1.Nanjing University of Information Sciences and Technology;2.College of Applied Meteorology, Nanjing University of Information Science and Technology
Supported by the National Natural Science Foundation of China (No. 42077087)
以江西鹰潭孙家典型红壤小流域中期稻田(MP)、新稻田(NP)与老稻田(OP)的发生层土壤为研究对象，基于吸附-解吸实验与结构方程模型，分析了稻田红壤各发生层土壤磷的固持能力(PSI)、最大固持容量(MCSP)及释放潜能的变化差异与影响因子，明确了固定态磷的释放机制与流失风险。结果表明：随发生层深度的增加，稻田红壤PSI及MCSP逐渐增大，二者变化分别为：MP > NP > OP与NP > MP > OP；但稻田红壤发生层中电性吸附态磷(CaCl2-P)及OP剖面专性吸附态磷(EDTA-P)逐渐降低，而MP剖面和NP剖面的EDTA-P以及稻田红壤发生层的残留态磷(Red-P)则相反；OP剖面发生层CaCl2-P与EDTA-P的比值随发生层深度的增加呈逐渐升高趋势，且显著高于MP和NP剖面。结构方程模型分析结果表明，土壤有机质、全磷、pH和铁铝氧化物之间相互作用且协同调控着稻田红壤的磷吸附位点数量及其吸附-解吸能力。稻田红壤水耕层(Ap层)土壤吸磷能力弱、释磷能力强，土壤磷流失风险大；而氧化还原层(Br)和母质层(C)土壤吸磷能力强、释磷能力弱，土壤磷固持容量大。与新稻田和中期稻田剖面相比，老稻田发生层土壤中吸附态磷更难以向专性吸附态磷及残留态磷转化，土壤磷流失风险相对较大，需及时采取相应的调控措施。
【Objective】This study aimed to analyze the change of phosphorus fixation capacity and release potential in different occurrence layers of red paddy soil, to clarify the release mechanism of fixed phosphorus(P), and to evaluate the loss risk of P in red paddy soil with different planting years.【Method】Soil samples were collected from the bottom to the top of three typical red paddy fields in Yingtan, Jiangxi Province. These paddies included a mid-phase paddy field (MP), a new paddy field (NP) and an old paddy field (OP). Based on the adsorption-desorption experiment and structural equation model, the variation differences and influencing factors of phosphorus retention capacity (PSI), maximum capacity of soil fixed phosphorus (MCSP) and the release potential of the soil were analyzed.【Result】With the increase of pedogenic horizons depth, PSI and MCSP of red paddy soil gradually increased, and the order of their changes were: MP > NP > OP and NP > MP > OP. The desorption capacity of electrostatically adsorbed state P (CaCl2-P) of OP, MP and NP profiles and the desorption capacity of specific adsorbed state P (EDTA-P) in the OP profile gradually decreased with the increasing profile depth. Also, the EDTA-P in MP (except Ap1 layer) and NP profiles and residual P (Red-P) in soil pedogenic horizons followed an opposite trend. With the increase of profile depth, the CaCl2-P/EDTA-P in the pedogenic horizons of the OP profile increased, which was significantly higher than that in the MP and NP profiles. The adsorption-desorption capacity of phosphorus in red paddy soil is mainly affected by SOM (soil organic matter), TP (total phosphorus), pH and iron-aluminum oxides. The interaction between SOM, TP, pH and iron-aluminum oxides jointly regulates the number of phosphorus adsorption sites and the strength of adsorption-desorption capacity in red paddy soil.【Conclusion】In this research, it was found that the Ap layer of red paddy soils was characterized by the weak capacity of the soil P sorption and strong capacity of P desorption and a high risk of soil P loss. Meanwhile, Br and C layers showed a stronger soil P sorption capacity and a weaker P desorption capacity, and a higher soil P fixation capacity than the Ap layer. Compared with the profile of OP, the exogenous P adsorbed in pedogenic horizons of NP and MP was more easily converted to the specialized adsorption state and residual state P, thus, resulting in a reduced risk of soil P loss. The risk of P loss in the OP profile was relatively higher than its counterparts, and timely regulatory measures are needed.
NIU Ben, WANG Yanling. Retention Capacity and Release Potential of Soil Phosphorus in Paddy Red Soil Pedogenic Horizons with Different Planting Years[J]. Acta Pedologica Sinica, DOI:10.11766/trxb202205160257,[In Press]