Abstract:

[Objective] Iron is an essential micronutrient for crops, and iron oxides play critical roles in the formation and physicochemical properties of soil aggregates. However, whether the combined field application of biochar and Fe-based amendments produces synergistic effects on the improvement of acidified soils in peanut fields remains unclear and requires further verification through field trials. [Methods] A two-year field experiment was conducted in an acidified peanut-cropping system, in which biochar was co-applied with either zero-valent iron (BC+Fe⁰) or magnetite (BC+Fe₃O₄). Soil physicochemical properties, microbial community structure, and peanut yield were determined to evaluate the soil amelioration potential of these combined amendments. [Results] The combined treatments significantly increased soil pH from 5.48-5.83 to 5.93-6.37 and total organic carbon content from 8.47-9.11 to 11.35-13.55 g·kg⁻¹. They also promoted the formation of macroaggregates (>0.25 mm) and reduced soil bulk density. The application of Fe-based materials alone increased the contents of free iron oxides, organically complexed iron, and Fe²⁺ by 4.56%-35.09%. Following the combined application of biochar and Fe-based materials, the contents of free and amorphous iron oxides and Fe²⁺ increased further. The Shannon and Chao1 diversity indices also increased, while the relative abundances of the three dominant bacterial phyla increased by 0.75%-1.59%. Among the treatments, BC+Fe₃O₄ resulted in the highest pod yield and 100-pod weight, both of which were strongly associated with improved soil properties and increased plant-available Fe. [Conclusion] The combined application of biochar and Fe-based amendments is an effective strategy for ameliorating acidified soils in peanut fields, improving soil quality, increasing microbial diversity, and enhancing peanut productivity. This study provides a new management strategy and a mechanistic basis for the field-scale application of biochar-Fe systems in agricultural soil amelioration.

Key words: straw biochar, Fe-based amendments, zero-valent iron, magnetite (Fe₃O₄), peanut yield, soil improvement

摘要：

【目的】铁是作物必需的微量元素，铁的氧化物影响土壤团聚体的形成和理化性质，本研究旨在通过田间试验验证生物炭和铁基材料的田间联合施用能否发挥对酸化花生田土壤的协同改良效应。【方法】在酸化花生田开展生物炭与铁基材料联合施用（BC+Fe⁰；BC+Fe₃O₄）田间试验，分析了联合施用对土壤理化性质、微生物群落特征以及花生产量的影响，探究联合施用对土壤改良的潜力。【结果】研究发现，联合施用显著提高了土壤pH值（从初始的5.48－5.83增至5.93－6.37）、TOC含量（从8.47－9.11 g·kg⁻¹提升至11.35－13.55 g·kg⁻¹），同时大粒径（>0.25 mm）团聚体比例增加，土壤容重降低。铁基材料单独施用增加了土壤中游离态、络合态氧化铁与二价铁离子的含量（4.56%－35.09%）。联合施用后土壤中游离态、无定型氧化铁和二价铁离子的含量增加；土壤Shannon和Chao1指数较对照组提高，3种优势菌门增加0.75%－1.59%。BC和Fe₃O₄联合施用组的单位产量、百果质量最大，这与土壤性质的改变、可利用性铁等营养物质的增加有关。【结论】生物炭与铁基材料的联合施用是一种有效的土壤改良策略，它能够提高土壤质量，增加微生物多样性，并增强花生的生长表现。该研究为花生田土壤改良提供了新的策略和科学依据，并有助于指导生物炭与铁基材料联合施用在农田土壤改良中的实际应用。

关键词: 秸秆生物炭, 铁基材料, 零价铁, 四氧化三铁, 花生产量, 土壤改良