumulation.

Biochar and nitrogen (N) fertilizer are widely used to improve crop growth and rebuild soil organic carbon (SOC). However, N fertilizer and biochar addition affect SOC unpredictably because of varying effects on soil autotrophic (Ra) and heterotrophic respiration (Rh). To clarify the influence, a field experiment was conducted in which biochar was input alone at rates of 0, 3, 6, and 12 t ha⁻¹ (BC0, BC3, BC6, and BC12) and in combination with urea at 200 kg N ha⁻¹ (BC0U, BC3U, BC6U, and BC12U). Biochar alone had a negligible effect upon Ra regardless of its rate, whereas individual N fertilization promoted Ra by 62.6% than BC0. Conversely, combined N and biochar decreased Ra by 25.9%–48.2% relative to BC0U, suggesting that biochar and N antagonistically affect Ra. In contrast to Ra, Rh was unresponsive to N alone but showed a significant elevation under biochar at rates of 6 and 12 t ha⁻¹. N fertilization, however, stimulated Rh by 12.1%–17.7% in biocharamended soils, suggesting that biochar and N addition synergistically affect Rh. Microbial community analyses indicated that the increased Rh under the incorporation of biochar and N fertilizer might be attributed to the stimulation of copiotrophic microbes. The lowest Rh/SOC ratio was found in BC3U, suggesting a relatively low decomposition rate of SOC. This study highlights that Rs components exhibit distinct responses to individual N fertilization, biochar amendment and their interaction, and suggests that incorporating biochar at the rate of 3 t ha⁻¹ in N-fertilized soil may potentially enhance soil carbon sequestration.