生物炭与磷肥添加对红壤团聚体及其磷组分分布的影响

Effects of Biochar and Phosphorus Application on Red Soil Aggregates and Their Phosphorus Components Distribution

【目的】通过大豆盆栽试验,研究了秸秆生物炭与磷肥添加对红壤团聚体稳定性、磷组分分布与植物磷吸收的影响。【方法】试验包括6个处理:P0(不施磷和生物炭)、P30(30 kg P hm^(−2),不施生物炭)、P90(90 kg P hm^(−2),不施生物炭)、BP0(不施磷,单施4%生物炭)、BP30(30 kg P hm^(−2),施4%生物炭)和BP90(90 kg P hm^(−2),施4%生物炭)。采用湿筛法分离得到粗大团聚体(>2 mm)、细大团聚体(0.25~2 mm)和微团聚体(<0.25 mm)并用连续浸提分级测定了不同团聚体中磷组分分布特征。【结果】①与P0和P30相比,BP0和BP30处理显著促进粗大团聚体形成与稳定,同时促进大豆生长与磷吸收,且BP30处理增幅最大。②与不施生物炭相比,不同磷水平下添加生物炭均显著降低粗大团聚体全磷、总有机磷、NH4F-Po和NaOH-I-Po含量,同时增加细大团聚体HCl-P_(i)和NaOH-II-P_(i)含量与微团聚体总无机磷、HCl-P_(i)和NaOH-II-P_(i)含量。③植株磷吸收与粗大团聚体总有机磷、NaOH-I-Po和NaOH-II-Po显著负相关,但与微团聚体和细大团聚体NH4Cl-P_(i)、HCl-P_(i)和NaOH-II-P_(i)显著正相关。【结论】生物炭与低量磷肥配施可有效改善红壤团聚体结构与稳定性,同时促进大团聚体有机磷的活化与微团聚体无机磷的固持,保障作物磷素供应。

[Objective]The effects of straw biochar and phosphorus(P)fertilizer application were investigated on the distribution of P fractions in red soil aggregates and plant P uptake through soybean pot experiment.[Method]The experiment was set up with the following 6 treatments:P0(no P and biochar),P30(30 kg P ha^(−1),no biochar),P90(90 kg P ha^(−1),no biochar),BP0(no P,4%biochar alone),BP30(30 kg P ha^(−1),combined with 4%biochar)and BP90(90 kg P ha^(−1)combined with 4%biochar).Large macro-aggregates(>2 mm),small macro-aggregates(0.25-2 mm)and micro-aggregates(<0.25 mm)were separated by wet sieve method,and P fractions in different aggregates were determined by sequential fractionation.[Result]①Compared with P0 or P30,BP0 and BP30 significantly promoted the formation and stability of large macro-aggregates,promoted soybean growth and P uptake simultaneously,with the largest increase observed in BP30.②Biochar application at different P levels significantly reduced total P,total organic P,NH4F-Po and NaOH-I-Po content in macro-aggregate,while increased HCl-P_(i)and NaOH-II-P_(i)in small macro-aggregates and total inorganic P,HCl-P_(i)and NaOH-II-P_(i)content in micro-aggregate.(3)The plant P uptake was significantly negatively correlated with the total organic P,NaOH-I-Po and NaOH-II-Po in large macro-aggregates,but significantly positively correlated with NH4Cl-P_(i),HCl-P_(i)and NaOH-II-P_(i)in micro-aggregates and small macroaggregates.[Conclusion]The combined application of biochar and low-level P fertilizer could improve the structure and stability of red soil aggregates effectively,promote the activation of macro-aggregates of organic P and the retention of micro-aggregates of inorganic P to ensure the supply of crop P.The result provides a theoretical basis for the use of biochar in organic P mobilization and crop P uptake.