【作者】 刘丽；

【导师】 梁成华；

【作者基本信息】 沈阳农业大学 ， 农业环境与生态， 2009， 博士

【摘要】 设施蔬菜栽培土壤中磷素积累现象非常普遍,磷素的释放情况将直接影响磷肥的利用率及其作物有效性,甚至可能对水体生态环境造成危害。本文以长期定位施肥设施（塑料大棚）蔬菜栽培土壤为研究对象,通过室内培养和化学分析相结合的方式,系统地研究了长期定位施肥对设施蔬菜栽培土壤磷素形态及磷素的释放特征,分析了影响磷素释放的因素,并探讨了可能的影响机制,研究结果如下:1.设施蔬菜栽培土壤中各形态磷素组分在全磷（TP）中所占的比例顺序为:HCl-P > Residual-P > NaOH-P_i/NaHCO₃-P_i> H₂O-P >有机磷（NaOH-P_o/NaHCO₃-P_o）。设施土壤H₂O-P, NaHCO₃-P_i, NaOH-P_i和NaHCO₃-P_o的含量均与速效磷含量极显著正相关,而NaOH-P_o和Residual-P的含量与速效磷含量呈极显著负相关;无机磷对速效磷的重要性比有机磷对速效磷的重要性大,NaHCO₃-P_i、NaOH-P_i和HCl-P是土壤速效磷的主要来源。设施蔬菜栽培土壤对磷素的等温吸附可以用Langmuir方程和Freundlich方程来拟合,Freundlich方程的拟合效果最优。2.设施蔬菜栽培土壤的磷素释放动力学可以用Elovich、双常数和抛物线扩散方程很好地描述,其中Elovich方程是最优方程,其次为双常数方程。有机肥和磷素化肥的施用明显增大了设施蔬菜栽培土壤的释磷量和释磷率,增大了Elovich方程的α、DR_in、DR_f值以及双常数方程的a值,但降低了Elovich方程的β值。3.设施蔬菜栽培土壤的磷素释放量及动力学参数与土壤的有机质含量呈显著正相关,与CEC、全磷和速效磷含量呈极显著正相关,但与pH值、粘粒含量、活性铁铝含量没有明显的相关性。同时,磷素释放量及动力学参数与H₂O-P、NaHCO₃-P_i、NaHCO₃-P_o含量呈极显著正相关,与NaOH-P_i呈显著正相关,而与NaOH-P_o和Residual-P呈极显著负相关,与HCl-P负相关但不明显。4.有机酸对设施蔬菜栽培土壤的磷素具有活化作用,但不同种类的有机酸活化土壤磷素的能力不同,柠檬酸的活化能力强于苹果酸。设施蔬菜栽培土壤磷素的释放量和释放率均与有机酸的浓度有关,随有机酸浓度的升高磷素的释放量和释放率增大。有机酸对设施蔬菜栽培土壤磷素的活化过程可以分为三个不同的区域,第Ⅰ区域活化速率很大、曲线很陡、活化较强烈,第Ⅱ区域活化速率较第一区域有所下降、曲线开始平缓但活化量仍随时间的延长而持续增加,之后还有一个更加慢速的第Ⅲ活化区域。5.在各形态磷素组分中,受有机酸影响最大的是NaOH-P_i,随有机酸浓度的升高NaOH-P_i的释放量增大。在有机酸浓度较高时,设施蔬菜栽培土壤中各形态磷素组分的活化量有如下顺序:NaOH-P_i>HCl-P>NaHCO₃-P_i>H₂O-P。铁、铝结合态磷是有机酸活化设施蔬菜栽培土壤的有效磷源。6.有机酸对铁氧化物磷素的释放具有明显的促进作用,加入有机酸后铁氧化物表面的磷素迅速释放且伴随着铁氧化物的大量溶解,但随着时间的延长释出的磷素会发生再吸附现象。7.不同种类的有机酸（柠檬酸、苹果酸、丙二酸、草酸、琥珀酸和酒石酸）都能够不同程度地促进铁氧化物磷素的释放,并且它们对水铁矿释磷的作用明显强于针铁矿。随着pH值的降低,有机酸对铁氧化物磷素释放的促进作用增强。溶解作用是有机酸促进铁氧化物磷素释放的主要机制。更多还原

【Abstract】 Long-term application of phosphorus with animal manure or fertilizer in amounts exceeding removal with crops lead to buildup of phosphorus in greenhouse soils, and increased risks of phosphorus losses to ground and surface water where it could seriously degrade water quality through the stimulation of eutrophication. The objective of this research was to investigate the effects of long-term fertilization on releasing characteristics and fractions of phosphorus from greenhouse soils, and to find out affecting factors and mechanisms for phosphorus release. The results are summarized as follows:1. The relative amounts of phosphorus fractions in total phosphorus （TP） from long-term fertilized greenhouse soils were in the order of HCl-P > Residual-P > NaOH-P_i/NaHCO₃-P_i> H₂O-P > Organic phosphorus （NaOH-P_o/NaHCO₃-P_o）。H₂O-P, NaHCO₃-P_i, NaOH-P_i and NaHCO₃-P_o showed significantly positive correlations with olsen-P, while NaOH-P_o and Residual-P showed significantly negative correlations with olsen-P. Inorganic phosphorus, especially NaHCO₃-P_i, NaOH-P_i and HCl-P, played more important role in plant-available phosphorus than organic phosphorus. Phosphorus adsorption isotherm was successfully described by Langmuir and Freundlich equations, and Freundlich equation was better than Langmuir equation.2. The equations of Elovich, power function and parabolic diffusion were successfully used to describe the kinetics of phosphorus release from greenhouse soils receiving long-term fertilization, the most appropriate of which was Elovich equation followed by power function equation. The application of manure and fertilizer increased releasing amounts and percentages of phosphorus from greenhouse soils, and increased releasing rate parameters such as "α, DR_in, DR_f "of Elovich equation and "a" of power function equation while it decreased "β" of Elovich equation.3. The organic matter （OM）, cation exchange capacity （CEC）, total phosphorus and olsen-P showed significantly positive relationships with releasing amounts as well as with releasing rate parameters of phosphorus from long-term fertilized greenhouse soils. However, pH value, clay content, available Fe and Al showed insignificantly positive relationships with them. Furthermore, H₂O-P, NaHCO₃-P_i, NaHCO₃-P_o and NaOH-P_i showed significantly positive relationships with releasing amounts as well as with releasing rate parameters of phosphorus from long-term fertilized greenhouse soils, while NaOH-P_o and Residual-P showed significantly negative relationships with them.4. Organic acids promoted phosphorus release from greenhouse soils receiving long-term fertilization, and citric acid induced more amount of phosphorus release than malic acid did. The amounts and percentages of phosphorus released from greenhouse soils were increased with increasing additions of organic acids. In generally, phosphorus release from greenhouse soils receiving long-term fertilization was rapid at first few hours （Ⅰstep） and more slowly （Ⅱstep） until an apprarent equilibrium was approached （Ⅲstep） after organic acids addiction.5. Greatest phosphorus was released from NaOH-P_i among phosphorus fractions, and increased with increasing additions of organic acids. When citric acid and malic acid were at high concentrations (≥0.5 mmol L^-1), the releases of phosphorus fractions was in the order of Fe-oxide- and Al-oxide- associated （NaOH-P_i） > Ca-associated （HCl-P） > plant-available inorganic P （NaHCO₃-P_i） > H₂O-P. Fe-oxide- and Al-oxide- associated inorganic P （NaOH-P_i） played an important role in phosphorus release from greenhouse soils receiving long-term fertilization.6. Organic acids induced phosphorus release and Fe dissolution from different iron oxides, and phosphorus could be readsorbed to iron oxides.7. Six organic acids （citric, malic, malonic, oxalic, succinic, and tartaric） promoted phosphorus mobilization from iron oxides in varying degree, and greater phosphorus were released from ferrihytrite than from goethite. There was a consistent trend across both oxides and all organic ligands that phosphorus release increased with decreasing pH. Dissolution was the most important mechanism for phosphorus release from iron oxides.更多还原