关键词: 玉米, 红壤, 腐植酸, 生物炭, 减磷, 磷吸收利用

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