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本试验测定了浙江省几种代表性土壤对磷的等温吸持特性。实测值与Frundlich、Langmuir、两项式Langmuir和Temkin方程都很符合,相关系数变化范围在0.919—0.999之间,都达到极显著水平。其中以简单Langmuir等温式与本实验资料最为吻合。从Langmuir方程得到的土壤吸持特性值(k×qm)被认为与土壤供磷特性有关。几种供试样品的(k×qm)值是:针铁矿21100>黄筋泥4218>黄筋泥田991>青紫泥798>粉泥田660>高岭石485>老黄筋泥田423>泥质田298。根据土壤吸持特性值以田菁进行盆栽试验来估算作物磷肥需要量,结果表明,供磷强度0.3ppm P基本能满足田菁早期生长的需要。为使不同土壤达到相同的供磷强度,(k×qm)值大的土壤要求更高的有效磷值。供试土壤的几种磷素指标:E值、Bray1-P值和(NaOH-Na_2C_2O_4)法值对(k×qm)值的变化比较敏感,而EDTA-P和Olsen-P指标对(k×qm)值的变化较为迟钝。
This experiment measured the isothermal adsorption of phosphorus on several representative soils in Zhejiang Province. The measured values are in good agreement with Frundlich, Langmuir, two-equation Langmuir and Temkin equations with correlation coefficients ranging from 0.919 to 0.999, both of which reach extremely significant levels. Among them, the simple Langmuir isotherm is the most consistent with the experimental data. Soil sorption characteristics (k × qm) obtained from the Langmuir equation are considered to be related to soil P availability. The values of (k × qm) for several samples tested were goethite 21100> yellow tendon 4218> yellow tendon 991> purple brucellite 798> muddy field 660> kaolinite 485> yellow tendon muddy field 423> argillaceous Tian 298. According to the characteristics of soil holding capacity, potash experiment was used to estimate the requirement of phosphate fertilizer. The results showed that the phosphorus supply of 0.3ppm P can basically meet the needs of early growth of Jingjing. For different soils to reach the same phosphorus supply, soils with large (k × qm) values require higher available phosphorus. The results showed that the values of E, Bray1-P and (NaOH-Na_2C_2O_4) were sensitive to the changes of (k × qm), while the indexes of EDTA-P and Olsen- qm) value changes more sluggish.