摘要
【目的】适量砒砂岩能有效改良风沙土的吸水和保水特性,但对于砒砂岩改良风沙土的养分有效性尚不清楚。本文研究了不同用量的砒砂岩改良风沙土对磷吸附特性的影响,以期为评价改良土壤对磷的吸附特性,揭示改良土壤对磷的吸附机理和指导磷肥合理施用提供依据。【方法】本试验设计了砒砂岩和风沙土0∶100(L)、10∶90(LS1)、25∶75(LS2)、50∶50(LS3)、75∶25(LS4)、90∶10(LS5)和100∶0(S)(烘干质量比)7个不同比例的改良模式。研究了在25℃下砒砂岩不同添加量改良风沙土的磷吸附动力学和等温吸附特征,并应用吸附动力学模型和等温吸附模型进行参数拟合,以揭示改良土壤对磷的吸附机理,同时分析了砒砂岩添加比例与改良土壤中磷的最大吸附量的关系。【结果】1)同一初始浓度下,随着吸附时间的延长,改良土壤对磷的吸附量呈增大趋势,24 h后逐渐达到平衡。2)吸附时间一定的情况下,随着磷初始浓度的增大,改良土壤对磷的吸附量逐渐增大,直到接近或达到吸附最大值。3)风沙土对磷的吸附量大于砒砂岩的吸附量,改良土壤中随着砒砂岩添加比例的增加,土壤对磷的吸附量呈减小趋势。4)风沙土、砒砂岩和改良土壤对磷的吸附动力学曲线符合准二级动力学模型。等温吸附曲线以Langmuir模型的拟合效果最优。5)风沙土、砒砂岩和改良土壤对磷的吸附属于均质的单层吸附,由膜扩散和颗粒内扩散共同控制吸附反应速率,吸附机理主要是化学吸附和离子交换。6)改良土壤对磷的最大吸附量随砒砂岩添加比例的增加呈线性减小关系。在生产实践中,可通过测定砒砂岩和风沙土对磷的最大吸附量及风沙土中砒砂岩的添加比例来对改良土壤中磷的最大吸附量进行预测。【结论】砒砂岩可显著减小风沙土对磷的吸附固定,增加施入磷肥的有效性。所以当改良土壤恢复植被以后,磷肥施用初期,砒砂岩添加比例较大的改良土壤中,磷素的肥效较好。但随着植物的生长利用,各改良土壤中吸附磷素的释放效果以及磷肥肥效的持续性有待进一步研究。
[ Objectives ] Appropriate amount of soft rock addition to sandy soil could improve water absorbing and holding capacities, but little information about the nutrient availability was published. The adsorption of phosphorus after added into such soft rock modified sandy soil was studied, aiming to understand phosphorus adsorption characteristics and mechanism of soil improvement effect, and to guide reasonable fertilization of phosphorus. [ Methods] Soft rock was mixed with sandy soil in seven ratios： 0：100 （L）, 10：90 （LS1）, 25：75 （LS2）, 50： 50 （ LS3）, 75 ： 25 （ LS4）, 90 ： 10 （ LS5 ） and 100 ： 0 （S）. The adsorption kinetic process and adsorption isotherms of phosphorus were measured at 25℃, the adsorption kinetics and isothermal adsorption model was used to reveal phosphorus adsorption mechanism of improved soils. The relation between proportion of soft rock and maximum amount of phosphorus adsorption in improved soil has been known. [ Results ] 1 ） Under the same initial concentration, the phosphorus adsorption capacity of improved soil showed a trend of increase with the extension of reaction times and gradually achieved balance after 24 h. 2 ）In the case of adsorption time was determined, the phosphorus adsorption quantity nereased gradually with initial concentration increased in improved soil and until to close or reach the maximum amount of phosphorus adsorption. 3） Adsorption capacity of phosphorus was larger in sandy soil than in soft rock. With the increase of the soft rock proportion, phosphorus adsorption of improved soil decreased. 4）The pseudo-second order kinetic modell was the best mode to fit phosphorus absorptive dynamics processes. Within the concentration range in this study, the phosphorus adsorption isotherms were well represented by Langmuir isotherm model. 5 ）The studies on the kinetics and isothermal absorption showed that the phosphorus adsorption of improved soil was homogeneous monolayer adsorption, and both membrane diffusion and intra-particle diffusion were the rate-controlling process in the adsorption system tested. The adsorption mechanism was mainly maximum adsorption of phosphorus in modified soil through measure the maximum adsorption of phosphorus in soft rock and sandy soil and the proportion of soft rock. [ Conclusions ] Soft rock can significantly reduce the phosphorus adsorption of sandy soil and increase the effectiveness of phosphorus fertilizer. So when re-vegetation, the more soft rock proportion in sandy soil, the better effect of fertilizer. However, as plants growth, further understanding of desorption and continuity of phosphorus in improved soil is needed.
出处
《植物营养与肥料学报》
CAS
CSCD
北大核心
2015年第5期1373-1380,共8页
Journal of Plant Nutrition and Fertilizers
基金
中国科学院西部行动计划(KZCX2-XB3-13-02)
教育部新世纪优秀人才支持计划(NCET-13-0487)资助
关键词
磷素
吸附动力学
等温吸附
砒砂岩
风沙土
改良土壤
phosphorus
adsorption kinetics
isothermal adsorption
soft rock
sandy soil
improved soil
