The North China Plain suffers excessive application of nitrogen (N) and soil degradation. Recently, biochar has been promoted as an agricultural soil amendment to ameliorate soil quality, increase crop yield and mitigate greenhouse gas emissions. However, most proofs on the positive effects of biochar addition have been based on small plots or short-term field studies located in tropical or subtropical regions with defective soils. A long-term field experiment was designed with five N levels and two biochar rates to observe the changes in crop (winter wheat and summer maize) growth and soil chemical quality. Notably, crop yield was strongly dependent upon N application, with both wheat and maize yields increasing with N application. Biochar addition increased crop yield but not significantly, although the increase in grain yield was 0.96 t/ha in a rotation. Correlation analysis revealed that the optimal root-layer soil mineral N (Nmin) for crop production was around N120, especially with biochar addition. The effect of fertilization on soil chemical quality was mainly reflected in the increase in soil organic carbon (SOC), and the highest value was obtained at N60 whether or not biochar was applied. Overall, biochar addition did not appear to promote wheat and maize growth or increase the yield on calcareous alluvial soils in temperate regions, but significantly enhanced SOC content, especially at N60, which may play an important role in sustainable agricultural production.

中文翻译：

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温带地区氮肥和生物炭施肥对作物产量和土壤化学质量的交互作用

华北平原遭受氮（N）过量施用和土壤退化。最近，生物炭已被推广为一种农业土壤改良剂，以改善土壤质量、增加作物产量和减少温室气体排放。然而，大多数关于添加生物炭的积极影响的证据都是基于位于土壤有缺陷的热带或亚热带地区的小块土地或短期实地研究。设计了 5 个氮水平和 2 个生物炭用量的长期田间试验，观察作物（冬小麦和夏玉米）生长和土壤化学质量的变化。值得注意的是，作物产量强烈依赖于施氮量，小麦和玉米的产量都随着施氮量的增加而增加。添加生物炭增加作物产量但不显着，尽管谷物产量增加为 0。96 吨/公顷轮作。相关分析表明，作物生产的最佳根层土壤矿物质 N (Nmin) 约为 N120，尤其是添加生物炭。施肥对土壤化学质量的影响主要体现在土壤有机碳（SOC）的增加上，无论是否施用生物炭，均在N60时获得最高值。总体而言，在温带地区，添加生物炭似乎并没有促进小麦和玉米的生长或增加钙质冲积土壤的产量，但显着提高了 SOC 含量，尤其是在 N60 时，这可能在可持续农业生产中发挥重要作用。施肥对土壤化学质量的影响主要体现在土壤有机碳（SOC）的增加上，无论是否施用生物炭，均在N60时获得最高值。总体而言，在温带地区，添加生物炭似乎并没有促进小麦和玉米的生长或增加钙质冲积土壤的产量，但显着提高了 SOC 含量，尤其是在 N60 时，这可能在可持续农业生产中发挥重要作用。施肥对土壤化学质量的影响主要体现在土壤有机碳（SOC）的增加上，无论是否施用生物炭，均在N60时获得最高值。总体而言，在温带地区，添加生物炭似乎并没有促进小麦和玉米的生长或增加钙质冲积土壤的产量，但显着提高了 SOC 含量，尤其是在 N60 时，这可能在可持续农业生产中发挥重要作用。