外源硅对土壤吸附磷素特征及有效性的影响

发布时间：2018-04-20 03:28

  本文选题：外源硅 + 土壤磷　； 参考：《沈阳农业大学》2017年硕士论文

【摘要】：磷素是植物生长发育所必需的营养元素,在农业生产实践环节中,如何高效率地利用磷素一直备受关注。目前,国内外关于施硅改变土壤磷有效性的研究工作较多,但并未考虑到硅酸盐的碱性和伴随阳离子对反应体系的影响,所以并不能准确判断硅素对土壤磷素活性作用的效果。为此,本试验在消除硅酸钾碱性和钾离子影响的基础上,进行室内模拟试验和生物试验,研究外源硅对土壤及铁氧化物吸附磷特性的影响,探讨施硅条件下土壤磷有效性的变化,结合矿物学与土壤化学的理论,揭示外源硅改变土壤磷的吸附特征及有效性的作用机制,以期为生产中合理地配合施用硅、磷肥料,提高磷肥利用率,减少农业面源污染提供科学依据。得到的主要结果与结论如下:1.在相同的磷吸附平衡浓度条件下,加硅可降低土壤对磷的吸附量。三种方程(Langmuir方程、Freundlich方程和Temkin方程)对土壤吸附磷的等温试验数据拟合结果均达到显著水平。在Langmuir方程中,随着外源硅施入量的增加,吸附平衡常数(K1)、最大吸附量(Xm)和最大缓冲容量(MBC)均逐渐减少,表明外源硅的施入会使土壤对磷的吸附速率变慢、最大吸附量减少,降低土壤对磷的吸附能力。在Freundlich方程中,随着外源硅施入量的增加,吸附容量(K2)、吸附强度(n)均变小,说明外源硅的施入会导致土壤对磷吸附点位的减少,使土壤对磷的吸附强度减弱。2.在相同的磷吸附平衡浓度条件下,外源硅能抑制针铁矿和水铁矿对磷的吸附。在描述铁氧化物对磷的吸附特征时,三种方程(Langmuir方程、Freundlich方程和Temkin方程)都能对其进行较好的拟合,但其中以Langmuir方程拟合的结果最优。在Langmuir方程中,随着外源硅施入量的增加,K1值减小,MBC降低,Xm基本保持不变,表明外源硅的施入会使铁氧化物对磷的吸附速率变慢、吸附能力减弱,但并为改变铁氧化物的最大吸附量。硅的施入可以使铁氧化物表面吸附的磷酸根基团发生红移,趋于更为不稳定状态。外源硅对铁氧化物吸附磷的影响是土壤吸附磷能力减弱的主要原因之一。3.施硅后,土壤中的H_2PO_4~+离子活度增强,土壤磷位势升高,土壤的供磷强度增强。同时,硅使土壤积累态磷的释放量增加,土壤磷饱和度升高,提高了土壤中磷的移动性与活性。盆栽试验结果表明,磷硅配施促进了水稻植株生长,可使株高、生物量有所增加。硅、磷的施用都不同程度提高了两种土壤中水稻植株体内的磷含量。
[Abstract]:Phosphorus is a necessary nutrient element for plant growth and development. How to utilize phosphorus efficiently in agricultural production has been paid more and more attention. At present, there are many researches on the effect of silicon application on the availability of soil phosphorus, but the effect of silicate alkalinity and associated cations on the reaction system is not taken into account, so the effect of silicon on soil phosphorus activity can not be judged accurately. Therefore, on the basis of eliminating the effects of potassium silicate alkalinity and potassium ion, the experiments were carried out in laboratory and biological experiments to study the effects of exogenous silicon on the adsorption characteristics of phosphorus by soil and iron oxides. This paper discusses the change of soil phosphorus availability under the condition of silicon application, combined with the theory of mineralogy and soil chemistry, to reveal the adsorption characteristics of soil phosphorus and the mechanism of the effect of exogenous silicon on the soil phosphorus adsorption, in order to reasonably coordinate the application of silicon and phosphate fertilizer in production. Improving the utilization rate of phosphorus fertilizer and reducing agricultural non-point source pollution provide scientific basis. The main results and conclusions are as follows: 1. Under the condition of the same phosphorus adsorption equilibrium concentration, adding silicon can reduce the amount of phosphorus adsorption in soil. The fitting results of the three equations, Freundlich equation and Temkin equation, were significant. In the Langmuir equation, the adsorption equilibrium constant (K _ (1)), maximum adsorption capacity (X _ (m)) and maximum buffer capacity (Langmuir) decreased with the increase of applied amount of exogenous silicon, which indicated that the application of exogenous silicon could slow down the adsorption rate of phosphorus and decrease the maximum adsorption capacity. The adsorption ability of soil to phosphorus was reduced. In the Freundlich equation, with the increase of the amount of exogenous silicon applied, the adsorption capacity of K _ (2 +) and the adsorption intensity of K _ (2 +) were all decreased, which indicated that the application of exogenous silicon would lead to the decrease of the site of phosphorus adsorption and the decrease of soil's adsorption intensity of phosphorus. Under the condition of the same phosphorus adsorption equilibrium concentration, exogenous silicon can inhibit the phosphorus adsorption of goethite and water ore. In describing the adsorption characteristics of iron oxides to phosphorus, the three kinds of equations, Freundlich equation and Temkin equation, can fit them well, but the Langmuir equation is the best. In the Langmuir equation, with the increase of the amount of exogenous silicon applied, the decrease of K1 value and the decrease of Xm remained unchanged, indicating that the adsorption rate of iron oxide on phosphorus was slower and the adsorption capacity was weakened. However, the maximum adsorption capacity of iron oxides was changed. The addition of silicon can make the phosphate group adsorbed on the surface of iron oxide red shift and tend to be more unstable. The effect of exogenous silicon on the adsorption of phosphorus by iron oxides is one of the main reasons for the decrease of phosphorus adsorption ability of soil. After the application of silicon, the activity of H2PO4 ~ + in soil increased, the potential of phosphorus in soil increased, and the intensity of phosphorus supply in soil increased. At the same time, silicon increased the release of accumulated phosphorus and increased the saturation of phosphorus in the soil, which increased the mobility and activity of phosphorus in the soil. The results of pot experiment showed that the combination of phosphorus and silicon promoted the growth of rice plants and increased the plant height and biomass. The application of silicon and phosphorus increased the content of phosphorus in rice plants.
【学位授予单位】：沈阳农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S153
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本文编号：1776052