Abstract: To investigate the effects of humic acid and biochar addition on soil phosphorus supply and maize phosphorus uptake and utilization in red soil farmland under phosphorus reduction conditions，a randomized complete block design was adopted. Under 40% phosphorus reduction（P₂，P₂O₅ 90 kg/ha），four treatments were set up with different levels of humic acid（H₁，10 000 kg/ha；H₂，5 000 kg/ha）and biochar（B₁，10 000 kg/ha；B₂，5 000 kg/ha），using the local conventional phosphorus application rate（CK，P₂O₅ 150 kg/ha） as the control.The effects of humic acid and biochar addition under phosphorus reduction on the physicochemical properties of red soil，maize phosphorus uptake，and yield were studied.The results showed that，compared with the CK treatment，the addition of humic acid and biochar could，to varying degrees，reduce soil bulk density in the 0—30 cm plough layer，increase soil total porosity and capillary water holding capacity，raise red soil pH and cation exchange capacity（CEC），improve the physicochemical properties of the plough layer soil，increase soil organic matter content，and significantly affect the activities of acid phosphatase（ACP）and alkaline phosphatase（ALP）.Among them，both P₂H₁ and P₂B₁ treatments increased soil total phosphorus and available phosphorus contents. Compared with CK，at the trumpet stage，total phosphorus content in P2H1 and P2B1 treatments increased significantly by 35.35% and 35.40%，respectively，and available phosphorus content increased by 13.92% and 35.69%，respectively；at the dough stage，total phosphorus content in P₂H₁ and P2B1 treatments increased by 6.38% and 48.94%，respectively，with the P₂B₁ treatment showing a significant difference compared with CK.Compared with CK，at the dough stage，root and stem biomass and root‑to‑shoot ratio of P₂H₁ and P₂B₁ treatments increased significantly by 24.61%，3.81%，24.65% and 16.65%，12.39%，9.75%，respectively；maize yield increased by 8.46% and 12.03%，respectively；and leaf phosphorus uptake increased significantly by 22.14% and 37.57%，respectively.Correlation analysis of maize yield and phosphorus uptake with biomass and soil factors revealed that alkaline phosphatase activity and organic matter content were extremely significantly positively correlated with total phosphorus and available phosphorus content；soil total porosity was significantly positively correlated with total phosphorus content and extremely significantly positively correlated with available phosphorus content；CEC and soil capillary water holding rate were significantly positively correlated with available phosphorus content；yield was significantly positively correlated with total phosphorus content and positively correlated with available phosphorus content； phosphorus uptake was positively correlated with total phosphorus content.Comprehensively，humic acid and biochar improve the phosphorus supply capacity of red soil by regulating soil physicochemical properties and phosphatase activities，ultimately promoting efficient phosphorus uptake and utilization by maize. Under 40% phosphorus reduction，the application of 10 000 kg/ha biochar can effectively improve the physicochemical properties of red soil，promote phosphorus supply and maize phosphorus uptake，and ensure maize growth，development and yield formation.

Key words: Maize, Red soil, Humic acid, Biochar, Phosphorus reduction, Phosphorus uptake and utilization

摘要： 为探究红壤耕地在减磷条件下，添加腐植酸和生物炭对土壤磷供给及玉米磷吸收利用的影响，采取随机区组设计，在减磷40%（P₂，P₂O₅ 90 kg/hm²）条件下，分别设置不同水平的腐植酸（H₁，10 000 kg/hm²；H₂，5 000 kg/hm²）和生物炭（B₁，10 000 kg/hm²；B₂，5 000 kg/hm²）共4 个处理，以当地常规施磷量（P₂O₅ 150 kg/hm²）作为对照（CK），研究减磷条件下添加腐植酸和生物炭对红壤理化性质、玉米磷吸收量及产量的影响。结果表明，与CK处理相比，添加腐植酸和生物炭均能不同程度降低0~30 cm耕层土壤容重，增加土壤总孔隙度和毛管持水率，提高红壤pH值和阳离子交换量（CEC），改善耕作层土壤理化性质，提高土壤有机质含量，显著影响酸性磷酸酶（ACP）与碱性磷酸酶（ALP）活性。其中，P₂H₁和P₂B₁处理均可提高土壤全磷和有效磷含量。与CK相比，大喇叭口期P₂H₁和P₂B₁处理的全磷含量分别显著提高35.35%、35.40%，有效磷含量分别提高13.92%、35.69%；蜡熟期P₂H₁和P₂B₁处理的全磷含量分别提高6.38%、48.94%，且P₂B₁处理与CK处理差异显著。与CK相比，蜡熟期P₂H₁和P₂B₁处理的根、茎生物量和根冠比分别显著提高24.61%、3.81%、24.65% 和16.65%、12.39%、9.75%，玉米产量分别提高8.46%、12.03%，叶磷吸收量分别显著提高22.14%、37.57%。玉米产量和磷吸收量与生物量、土壤因子之间的相关性分析结果表明，碱性磷酸酶活性、有机质含量与全磷和有效磷含量均呈极显著正相关，土壤总孔隙度与全磷和有效磷含量分别呈显著正相关和极显著正相关，CEC、土壤毛管持水率与有效磷含量分别呈显著正相关；产量与全磷和有效磷含量分别呈显著正相关和正相关，植株磷吸收量与全磷含量呈正相关。综上，腐植酸和生物炭是通过调控土壤理化性质和磷酸酶的活性提高红壤磷供给能力，最终促进玉米磷肥高效吸收利用。在减磷40%条件下，施用10 000 kg/hm²生物炭能有效改善红壤理化性状，促进磷供给和玉米对磷的吸收，保障玉米生长发育和产量形成。

关键词: 玉米, 红壤, 腐植酸, 生物炭, 减磷, 磷吸收利用